Astroboffins think strangely porous boulders found on asteroid Ryugu may be the stuff of proto-planets
(2021/05/26)
- Reference: 1622016004
- News link: https://www.theregister.co.uk/2021/05/26/ryugu_poros_boulders/
- Source link:
Asteroid Ryugu, the rock from which Japan’s Hayabusa2 probe brought home some samples, is home to highly porous boulders that might just have been the stuff of which planets were made.
So says a new [1]paper titled “Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body” published on May 24th in Nature Astronomy .
The paper is based on observations of the asteroid, not analysis of samples returned by Hayabusa2.
[2]
[3]
[4]
As [5]explained in a Japan Aerospace Exploration Agency (JAXA) summary of the paper, Hayabusa2 used its Thermal Infrared Camera and the infrared radiometer carried by its Mobile Asteroid Surface Scout (MASCOT) lander to get a look at Ryugu’s rocks.
They found that many of the rocks on Ryugu’s surface have low thermal inertia – a measure of how quickly they can be warmed or cool. Low thermal inertia indicates low density or high porosity.
[6]
Global map of Ryugu captured during descent
to Ryugu and used in this paper. Click to enlarge
JAXA’s summary of the paper describes images captured by the probe as depicting material “similar to a pumice stone used to remove dead skin cells on your foot.” By doing so it means, dear reader, that you have discovered something about asteroid rocks and astroboffins’ grooming habits of.
High porosity has also been observed in the core of comets, which are thought to be relics of the “planetesimals” – the balls of dust and rock that agglomerated and may eventually have grown into planets.
[7]Japan accuses Chinese military of cyber-attacks on its space agency
[8]Japan sticks the landing: Asteroid sample recovered from Hayabusa2 probe
[9]Japanese probe to land asteroid rock sample in Australia on December 6th
[10]BEHOLD! Japan's Hayabusa2 probe left human imprints on ASTEROID SAND
The paper’s many authors suggest that the stuff found on Ryugu are remnants of planetismals that never got big enough for gravity and pressure to squish their component parts into planets. They suggest that the porosity is intrinsic, and not the result of impacts with Ryugu or cracking, and that the asteroid therefore has a lot to teach us about how planets formed in our Solar System.
JAXA’s summary holds out some hope that the samples it holds will be found to contain material with the same porosity observed by other instruments.
Data used by the paper's authors is available [11]here , if you want the chance to draw your own conclusions. ®
Get our [12]Tech Resources
[1] https://www.nature.com/articles/s41550-021-01371-7
[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2YK4cQbpKBuEad@4YmqjbhAAAAI4&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
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[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33YK4cQbpKBuEad@4YmqjbhAAAAI4&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[5] https://global.jaxