October 2021 News and research items
Research_News_20_10_2021
Further links and discussion can be found at the groups/links below
Astronomy in New Zealand - Facebook
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https://groups.google.com/g/nzastrochat
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Blogger Posts
http://laintal.blogspot.com/
Reddit
https://www.reddit.com/user/Edwin_Rod_NZ
Quaroa
https://www.quora.com/q/astronomyinnewzealand
Twitter
https://twitter.com/EdwinRodham
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Research papers
The Tidal-Thermal Evolution of the Pluto-Charon System
https://arxiv.org/abs/2109.13206
The Dark Side of Pluto
https://arxiv.org/abs/2110.11976
Characterizing the All-Sky Brightness of Satellite Mega-Constellations
https://arxiv.org/abs/2110.10578
A model Earthsized planet in the habitable zone of a Centauri AB
https://arxiv.org/abs/2110.12565
Characterizing the protolunar disk of the accreting companion GQ Lupi B
https://arxiv.org/abs/2110.04307
The First Interstellar Astronauts Will Not Be Human
https://arxiv.org/abs/2110.13080
The Fine-Tuning of the Universe for Life
https://arxiv.org/abs/2110.07783
Origin of Chirality in the Molecules of Life
https://arxiv.org/abs/2110.12232
The large obliquity of Saturn explained by the fast migration of Titan
https://arxiv.org/abs/2110.04104
Evidence for multiple Ferrel-like cells on Jupiter
https://arxiv.org/abs/2110.07255
Thousands of Qatari genomes inform human migration history and improve imputation of Arab haplotypes
https://www.nature.com/articles/s41467-021-25287-y
A compositional link between rocky exoplanets and their host stars
https://www.science.org/doi/10.1126/science.abg8794
Climate uncertainties caused by unknown land distribution on habitable M-Earths
https://arxiv.org/abs/2110.04310
Mass Transport in a Moist Planetary Climate Model
https://arxiv.org/abs/2110.03719
Carbon cycling and habitability of massive Earth-like exoplanets
https://arxiv.org/abs/2110.03295
The Search for Deliberate Interstellar SETI Signals May Be Futile
https://arxiv.org/abs/2110.11502
Missions to and Sample Returns from Nearby Interstellar Objects
https://arxiv.org/abs/2008.07647
Unveiling shrouded oceans on temperate sub-Neptunes
https://arxiv.org/abs/2108.04745
Reconciling evidence of oxidative weathering and atmospheric anoxia on Archean Earth
https://www.science.org/doi/10.1126/sciadv.abj0108
measuring the occurrence rate and origin of small iron meteoroids at Earth
https://arxiv.org/abs/2109.10265
The Population of Interstellar Objects Detectable with the LSST
https://arxiv.org/abs/2109.10406
Transneptunian Space
https://www.annualreviews.org/doi/10.1146/annurev-astro-120920-010005
WASP-127b
https://arxiv.org/abs/2010.15143
Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths
https://arxiv.org/abs/2103.12760
The 2021 outburst of RS Oph
https://arxiv.org/abs/2109.01101
Formation of polar terrestrial circumbinary planets
https://arxiv.org/abs/2109.11653
Reflected spectroscopy of small exoplanets
https://arxiv.org/abs/2109.11659
A comprehensive revisit of Galileo NIMS observations of Europa
https://arxiv.org/abs/2109.11650
A Benchmark System of Small Planets for Future Atmospheric Characterization
https://iopscience.iop.org/article/10.3847/1538-3881/ac1171
4 very interesting papers on the Trappist 1 system here
The dynamics of the TRAPPIST-1 system
https://arxiv.org/abs/2109.10984
The TRAPPIST-1 Habitable Atmosphere Intercomparison 1
https://arxiv.org/abs/2109.11457
The TRAPPIST-1 Habitable Atmosphere Intercomparison 2
https://arxiv.org/abs/2109.11459
The TRAPPIST-1 Habitable Atmosphere Intercomparison 3
https://arxiv.org/abs/2109.11460
Why do M dwarfs have more transiting planets
https://arxiv.org/abs/2110.02971
No Transits of Proxima Centauri Planets inHigh-Cadence TESS Data
https://arxiv.org/abs/2110.10702
Laser Communication with Proxima and Alpha Centauri using the Solar Gravitational Lens
https://arxiv.org/abs/2110.10247
Interstellar space biology via Project Starlight
https://reader.elsevier.com/reader/sd/pii/S0094576521005518
Defining the “Ice Shed” of the Arctic Ocean's Last Ice Area and Its Future Evolution
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021EF001988
A Unified Model for the Fan Region and the North Polar Spur
https://arxiv.org/abs/2109.14720
First Observations of a Transient Polynya in the Last Ice Area North of Ellesmere Island
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL095099
‘Phased transition’ to phase transition: The network consequences of reconnecting
https://www.tepunahamatatini.ac.nz/2021/10/22/phased-transition-to-phase-transition/
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Interesting News items
Auckland night sky
https://www.nzherald.co.nz/nz/aucklands-bright-lights-harming-ecosystems-spoiling-galaxy-view/X23PRCDSZCM2SQPC66A5UR3RXA
Bright skies named colour of the year – here’s why there’s so much more to the heavens than blue
https://sciblogs.co.nz/guestwork/2021/09/28/bright-skies-named-colour-of-the-year-heres-why-theres-so-much-more-to-the-heavens-than-blue/
Interesting look at the inner solar system
https://www.centauri-dreams.org/2021/09/28/hit-and-run-earth-venus-and-planet-shaping-impacts/
SwRI Scientists Confirm Decrease In Pluto's Atmospheric Density
http://spaceref.com/pluto/swri-scientists-confirm-decrease-in-plutos-atmospheric-density.html
Careful study of data from the New Horizons mission indicates that an iconic, caldera-looking feature isn’t what it seems.
https://skyandtelescope.org/astronomy-news/plutonian-mounts-arent-ice-volcanoes
Journey to the Surface of Venus
https://www.airspacemag.com/airspacemag/journey-surface-venus-180978688
Earth tipping?
http://astrobiology.com/2021/10/did-the-earth-tip-on-its-side-84-million-years-ago.html
An interesting look at the physics of the shape of the Earth plus some visulation software I need to try out too
https://astronomy.com/news/2021/10/earths-equatorial-bulge-shapes-the-planets-physics
The United Nations’ Office of Outer Space Affairs is considering issues of light pollution spanning from streetlights to satellites.
https://skyandtelescope.org/astronomy-news/taking-dark-skies-to-the-united-nations/
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Updates from Andrew B,
Mars.
Imaged: Saturday 25th September 2021. Sol 213.
New images, with the Navigation Camera.
Navigation Camera shows views in the mid martian afternoon in Jezero Crater. Citadelle rock formations and dunes in South Seitah.
Image looking back with the MMRTG visible.
MMRTG / Multi Mission Radioisotopic Thermoelectric Generator (uses heat from the natural radioactive decay of Plutonium 238 to generate electrical power, not undergoing nuclear reactions) on board Mars Perseverance Rover. The half life of Plutonium 238 is 87.7 years, is element # 94 & atomic weight 238.04.
Plutonium 238 has 94 Protons, 144 Neutrons, 94 Electrons and slowly decays to become Uranium 234 on it's way to eventually becoming Lead.
On Wednesday 29th September 2021, the final set of instructions will be sent to Mars Perseverance Rover to allow for continued data acquisition and on board storage of said data whilst Mars undergoes Solar Conjunction on Thursday 7th October 2021. Mars then to all intents passes behind the Sun as viewed from Earth. Communication with all Mars spacecraft will not be possible for about two weeks. Mars Perseverance Rover will return recorded data shortly after coming out of Solar Conjunction in mid October.
Images taken between 15:12 & 15:34 LMST. Local Mars Standard Time at Jezero Crater.
Jezero Crater, Syrtis Major Quadrangle.
MastCam Z (Zoom) Camera & Navigation Camera.
Text: Andrew R Brown.
NASA / JPL-Caltech / ASU / MSSS / LANL / CNES / IRAP. Mars Perseverance Rover.
Mercury.
Friday 1st October 2021, the BepiColombo spacecraft passed Mercry at a distance of 199 KM / 123 miles, the engineering cameras and many of the scientific instruments were used to gather new images and data on The First Rock from the Sun.
The encounter is using the gravity of Mercury to slowly alter the trajectory and reduce the Heliocentric / Sun centred orbital speed towards Mercury, eventually with Hermcentric / Mercury centred orbital insertion on: Friday 5th December 2025.
This was the first of five Mercury encounters on: Saturday 2nd October 2021, BepiColombo passed @ a distance of only 199 KM / 123 miles..
Jere north is to the lower right, with the Rudaki lava plains well seen alongside Calvino Crater and the 166 KM / 103 mile wide Lermontov Crater. wjich appears brighter due to the low temperature volatile hollows on it's floor.
Mercury orbits the Sun once every 87 days, 23 hours and 18 minutes. The orbit around the Sun is quite elliptical and distance from the Sun varies from Perihelion, closest to the Sun @ 46,001,200 KM, mean distance of 57,909,050 KM and Aphelion, furthest from the Sun @ 69,816,900 KM.
Mercury rotates on its axis once every 58 days, 15 hours and 30 minutes. In relation to the Sun though takes 175 days, 22 hours and 36 minutes. Mercury rotates three times for every two orbits around the Sun.
Mercury has a diameter of 4,880 KM / 3,032 miles & a mass of 328.5 billion trillion tons (328.5 followed by twenty zeros).
The surface temperature at the equator varies from minus 186 Celsius at sunrise to 427 Celsius just after hermian noon.
Our own Earth with a diameter of 12,742 KM / 7,917 miles, with a mass of 5,972.2 billion trillion tons (5,972.2 followed by twenty zeros) and a mean density of 5.517 G/CM3.
The following Mercury braking enounters will occur on:
Thursday 23rd June 2022.
Tuesday 20th June 2023.
Thursday 5th September 2024.
Monday 2nd December 2024.
Thursday 9th January 2025.
Hermcentric orbital insertion: Friday 5th December 2025.
End of Primary Mission: Saturday 1st May 2027.
End of possible extended mission: Monday 1st May 2028.
Text: Andrew R Brown.
ESA / JAXA Bepi-Colombo spacecraft.
Text: Andrew R Brown.
ESA / JAXA Bepi-Colombo spacecraft.
Mercury.
Friday 1st October 2021, the BepiColombo spacecraft passed Mercry at a distance of 199 KM / 123 miles, the engineering cameras and many of the scientific instruments were used to gather new images and data on The First Rock from the Sun. Fantastic images, very high quality.
BepiColombo was 2,418 KM / 1,502 miles from Mercury in this image.
The encounter is using the gravity of Mercury to slowly alter the trajectory and reduce the Heliocentric / Sun centred orbital speed towards Mercury, eventually with Hermcentric / Mercury centred orbital insertion on: Friday 5th December 2025.
This was the first of five Mercury encounters on: Saturday 2nd October 2021, BepiColombo passed @ a distance of only 199 KM / 123 miles..
Here various features are seen such as the Astrolabe Rupes under the rising Sun, craters Raphael, Flaubert, Haydn, Bramante and Smetana.
I love these images, give a real sense of being on a spacecraft. The high resolution science cameras were not available right now because they are mounted of the side that is stacked against the MTM (Mercury Transfer Module) but they will be available after the MTM and the MPO (Mercury Planetary Orbiter) separate during final approach in late 2025.
These engineering cameras are that, engineering monitoring, but they take fantastic images of parts of the spacecraft moving in front of the planets Mercury, Venus and Earth during encounters, looking like a space station or crewed craft passing by. Of course the science cameras do not give such a sense as they are obviously unobstructed in their field of views.
Even if the science cameras were available, I would still use the engineering cameras too as they provide a very interesting, almost human viewpoint in addition to the science imagery.
Mercury orbits the Sun once every 87 days, 23 hours and 18 minutes. The orbit around the Sun is quite elliptical and distance from the Sun varies from Perihelion, closest to the Sun @ 46,001,200 KM, mean distance of 57,909,050 KM and Aphelion, furthest from the Sun @ 69,816,900 KM.
Mercury rotates on its axis once every 58 days, 15 hours and 30 minutes. In relation to the Sun though takes 175 days, 22 hours and 36 minutes. Mercury rotates three times for every two orbits around the Sun.
Mercury has a diameter of 4,880 KM / 3,032 miles & a mass of 328.5 billion trillion tons (328.5 followed by twenty zeros).
The surface temperature at the equator varies from minus 186 Celsius at sunrise to 427 Celsius just after hermian noon.
Our own Earth with a diameter of 12,742 KM / 7,917 miles, with a mass of 5,972.2 billion trillion tons (5,972.2 followed by twenty zeros) and a mean density of 5.517 G/CM3.
The following Mercury braking enounters will occur on:
Thursday 23rd June 2022.
Tuesday 20th June 2023.
Thursday 5th September 2024.
Monday 2nd December 2024.
Thursday 9th January 2025.
Hermcentric orbital insertion: Friday 5th December 2025.
End of Primary Mission: Saturday 1st May 2027.
End of possible extended mission: Monday 1st May 2028.
Text: Andrew R Brown.
ESA / JAXA Bepi-Colombo spacecraft.
Text: Andrew R Brown.
ESA / JAXA Bepi-Colombo spacecraft.
The NASA LUCY spacecraft is set to launch early on the morning of: Saturday 16th October 2021 @ 09:34 UTC / 05:34 EDT at Launch Complex 41 at the Kennedy Space Centre, in Florida, USA, to begin a mission to the Jupiter Trojan Asteroids. The launch vehicle is an Atlas 5 in 401 configuration, using four solid fuelled motors and one Centaur liquid fuelled stage provided by ULA / United Launch Alliance.
The Jupiter Trojan Asteroids generally share the orbit around the Sun as Jupiter, but are centred 60 degrees ahead and behind Jupiter. The orbit around the Lagrange points L4 (ahead) and L5 (behind) the giant planet. The L4 group are known as the Greek Camp & the L5 group are known as the Trojan Camp. However both groups are generally collectively known as the Jupiter Trojan Asteroids.
LUCY was named after the early Australopithecus Afarensis, female hominid fossil discovered in Hadar within the Afar Depression, Ethiopia on Sunday 24th November 1974 by Donald Johanson and Tom Gray. LUCY was also named after the Beatles hit Lucy in the sky with diamonds.
After launch at 09:34 UTC on Saturday 16th October 2021, LUCY will go into orbit around the Sun. On Saturday 15th October 2022, LUCY will swing by Earth to get a speed boost to cause the spacecraft to start receding from the Sun, in effect climbing uphill within the gigantic Sun’s gravity well.
Then LUCY will encounter Earth again on Thursday 12th December 2024, for the final gravity boost towards the leading Trojan group known as the Greek Camp.
On the way to the Greek Camp of Jupiter Trojan asteroids, on Sunday 20th April 2025, LUCY will encounter the small 4 KM / 2.4 mile wide Main Belt Asteroid 52246 Donaldjohanson aka 1981 EQ5. The small asteroid was discovered on Monday 2nd March 1981. The asteroid was numbered, but was unnamed until very recently, when it was found that the LUCY spacecraft would be able to encounter this asteroid, it was then given a proper name, named after the discoverer of the hominid in Ethiopia, Donald Johansen. Main Belt Asteroid 52246 Donaldjohanson, has been determined to be a small Type C, Carbonaceous Chondrite asteroid, very primitive, with carbon compounds. Asteroid 52246 Donaldjohanson is thought to be a piece knocked off the 73 KM / 45 mile wide Asteroid 163 Erigone during a giant impact about 130 million years ago. Asteroid 52246 Donaldjohanson is a very slow rotating asteroid, rotating once on its axis once every 10 days & 11 hours or 251 hours. The close up images and spectra will help determine why this is. This will also be an excellent test of the instruments and will be the first new science data from LUCY. Lucy will pass 52246 Donaldjohanson at a distance of 922 KM / 573 miles.
On Sunday 12th August 2027, LUCY will pass the first Trojan Asteroid in the Greek Camp, 3548 Eurybates. This asteroid was discovered on Wednesday 19 September 1973 and was initially dubbed 1973 SO. In fact 3548 Eurybates, was first seen way back in February 1954, but was not followed up and was lost. 3548 Eurybates is a very primitive Type C, Carbonaceous Chondrite asteroid and is 68 KM / 42 miles wide. The rotation period on its axis is about 8 hours and 12 minutes, so LUCY should be able to image most of it with one half at very high resolution. 3548 Eurybates has a tiny moon, since named Quetta. Quetta orbits 3549 Eurybates once every 82 days & 14 hours at a mean distance of 2,310 KM / 1,435 miles and is at most 1 KM / 0.62 mile wide. LUCY will also take detailed images and spectra of Quetta. LUCY will pass 3549 Eurybates at a distance of about 1,000 KM / 621 miles.
Only just over a month later, LUCY will closely encounter the Greek Camp Trojan Asteroid 15094 Polymele on Wednesday 15th September 2027. Asteroid 15094 Polymele was discovered on: Tuesday 17th November 1999. 15094 Polymele is only 21 KM / 13 miles wide, rotates on its axis once every 5 hours & 54 minutes and appears to be very spherical, very unusual for such a small object. 15094 Polymele is one of an extremely rare known P Type asteroid, one of only a 33 known ‘Red Asteroids’. There are carbon compounds as well as silicates. LUCY will pass Asteroid 15094 Polymele at a distance of only 416 KM / 258 miles, allowing for very high resolution images and spectral data. 15094 Polymele appears to be a lone traveller in space, as of October 2021, no moons have been discovered.
On Tuesday 18th April 2028, LUCY will encounter the Asteroid 11351 Leucus. 11351 Leucus is 34 KM / 21 miles wide and is a very primitive D Type asteroid, very carbon rich. One very strange characteristic is the very long rotation period on its axis of 18 days & 8 hours or 440 hours and is certainly very elongated in shape. LUCY will get to see one side only, but in great detail. LUCY will pass 11351 Leucus at a distance of about 1,000 KM / 621 miles. 11351 Leucus appears to be a lone traveller in space, as of October 2021, no moons have been discovered.
On Monday 20th November 2028, LUCY will encounter the Asteroid 21900 Orus. This asteroid is a type C, Carbonaceous Chondrite, and is 54 KM / 34 miles wide. Asteroid 21900 Orus rotates on its axis once every 13 hours & 11 hours. Asteroid 21900 Orus appears to have a very tiny moon, barely 500 metres wide at most. It has only been seen twice in Hubble Space Telescope images in August 2018, but is so faint, that an orbit could not be computed. The Hubble Space Telescope and the upcoming James Webb Space Telescope will carry out further searches. LUCY will pass 21900 Orus at a distance of about 1,000 KM / 621 miles. Any moons will be imaged.
21900 Orus will be the final asteroid in the leading L4 Greek Camp of Jupiter Trojan asteroids to be encountered by the LUCY Spacecraft.
Lucy will then head back for a close Earth gravity assist on Thursday 26th December 2030 / Boxing Day 2030, making LUCY the first spacecraft to return to near Earth space from the outer solar system. The Earth gravity assist will throw LUCY towards the trailing L5 Trojan Camp of Jupiter Trojan asteroids.
Then on Wednesday 2nd March 2033, LUCY will make the one and only planned close encounter with a Trojan Camp Jupiter Trojan. The binary asteroid 617 Patroclus. Both components of this system appear to be very similar in size. The primary 617 Patroclus is 127 KM by 117 KM by 98 KM / 79 by 73 by 60 miles in size. The companion since named Menoetius is slightly smaller at 117 KM by 108 KM by 90 KM / 73 by 67 by 56 miles in size. The orbit around their common centre of gravity, which is slightly closer to the larger component at a distance of 664 KM / 413 miles apart once every 4 days & 6 hours or 102.8 hours. Both are of an extremely rare known P Type asteroid, two of only 33 known ‘Red Asteroids’. There are carbon compounds as well as silicates.
If the LUCY spacecraft continues to operate well (NASA spacecraft tend to last for far longer than planned) then possible further L5 asteroids could be encountered. The LUCY spacecraft is on a cyclical extremely long term heliocentric (Sun Centred) orbit, cycling between both the L 4 and L5 Jupiter Trojans. LUCY is likely to be in this orbit for many millions of years (unless collected in the very far future). Depending on how long LUCY remains operable, there is a chance that several more asteroids could be encountered in both groups as well as in the Main Belt Asteroid Belt.
Text: Andrew R Brown.
NASA / SWRI / Lockheed Martin. Lucy Spacecraft.
Mercury.
Friday 1st October 2021, the BepiColombo spacecraft passed Mercury at a distance of 199 KM / 123 miles, the engineering cameras and many of the scientific instruments were used to gather new images and data on The First Rock from the Sun. Fantastic images, very high quality.
The first Hermean science has been released from this encounter from the science instruments used on board the BepiColombo spacecraft.
The PHEBUS / Probing of Hermean Exosphere By Ultraviolet Spectroscopy, Ultraviolet Spectrometer sampled the extremely tenuous 'atmosphere' or Exosphere of Mercury. Detection of Hydrogen & Calcium were made as the BepiColombo spacecraft exited the deep shadow of Mercury. Whilst both had been observed before by the NASA / JHU / APL MESSENGER / MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft during the hugely successful orbital mission, the PHEBUS on BepiColombo was able to determine that the exosphere was virtually non existent over the cryonically cold Hermean nightside. The suggests that it may well be produced by sunlight acting on the surface chemistry, releasing Hydrogen and Calcium atoms.
The NGNS / Mercury Gamma-ray and Neutron Spectrometer detected peaks as the Gamma Rays from deep space dislodge neutrons and give of Gamma Rays from surface elements within Mercury's regolith and rocky material. This will reveal surface and near subsurface composition. This is being analyzed along with similar data from the Venus encounter back in August.
The Magnetometer also returned useful scientific data. Whilst Mercury's magnetosphere had been well mapped particularly over the northern hemisphere by the NASA / JHU / APL MESSENGER / MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, during the orbital mission, BepiColombo got to sample it over Mercury's southern hemisphere closely. MESSENGER never closely approached Mercury's southern hemisphere as the spacecraft's Hermcentric (Mercury Centred) orbit was very eccentric (for thermal reasons as Mercury;s surface re-radiates a lot of the Sun's energy in infrared and this would over prolonged periods cause MESSENGER to malfunction), with the low Periherm (closest point to Mercury in a Mercury Centred orbit) was over the far northern hemisphere as it was known that Mercury's northern hemisphere had the most interesting geological features, such as the Caloris Basin, etc. MESSENGER was always too far from Mercury when over the southern hemisphere to properly map the magnetosphere.
When BepiColombo eventually achieves Hermcentric orbit, BapiColombo Mercury Planetary Orbiter will stay in a 400 KM / 248 mile high orbit over the whole planet as the spacecraft has a different thermal protection system to that MESSENGER had.
The Magnetometer detected Mercury's magnetosheath, the point immediately behind the Bow Shock were the solar wind crashes into Mercury's magnetosphere and the particles of the solar wind slow down and tumble before being deflected past Mercury.
The ISA / Italian Spring Accelerometer, measures change of speed, and direction of the spacecraft. During this encounter, the ISA detected how the centre of gravity within BepiColombo changed very slightly as the solar arrays very slightly warped as the spacecraft entered and exited the deep. cryonically cold shadow of Mercury. Also the ISA detected the PHEBUS ultraviolet spectrometer, ping back into it's bracket after use.
The video below, also contains the solar wind and engineering data, being converted into sound (there is no sound in space, but fields and particle data as well as vibrations within the spacecraft can be converted to sound). The load 'clump' is the PHEBUS instrument clicking back into it's bracket after use.
https://dlmultimedia.esa.int/.../015/orig-2110_015_AR_EN.mp4
Sound of Mercury's magnetic field. The background tone measures the strength of the magnetosphere, deeper tone, stronger field. The strength of the solar wind is measured by the variable higher pitched tone following the line. The dashed line represents Closest Approach, only 199 KM / 123 miles above the surface of the First Rock from the Sun.
"https://www.youtube.com/embed/ZQAVXrlK0bs?rel=0"
The encounter used the gravity of Mercury to slowly alter the trajectory and reduce the Heliocentric / Sun centred orbital speed towards Mercury, eventually with Hermcentric / Mercury centred orbital insertion on: Friday 5th December 2025.
This was the first of five Mercury encounters on: Saturday 2nd October 2021, BepiColombo passed @ a distance of only 199 KM / 123 miles..
Here various features are seen such as the Astrolabe Rupes under the rising Sun, craters Raphael, Flaubert, Haydn, Bramante and Smetana.
I love these images, give a real sense of being on a spacecraft. The high resolution science cameras were not available right now because they are mounted of the side that is stacked against the MTM (Mercury Transfer Module) but they will be available after the MTM and the MPO (Mercury Planetary Orbiter) separate during final approach in late 2025.
These engineering cameras are that, engineering monitoring, but they take fantastic images of parts of the spacecraft moving in front of the planets Mercury, Venus and Earth during encounters, looking like a space station or crewed craft passing by. Of course the science cameras do not give such a sense as they are obviously unobstructed in their field of views.
Even if the science cameras were available, I would still use the engineering cameras too as they provide a very interesting, almost human viewpoint in addition to the science imagery.
Mercury orbits the Sun once every 87 days, 23 hours and 18 minutes. The orbit around the Sun is quite elliptical and distance from the Sun varies from Perihelion, closest to the Sun @ 46,001,200 KM, mean distance of 57,909,050 KM and Aphelion, furthest from the Sun @ 69,816,900 KM.
Mercury rotates on its axis once every 58 days, 15 hours and 30 minutes. In relation to the Sun though takes 175 days, 22 hours and 36 minutes. Mercury rotates three times for every two orbits around the Sun.
Mercury has a diameter of 4,880 KM / 3,032 miles & a mass of 328.5 billion trillion tons (328.5 followed by twenty zeros).
The surface temperature at the equator varies from minus 186 Celsius at sunrise to 427 Celsius just after hermian noon.
Our own Earth with a diameter of 12,742 KM / 7,917 miles, with a mass of 5,972.2 billion trillion tons (5,972.2 followed by twenty zeros) and a mean density of 5.517 G/CM3.
The following Mercury braking enounters will occur on:
Thursday 23rd June 2022.
Tuesday 20th June 2023.
Thursday 5th September 2024.
Monday 2nd December 2024.
Thursday 9th January 2025.
Hermcentric orbital insertion: Friday 5th December 2025.
End of Primary Mission: Saturday 1st May 2027.
End of possible extended mission: Monday 1st May 2028.
Text: Andrew R Brown.
ESA / JAXA Bepi-Colombo spacecraft.
News has emerged that one of the 7.3 metre wide solar arrays on the LUCY spacecraft has not latched. Engineers are looking at this.
Further news has emerged that the suspected unlatched solar array is indeed unlatched. The power output from this array is only just below full power suggesting it is very nearly fully open, but there is a slight decrease as compared to the fully open latched one.
There will be another attempt to fully open it next week as the software used to open it needs to be reactivated (it was only meant to be run once).
The science payload with the cameras will also be deployed shortly as the spacecraft transits from Safe Mode during and after launch to fully Operational Mode.
LUCY remains healthy & because the launch by the ATLAS 5 from Florida, USA was so accurate, the first scheduled TCM (Trajectory Course Maneuver) burn has been cancelled, thus saving fuel for the mission, possibly can be used for an extended mission to encounter further asteroids.
It is extremely unlikely that this will pose a significant threat to the mission as the LUCY spacecraft is & will remain in a weightless environment. If the array is unlatched, the biggest potential issue that as the LUCY spacecraft is encountering one of the asteroids, during the roll, pitch and yaw maneuvers, the array may 'fold & unfold' back and forth.
LUCY Hominid Fossil & artist's impression of the LUCY Spacecraft encounter with a Jupiter trojan asteroid.
Text: Andrew R Brown.
NASA / SwRI / Lockheed Martin. Lucy Spacecraft.
Sols 1,033 & 1,034. Saturday 23rd & Sunday 24th October 2021.
Mars InSight / Interior Exploration using Seismic Investigations, Geodesy and Heat Transport Lander has come through Solar Conjunction very well.
An Instrument Deployment Camera / IDC test showing mostly the martian mid afternoon sky, another looking down and & couple of Instrument Context Camera / ICC images to the south.
45 degree wide views from the Instrument Deployment Camera / IDC.
120 degree wide views from the Instrument Context Camera of the Seismometer thermal & wind shield and lava plains to the south.
Recap on pre Solar Conjunction findings from Mars InSight Lander.
Very interesting news has come about due to some very recent new detections of Marsquakes.
On Sol 1,000 or Saturday 18th September 2021, Mars InSight detected the strongest and longest lasting Marsquake to date. It measured 4.2 on the Richter Scale. It lasted for nearly an hour & a half.
This was the third of a trio of vastly more powerful Marsquakes detected to date.
On Sol 975 or Wednesday 25th August 2021, Mars InSight detected two quakes, the first at 4.2 and the second at 4.1 on the Richter Scale. The previous record was in May 2019 at 3.7 or about only 20% as strong as the 4.2 one.
Whilst the Marsquake on the 18th September is still being evaluated, much more is known about the two in late August.
The first, more powerful one was the first detected in an area outside of all of the others to date (which are in Cerberus Fossae, about 1,519 KM / 944 miles to the east of Mars InSight), located a much further 8,500 KM / 5,280 miles away.
One possiblilty is from the Valles Marineris, the centre of this gigantic canyon system is some 9,700 KM / 6,027 miles away from Mars InSight. I really hope though it turns out that it is from further north in Tharsis, possibly leading to detection of moving magma under one or more of the gigantic volcanoes. Further work will determine the precise epicentre. If from the Valles Marineris, it is evidence that the rifting process is still happening.
The second quake on the same day was much closer 925 KM / 575 miles from Mars InSight.
These results were only possible because of the success of being able to keep power levels high enough to keep the SEIS / Seismometer active whilst Mars passed though Aphelion or furthest point in it's orbit around the Sun.
If the measures taken had not worked then the SEIS would have been turned off during that whole period, and worse still, Mars InSight could have ceased operating altogether as the batteries flattened and the craft literally would have frozen to death.
Recap of previous update concerning the first major release of data in late July 2021.
New results have been released concerning the Mars InSight / Interior Exploration using Seismic Investigations, Geodesy and Heat Transport Lander which successfully landed on the lava plains within south west Elysium Planitia, Elysium Quadrangle on: Monday 26th November 2018. Interesting results they are too.
The SEIS / Seismometer and the RISE / Rotation and Interior Structure Experiment have determined the following about Mars.
1). Mars has a thinner expected crust, could be locally rather than globally. The crust appears to have at least two sub layers with a total depth of about 20 KM / 12 miles. If the third sublayer is conformed, the depth could be 37 KM / 23 miles.
2). Mars appears to have a mantle 1,540 KM / 957 miles deep, and appears to be fairly uniform in composition and is single layered.
3). Mars also appears to have a molten iron core, also to be an alloy with lighter elements. The core is 3,660 KM / 2,274 miles wide and currently appears to be a single layered core, like the Moon.
4). *All Marsquakes detected to date originate from the Cerberos Fossae area some 1,519 KM / 944 miles to the east. These along with all other Marsquakes detected to date originate within the same area, proving that Cerberus Fossae is a geologically active region, with perhaps magma (unerupted molten rock) moving around deep under the martian crust there. Another possibility is that these fractures could also result from the cooling of the interior of Mars, cracking the crust, much like the Rupes on Mercury.
*Update, three much more powerful Marsquakes have been detected after July 2021, from different locations. See beginning of post.
LMST = Local Mars Standard Time in western Elysium Planitia.
Note how the plains of Elysium Planitia here are remarkably similar to those in SW Utopia Planitia some 1,922 KM / 1,194 miles away as seen by the China National Space Administration / CNSA Zhurong Rover.
Power issues have been a huge concern for Mars inSight in recent months as the solar arrays have become increasingly coated in dust and Mars has just passed through Aphelion, the furthest point from the Sun at a distance of about 250.50 million KM / 156.65 million miles from the Sun. Mars at Aphelion occurred on: Tuesday 13th July 2021.
The next Mars Perihelion (closest point to the Sun) will occur on: Tuesday 21st June 2022.
Firstly the dust issue has been somewhat alleviated by a very balsy but appearing to be largely successful plan of the scoop to dump small quantities of duricrust on the deck next to the arrays and allowing the winds to pick up particles from the duricrust, blow them across the arrays knocking off dust particles. It is working and the power output from the arrays has increased a little and continuing to do so.
The powering down of the science instruments is now not required as the above campaign was highly successful. The fourth rock from the Sun is now well past Aphelion and an increase in power has been detected. Looks like Mars InSight will be able to complete the extended mission. The more seismic & RISE data, the better for sure. The cameras too can keep capturing images.
It was hoped that dust devils would at times pass over InSight and they would remove dust from the solar panels. This happened fairly frequently with the Mars Exploration Rovers, MER A Sprit and MER B Opportunity as well as the Phoenix Mars Lander. All three had vastly extended operational missions in part due to this.
However, this has not happened with Mars InSight Lander.
Whilst it was late Spring in the northern hemisphere on Mars, (InSight landed at about 4.5 North, well within the martian tropics between the equator and the Tropic of Aquarius, Mars's northern tropic), the increased distance towards Aphelion is offsetting the higher rising Sun. It was the Martian Solstice, northern Summer, southern Winter on: Tuesday 25th August 2021.
On Wednesday 29th September 2021, the final set of instructions was sent to Mars InSight to allow for continued data acquisition and on board storage of said data whilst Mars undergoes Solar Conjunction on Thursday 7th October 2021. Mars then to all intents passed behind the Sun as viewed from Earth. Communication with all Mars spacecraft will not be possible for about two weeks. Mars InSight is returning recorded data since shortly after coming out of Solar Conjunction in mid October. Will be interesting to see if other large Marsquakes are detected during the short period when communication was not possible.
Text: Andrew R Brown.
IRIS / Incorporated Research Institutions for Seismology. Earth & Mars.
NASA / JPL-Caltech. Mars InSight.
Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
Mars Science Laboratory Curiosity.
Sol 3,278. Tuesday 26th October 2021.
MSL Curiosity is back working after successfully coming out of Solar Conjunction when Mars more or less passed behind the Sun from the viewpoint on Earth.
HazCam / Hazard Cameras views: 120 degrees wide.
NavCam / Navigation Cameras views: 45 degrees wide.
HazCam / Hazard Cameras & NavCam / Navigation Cameras view of the surroundings on the flanks of Aeolis Mons aka Mt Sharp.
Looking around.
One view looking back shows the MMRTG / Multi Mission Radioisotopic Thermoelectric Generator (uses heat from the natural radioactive decay of Plutonium 238 to generate electrical power, not undergoing nuclear reactions) on board Mars Science Laboratory Curiosity Rover. The half life of Plutonium 238 is 87.7 years, is element # 94 & atomic weight 238.04.
Plutonium 238 has 94 Protons, 144 Neutrons, 94 Electrons and slowly decays to become Uranium 234 on it's way to eventually becoming Lead.
Also looking up towards the summit of Aeolis Mons, informally known as Mt Sharp.
MSL Curiosity was climbing the 5,500 metre / 18,044 foot tall Aeolis Mons aka Mt Sharp, in turn inside the 4,850 metre / 15,900 foot deep and 154 KM / 96 mile wide Gale Crater, within the Aeolis Quadrangle on Mars.
Mars Science Laboratory Curiosity continues to operate flawlessly and the wheels which show damage after nearly nine years on the martian surface still have many kilometres left in them.
Front & Rear Hazard Cameras & NavCams / Navigation Cameras.
Text: Andrew R Brown.
NASA / JPL / Malin Space Science Systems. Mars Science Laboratory Curiosity.
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RASNZ
Royal Astronomical Society of New Zealand
eNewsletter: No. 250, 20 October 2021
Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website www.rasnz.org.nz in their own newsletters provided an acknowledgement of the source is also included.
Contents
1. Gareth Davies Receives IDA's Dark Sky Defender Award
2. RASNZ Beanies
3. RASNZ 2022 Calendar
4. 2021 Burbidge Lecture - Online Monday, November 8
5. The Solar System in November
6. Lunar Eclipse Broadcast
7. Variable Star News
8. List Your Observatory to Help Combat Obtrusive Lighting
9. Star Parties around Aotearoa
10. eVscope eQuinox Telescopes Available
11. ESO Images Some of the Biggest Asteroids
12. Mysterious Radio Signals from Near the Milky Way's Centre
13. Pluto's Atmosphere Freezing Out
14. 'Young' Moon Rocks Found
15. Quote
1. Gareth Davies Receives IDA's Dark Sky Defender Award
RASNZ and Auckland Astronomical Society member, Gareth Davies, is this year's recipient of International Dark Sky Association's (IDA) Dark Sky Defender Award - https://www.darksky.org/announcing-the-2021-award-recipients/
He has been an understated but effective dark sky advocate since 2017 having been a part of the accreditation team of Aotea/Great Barrier Island Dark Sky Sanctuary; providing sky quality monitoring for Aotea/Great Barrier Island Dark Sky Sanctuary, Waiheke Island, Waitakere Ranges, Naseby and Rakiura/Stewart Island Dark Sky Sanctuary; providing Dark Sky Ambassador training for Aotea/Great Barrier Island Dark Sky Sanctuary, Rakiura/Stewart Island Dark Sky Sanctuary and Fiordland and providing advisory inputs to Elan Valley Dark Sky Park in Wales. He is one of the instructors of Aotearoa Astro-tourism Academy (https://aaanz.org/) and during the recent lockdown, together with John Drummond, he has launched The Kiwi Astronomers YouTube Channel (https://www.youtube.com/channel/UCz71UT575Hp26LxYyNqKXuA/featured) and Podcast (https://thekiwiastronomers.podbean.com) - both vehicles to promote the enjoyment of New Zealand's dark skies.
2. RASNZ Beanies
Astronz advises that a limited stock of the RASNZ Centennial Beanies have arrive in and are now available on the Astronz website at
https://astronz.nz/products/rasnz-centenary-beanie .
3. RASNZ 2022 Calendar
Astronz has partnered with RASNZ to produce a calendar for 2022.
Featuring the very best of New Zealand astrophotography with some of the best images from the 2021 NZ Astrophotography Competition and astronomical events during 2022.
The calendar will be available from early November. Discounts will be available to astronomical societies for bulk purchases.
For more information contact Astronz at sales@astronz.nz or phone 09 473 0203.
4. 2021 Burbidge Lecture - Online Monday, November 8
The Auckland Astronomical Society's 2021 Burbidge Lecturer is Hannah Wakeford, University of Bristol, UK. Her lecture title is 'Diving Through Exoplanet Atmospheres'
With the lockdown restrictions the lecture will now be online. All are welcome to join this event on Monday, 8th November at 8pm at https://www.youtube.com/AucklandAstronomicalSociety
Lecture abstract:
The study of exoplanets, planets that orbit stars other than the Sun, is fascinating new field of research. The question “how do stars and planetary systems form and evolve?”” is one of the biggest in Astronomy, and is at the root of one of the most important questions in science today: “How did we get here?”. I will take us on a journey to explore how we measure and understand the nature these strange new worlds beyond our Solar System. We will dive into the atmospheres of alien planets to discover the truly wild nature of planets in the universe from chains of rocky worlds around ultra-cool stars, to exotic clouds of molten rock in the atmosphere of ultra-hot gas giants. Hannah Wakeford is a lecturer in Astrophysics at the University of Bristol, UK where she leads a group researching the atmospheres of exoplanets using observations from space telescopes. Hannah’s work focuses on the exotic clouds of giant hot Jupiters, down to chains of small rocky worlds around ultra-cool stars. She studied for a Masters in Planetary and Space Physics at Aberystwyth University with field studies in Svalbard to measure the aurora, and completed her PhD thesis on exoplanets at the University of Exeter before heading to the USA to work at NASA and STScI. Alongside her research she runs the monthly podcast Exocast all about exoplanet science and hosts the #ExoCup twitter competition for the public to crown the champion exoplanet of the year.
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The lecture will be followed by the announcement of the New Zealand Astrophotography Competition Results and winner of the Harry William Trophy.
5. The Solar System in November
Dates and times shown are NZDT (UT + 13 hours). Rise and Set times are for Wellington. They will vary by a few minutes elsewhere in NZ. Data is adapted from that shown by GUIDE 9.1.
A partial eclipse of the moon occurs in the evening of November 19. At maximum eclipse just after 10pm, 97.6% of the moon is immersed in the Earth’s shadow. The moon begins to enter the Earth full shadow at 9.19pm, close to the time of moon rise in NZ. It finally leaves the shadow at 12:48 am
THE SUN and PLANETS in NOVEMBER, Rise & Set, Magnitude & Constellation
NOV 1 NZDT NOV 30 NZDT
Mag Cons Rise Set Mag Cons Rise Set
SUN -26.7 Lib 6.05am 8.04pm -26.7 Oph 5.40am 8.38pm
Mercury -0.8 Vir 5.35am 6.38pm -1.3 Oph 5.38am 8.43pm
Venus -4.6 Oph 8.26am 12.13am -4.9 Sgr 8.29am 11.54pm
Mars 1.7 Vir 5.46am 7.20pm 1.6 Lib 4.45am 7.08pm
Jupiter -2.5 Cap 1.20pm 3.18am -2.3 Cap 11.39am 1.30am
Saturn 0.6 Cap 12.01pm 2.33am 0.7 Cap 10.15am 12.44am
Uranus 5.6 Ari 8.10pm 6.28am 5.7 Ari 6.10pm 4.31am
Neptune 7.8 Aqr 3.43pm 4.25am 7.9 Aqr 1.48pm 2.31am
Pluto 14.6 Sgr 10.52am 1.56am 14.6 Sgr 9.01am 12.04am
NOV 1 NZDT NOV 30 NZDT
TWILIGHTS morning evening morning evening
Civil: start 5.38am, end 8.32pm start 5.10am, end 9.09pm
Nautical: start 5.02am, end 9.08pm start 4.29am, end 9.51pm
Astro: start 4.23am, end 9.47pm start 3.41am, end 10.39pm
NOVEMBER PHASES OF THE MOON, times NZDT & UT
New Moon: Nov 5 at 10.15am (Nov 4, 21:15 UT)
First quarter: Nov 12 at 1.46am (Nov 11, 12:46 UT)
Full Moon: Nov 19 at 9.57pm (08:57 UT)
Last quarter Nov 28 at 1.28am (Nov 27, 12:28 UT)
THE PLANETS in NOVEMBER 2021
VENUS is a brilliant object in the evening sky, on the 1st setting just after 12 midnight, NZDT. During November the fraction of the planet illuminated by the Sun, as seen from Earth decreases, from 48% to 29%, but even so it becomes more brilliant.
MERCURY, in the morning sky, rises only half an hour before the Sun on the 1st. It reaches superior conjunction at the far side of the Sun on the 29th, so is unobservable all month.
MARS is even closer to the Sun than Mercury at first. The two planets are only 1° apart on the 10th, a conjunction which will be extremely difficult to see. By the end of the month Mars will be a little further from the Sun, but still a difficult morning object.
JUPITER and SATURN are both easily visible in the evening sky, setting after midnight.
The moon passes Saturn on the 10th, when they will be 5° apart before midnight. The following evening the moon at first quarter, will be rather further from Jupiter.
URANUS, NEPTUNE and PLUTO continue to move into the evening sky with first Neptune and then, later in the month, Uranus rising well before sunset.
POSSIBLE BINOCULAR ASTEROIDS in NOVEMBER
NOV 1 NZDT NOV 30 NZDT
Mag Cons transit Mag Cons transit
(1) Ceres 7.7 Tau 3.15am 7.1 Tau 12.55am
(2) Pallas 9.5 Aqr 9.24pm 9.8 Aqr 7.39pm
(4) Vesta 7.8 Lib 1.09pm 7.6 Sco 2.02pm
(7) Iris 9.1 Gem 6.30am 8.6 Cnc 4.52am
CERES starts November close to Aldebaran. The asteroid is closest to the star on the 3rd when the two are only 7 arc-minutes apart with Ceres to the south of the star. They will then rise about 10pm NZDT. Over the rest of the month Ceres will move through the Hyades cluster and beyond. It rises just before 7pm by the 30th
PALLAS is an evening object in Aquarius. It is stationary at the start of the month. The asteroid subsequently moves to the east rising just before 1pm on the 30th.
VESTA is close to the Sun all month with a conjunction on the 29th when they are less than a degree apart.
IRIS is a morning object starting November in Gemini but moving on into Cancer on the 4th. Iris is stationary on the 30th, at the start of its retrograde movement. It will then rise at 11.50 pm.
-- Brian Loader
6. Lunar Eclipse Broadcast
Astronz will be broadcasting a live feed of the Lunar Eclipse on 19th November (weather permitting) from Torbay, Auckland on YouTube
https://youtu.be/0y2TPIypS7I
7. Variable Star News
A couple of American Association of Variable Star Observers webinars of particular interest.
The AAVSO’s October “How to Hour” in early October was presented by Gary Billings (AAVSO Eclipsing Binaries Observing Section co-chair) on "Eclipsing Binaries and O-C Diagrams". This webinar is now available from the AAVSO site (AAVSO October Communication). Viewing time for this Video is 1hr 45min. https://www.youtube.com/playlist?list=PLnZ_rvnR35re3ZxnumCnIesanWvUyy9eB
This link accesses the library of all 2021videos available, 25 as at mid-October.
On Saturday the 23rd, at 18:00 UT, the second of two on-line presentations is by Dr. Mario Motta (Tufts University School of Medicine, American Medical Association) 'Dark and Quiet Skies', a UN effort at light pollution control and more. The link is https://aavso.us10.list-manage.com/track/click?u=3ad9dedd265a0351968ebddee&id=9dc72c914d&e=e75acde184 .
-- Alan Baldwin.
8. List Your Observatory to Help Combat Obtrusive Lighting
From RASNZ President Steve Butler -
If you own or operate an astronomical observatory in New Zealand, we would like to list this on the RASNZ Website. We will limit
details if you wish its specific location kept quiet. A recently updated Australia / New Zealand Standard on Control of the obtrusive
effects of outdoor lighting says the RASNZ will list observatories. This will allow local government planners to include protections
if required. Please have a look at https://www.rasnz.org.nz/nzo or email observatory@rasnz.org.nz with information or to ask
questions.
-- From Keeping in Touch #48, 14th October 2021.
9. Star Parties around Aotearoa
CENTRAL STAR PARTY. Thu 6th–Mon 10th January 2022. Four days/nights of tenting/bunk rooms, excellent astronomy talks and telescope viewing! Many daytime activities in the surrounding Hawkes Bay. Tuki Tuki Camp site, 70 Moore Rd, Haumoana, Hawkes Bay. https://censtar.party/ .
STARDATE – SOUTH ISLAND. Fri 4th-Mon 7th Feb 2022 (Waitangi Weekend). Staveley (112km from Christchurch, inland from Ashburton). Awesome daytime speakers, three nights of viewing under a beautifully dark sky, and a potluck dinner on Saturday night. There's accommodation on site with bunkrooms, campervan sites, and tent sites. See http://www.treesandstars.com/stardate/ .
STARDATE. Fri 4th-Sat 5th February 2022 (Waitangi Weekend), at Stonehenge. Phoenix Astronomical Society. Contact
secretary@astronomynz.org.nz . The Phoenix Astronomical Society is holding its Stardate over Waitangi Weekend 2022 at Stonehenge Aotearoa, Carterton in the Wairarapa. A particular aspect of the weekend will be celebration of the henge itself. Details will be continually updated on http://www.astronomynz.org/meetings-and-events.html
THE DARK SKIES RETREAT. Thu 23rd–Sun 26th June 2022, proudly supported by ASTRONZ. A weekend getaway of astronomical proportions! Astronomy, astrophotography, night sky education, science outreach, with a big focus on dark skies. Held over the first Matariki Public Holiday in June. Held under the beautiful dark skies of Camp Iona, Herbert Forrest, Herbert (20-minutes south of Oamaru). Contact Damien McNamara, solaur.science@gmail.com .
There is no Foxton Beach Camp astrophotography camp this year due to COVID-19 uncertainty.
-- From Keeping in Touch #48, 14th October 2021.
10. eVscope eQuinox Telescopes Available
Astronz advises:
eVscope eQuinox - Now Available in NZ.
Powerful Digital Telescope
View deep sky objects and do citizen science with this smart, fast, portable, connected device.
Special launch offer, limited stock, this offer will sell out fast.
Pre-order now via website https://astronz.nz/collections/telescopes/products/evscope-equinox
Astronz: NZ Distributor for Unistellar.
11. ESO Images Some of the Biggest Asteroids
Using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in Chile, astronomers have imaged 42 of the largest objects in the asteroid belt, located between Mars and Jupiter. Never before had such a large group of asteroids been imaged so sharply. The observations reveal a wide range of peculiar shapes, from spherical to dog-bone, and are helping astronomers trace the origins of the asteroids in our Solar System.
“Only three large main belt asteroids, Ceres, Vesta and Lutetia, have been imaged with a high level of detail so far, as they were visited by the space missions Dawn and Rosetta of NASA and the European Space Agency, respectively,” explains Pierre Vernazza, from the Laboratoire d’Astrophysique de Marseille in France, who led the asteroid study published on October 12 in Astronomy & Astrophysics. "Our ESO observations have provided sharp images for many more targets, 42 in total."
The previously small number of detailed observations of asteroids meant that, until now, key characteristics such as their 3D shape or density had remained largely unknown. Between 2017 and 2019, Vernazza and his team set out to fill this gap by conducting a thorough survey of the major bodies in the asteroid belt.
Most of the 42 objects in their sample are larger than 100 km in size; in particular, the team imaged nearly all of the belt asteroids larger than 200 kilometres, 20 out of 23. The two biggest objects the team probed were Ceres and Vesta, which are around 940 and 520 kilometres in diameter, whereas the two smallest asteroids are Urania and Ausonia, each only about 90 kilometres.
By reconstructing the objects’ shapes, the team realised that the observed asteroids are mainly divided into two families. Some are almost perfectly spherical, such as Hygiea and Ceres, while others have a more peculiar, “elongated” shape, their undisputed queen being the “dog-bone” asteroid Kleopatra.
By combining the asteroids’ shapes with information on their masses, the team found that the densities change significantly across the sample. The four least dense asteroids studied, including Lamberta and Sylvia, have densities of about 1.3 grams per cubic centimetre (g/cu.cm), approximately the density of coal. The highest, Psyche and Kalliope, have densities of 3.9 and 4.4 g/cu.cm, respectively, which is higher than the density of diamond at 3.5 g/cu.cm.
This large difference in density suggests the asteroids’ composition varies significantly, giving astronomers important clues about their origin. “Our observations provide strong support for substantial migration of these bodies since their formation. In short, such tremendous variety in their composition can only be understood if the bodies originated across distinct regions in the Solar System,” explains Josef Hanuš of the Charles University, Prague, Czech Republic, one of the authors of the study. In particular, the results support the theory that the least dense asteroids formed in the remote regions beyond the orbit of Neptune and migrated to their current location.
These findings were made possible thanks to the sensitivity of the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument mounted on ESO’s VLT. All observations were conducted with the Zurich IMaging POLarimeter (ZIMPOL), an imaging polarimeter subsystem of the SPHERE instrument that operates at visible wavelengths.
Astronomers will be able to image even more asteroids in fine detail with ESO’s upcoming Extremely Large Telescope (ELT), currently under construction in Chile and set to start operations later this decade. ELT observations of main-belt asteroids will allow study of objects with diameters down to 35 to 80 kilometres, depending on their location in the belt, and craters down to approximately 10 to 25 kilometres in size.
A SPHERE-like instrument at the ELT would even allow imaging of a similar sample of objects in the distant Kuiper Belt, giving a geological history of a much larger sample of small bodies from the ground.
See the original press release with asteroid pictures and references at https://www.eso.org/public/news/eso2114/
-- Thanks to Karen Pollard for forwarding the press release.
12. Mysterious Radio Signals from Near the Milky Way's Centre
What suddenly gets bright in the sky, sends out random radio signals and then disappears for months? It's a question that has stumped astronomers since the discovery of a mysterious radio signal coming from near the centre of our galaxy in January last year.
Astronomers have detected a strange radio signal seven times in nine months using the ASKAP telescope in Western Australia. The signal has also been detected by the MeerKAT telescope in South Africa. The astronomers are not sure what caused the signal, but it may come from a rare group of mysterious objects.
The signal is so strange it may be coming from a new type of celestial object, an international team of astronomers report in The Astrophysical Journal [around October 13].
The team first picked up the signal while scanning the sky with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in outback Western Australia. The signal appeared another four times in a row in just a couple of weeks, said study co-author Tara Murphy of the University of Sydney. "That's when we were starting to think, 'OK, this is a real thing.'" Then the signal from the source dubbed ASKAP J173608.2-321635 disappeared, reappearing a couple of times a few months later.
"Sometimes it seems to stay on, detectable for days or weeks at a time, and then other times it can come on and off in a single day, which is extremely fast for an astronomical object," Professor Murphy said.
Not only is the timing random, but the signal can vary in strength, becoming 100 times brighter in the radio spectrum. Even more weirdly, the radio waves are aligned in one direction that rotates as the signal travels through the universe towards us. "That rules out almost all astronomical objects we know of," Professor Murphy said. But that doesn't mean we've suddenly detected aliens.
In the months following the initial discovery, the team led by PhD student Ziteng Wang explored a number of options trying to work out what the source was. "It's a bit like a detective story trying to rule out all these different possibilities," Professor Murphy said. They narrowed it down to three. The first option was a pulsar — the fast-spinning heart of a dead star, which regularly send out very fast pulses of energy like clockwork.
The team turned to the Parkes Radio Telescope, which is famous for detecting pulsars, but found nothing that could be the source. So then they went to the MeerKAT radio telescope in South Africa, which can detect not only pulses, but take images of signals. They saw nothing for three months, but in February this year they detected a single signal that was almost as strong as the original signal, before fading away.
Even though the signal had some of the properties of a pulsar, there were no tell-tale fast pulses.
Space telescopes also found no objects emitting light in the X-ray and infrared ranges in the area that would indicate the source was a pulsar or another type of dead, fast-spinning star known as a magnetar.
The second possibility the team explored was whether the signal could have come from a massive flare from a star. "This object was so bright that if it was a star, we should be able to see it in visible light," Professor Murphy said. "But … we didn't see it at all, it was completely invisible. So then we've got this situation where we've ruled out the two most likely explanations."
Is it a 'cosmic burper'? The only other possibility is that it belongs to a rag-tag group of rare objects known as galactic centre radio ransients, one of which is dubbed the "cosmic burper". "It could be that we've discovered one of these, so in a way that's exciting, because there are very few of them known, but also frustrating because we don't actually know what galactic centre radio transients actually are," Professor Murphy said.
Every single galactic centre radio transient that has been discovered is slightly different; while some emit regular pulses of radio waves, others don't. "All of [this object's] properties are slightly different to all of the ones that are known, but the thing is they are all different to each other," Professor Murphy said. So although they are all lumped in the same category, we don't know enough about them to tell if they are related at all. "They all might just be unknown variable polarised objects near the centre of the galaxy," Professor Murphy said.
Transient objects are very hard to spot because they only turn on for a short amount of time, said Gemma Anderson, an astrophysicist at Curtin University and the International Centre for Radio Astronomy Research, who was not involved in the study. "You want to hope your telescope is pointing at the right part of the sky when it is turning on, because it may not appear again for weeks, months or ever," Dr Anderson said.
And unlike transient objects that emit pulses of energy in the X-ray, optical or infrared wavelengths, objects that only emit radio waves are very difficult to detect. But the advent of radio telescopes such as ASKAP Pathfinder and MeerKAT have enabled us to peer further into the universe than ever before.
"ASKAP is particularly powerful because it looks at such a large part of the sky in one go," Dr Anderson said. "In Australia, we are now looking at the universe in a new way that hasn't been possible until now.
"This transient that this team has found is the tip of the iceberg."
The ASKAP and MeerKAT telescopes are the first stages of the world's largest radio telescope, the Square Kilometre Array (SKA).
When the SKA comes on board, it may be possible to find even fainter transient objects "of which there could be tens, hundreds, thousands of them in our galaxy that have remained hidden," Dr Anderson said.
Professor Murphy said she hoped the team would find more objects like this with the ASKAP telescope. "Then by building up a statistical number of them, we'll be able to work out what they are. "That's how things often happen in astronomy; you find one rare thing, then you find more like it and eventually you can actually understand what's going on."
See Genelle Weule's original article at https://www.abc.net.au/news/science/2021-10-13/mysterious-radio-signals-detected-milky-way-galaxy/100526070
-- Thanks to John Knox for passing along the link.
13. Pluto's Atmosphere Freezing Out
Pluto's atmosphere is going through a transformation, scientists are finding.
The icy dwarf planet, which lies over 4.8 billion km away from Earth in the Kuiper Belt, got astronomers' attention as it passed in front of a star back in 2018. With the star backlighting Pluto, the team of researchers was able to make observations of the dwarf planet and its atmosphere. With this unique view, they concluded that Pluto's atmosphere is starting to disappear.
Using telescopes at multiple sites in both the U.S. and Mexico, the team observed Pluto and its thin atmosphere, which is primarily made of nitrogen, like that of Earth. Pluto's atmosphere is supported by the vapour pressure of ices on the dwarf planet's surface. So, if ice warms up on Pluto, it can dramatically alter the density of its atmosphere, according to a statement from Southwest Research Institute (SwRI), the home institution of multiple members of the research team.
For about 25 years, Pluto has been moving farther and farther away from the sun, so its surface temperature has been going down. And with these recent observations, the researchers found evidence showing that Pluto's atmosphere is actually refreezing back onto its surface as the dwarf planet gets colder. Pluto is so far from the sun that, as time goes on, it will get distinctly farther away (and colder) before getting closer to the sun in other regions of its immense orbit.
Thanks to a phenomenon known as thermal inertia, Pluto's surface pressure and atmospheric density continued to rise until 2018. Essentially, Pluto had residual heat from when it was closer to the sun. However, the inertia starting to wear off and, as Pluto gets colder, more and more of its atmosphere will freeze back onto its surface and "disappear."
"An analogy to this is the way the sun heats up sand on a beach," SwRI staff scientist Leslie Young, who studies the interaction between icy solar system bodies and their surfaces and atmospheres, said in the same statement. "Sunlight is most intense at high noon, but the sand then continues soaking up the heat over the course of the afternoon, so it is hottest in the late afternoon. The continued persistence of Pluto’s atmosphere suggests that nitrogen ice reservoirs on Pluto’s surface were kept warm by stored heat under the surface. The new data suggests they are starting to cool," Young said.
So how did they figure this out just by watching Pluto move in front of a star? The researchers watched the star fade as Pluto moved in front of it and then come back into view once the dwarf planet had passed. Using the rate that the star came in and out of view, a transition that lasted about 2 minutes, they were able to determine the density of the dwarf planet's atmosphere, according to the statement.
This method relies upon what is known as an "occultation," an event that happens when one cosmic object is hidden by another passing in front of it. Studying occultations is an old and well-known technique in astronomy, and researchers have used it to study Pluto's atmosphere since 1988, Eliot Young, a SwRI senior program manager, said in the statement.
"The New Horizons mission obtained an excellent density profile from its 2015 flyby, consistent with Pluto’s bulk atmosphere doubling every decade, but our 2018 observations do not show that trend continuing from 2015," Young added, referring to the pioneering NASA mission that gave the world its first up-close look at Pluto.
In observing Pluto as it passed in front of the star, the team noticed a "central flash" in the middle of the path of the dwarf planet's shadow. The flash, caused by Pluto's atmosphere refracting light into the centre of the shadow, changed the light curve that usually happens during occultation from a "u-shape" into a "w-shape." "The central flash seen in 2018 was by far the strongest that anyone has ever seen in a Pluto occultation," Young said. "The central flash gives us very accurate knowledge of Pluto’s shadow path on the Earth."
Young discussed the results of this study Oct. 4 at the 53rd American Astronomical Society Division for Planetary Sciences Annual Meeting.
From Chelsea Gohd's article at http://r.smartbrief.com/resp/osoICKoOsPDqzGwHCifOtUBVNNNb?format=multipart
See also https://www.syfy.com/syfywire/we-got-to-pluto-just-in-time-its-air-is-starting-to-freeze-out
14. 'Young' Moon Rocks Found
China’s Moon trip revealed surprisingly recent volcanic activity. The Chang’e-5 mission returned the first lunar samples since the 1970s, with bits of lava dated at two billion years old.
The first samples to be brought back from the Moon in half a century — and the first ever by a Chinese mission — carry evidence of the most recent lunar lava ever analysed. Researchers used only tiny fragments from the two kilograms of rock returned last December by the Chang’e-5 lander to confirm predictions about the Oceanus Procellarum region, where the spacecraft had landed.
At about two billion years old, the samples reveal volcanism that is at least one billion years younger than any found by NASA’s Apollo astronauts or by the Soviet Union’s uncrewed Luna missions in the 1960s and 1970s. “This is the youngest-ever lava flow dated from the Moon,” says Katherine Joy, a planetary scientist at the University of Manchester, UK, and a co-author of the study, published in Science on 7 October (Reference 1.) The findings fill a vital gap in the Moon’s geology, and will also help scientists to understand the history of other Solar System bodies.
China achieved a historic feat when its Chang’e-5 lander touched down on the Moon on 1 December 2020, scooped up samples of the lunar surface and lifted off again two days later. It then performed an automated rendezvous with its mother ship in lunar orbit, which subsequently flew back to Earth. A re-entry capsule carrying the samples landed in China’s Inner Mongolia region on 16 December.
The mission’s target, Oceanus Procellarum on the Moon’s near side, is a region of interest to scientists because it is thought to contain young solidified lava, an indication of relatively recent volcanism on the Moon.
Based on samples returned by the Apollo and Luna programmes, scientists already had evidence for volcanic eruptions on the Moon stretching back more than 4 billion years, with the majority occurring between 3.8 billion and 3 billion years ago. But no mission had landed in an area as young as Oceanus Procellarum — Latin for ‘Ocean of Storms’ — which stretches 2,500 kilometres from north to south. Lunar scientists were eager to try to find evidence of more recent volcanism in a region such as this. “I was very pleased with the selection of this landing site,” says Harald Hiesinger, a planetary scientist at the University of Münster in Germany.
As on Earth, lunar volcanism is thought to occur when magma is pushed up to the surface and erupts, leaving ‘seas’ (maria in Latin) of basaltic rock on the surface, which are easily seen from Earth. In Oceanus Procellarum, nearly 2,000 cubic kilometres of basaltic magma are thought to have spewed on to the surface, a big eruption by lunar standards.
The Chang’e-5 lander used a scoop and a drill to collect samples here, at least some of which are now known to be basaltic rock, and their age was determined by radioactive dating.
The findings provide a vital data point about the history not just of the Moon, but of the wider Solar System too. By knowing the exact age of Oceanus Procellarum, and matching that to the number of its craters — which accumulate over time as impacts occur — scientists can infer that locations on other worlds, such as Mars, with similar numbers of craters are of a comparable age. This process, known as crater counting, has so far relied almost entirely on the dating of lunar samples collected by the Apollo missions, leaving a huge gap in the timeline between one and three billion years ago. “It’s absolutely essential to get more data points,” says Ian Crawford, a planetary scientist at Birkbeck, University of London. “That’s what this paper has done.”
What’s unclear at the moment, however, is what would have driven volcanism on the Moon at the time when Oceanus Procellarum formed. By this time, the Moon had begun to cool, and “the amount of magma being generated dropped off quickly”, says Joy. One possibility is that residual radioactive uranium, thorium and potassium in the Moon’s interior provided the heat necessary for late volcanism to occur. But the Chang’e-5 samples do not show an abundance of such radioactive elements. “This is really a puzzle,” says Joy.
Another explanation might be that the tidal pull of Earth’s gravity gave the Moon the necessary heat. “Two billion years ago, the Moon was significantly closer to Earth, maybe halfway closer than it is now,” says Alexander Nemchin, a planetary scientist at Curtin University in Perth, Australia, and a co-author of the study. “So this effect was probably amplified quite significantly.” However, it’s not clear why this would produce localized heating in regions like Oceanus Procellarum, and not much more widely across the lunar surface.
There could be even younger areas to be found on the Moon. Hiesinger, who has contributed to much of the crater-counting work, says that some regions appear to be just a few tens or hundreds of millions of years old — which poses a conundrum. “That would mean the Moon was volcanically active until about 50 million years ago,” he says, which seems “highly unlikely”.
See the original article by Jonathan O'Callaghan with pictures and reference at https://doi.org/10.1038/d41586-021-02744-8
15. Quote - Repurposed Latin
Pro rata - native tree advocate.
Camera obscura - a hidden camera is operating.
Ad infinitum - Freeview television.
Non sequitur - I've lost the pruning shears.
-- from the NZ Listener, 22 May 2021, p.57.
Alan Gilmore Phone: 03 680 6817
P.O. Box 57 alan.gilmore@canterbury.ac.nz
Lake Tekapo 7945
New Zealand
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December Celestial Calendar by Dave Mitsky
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Minor Planet Occultation Updates:
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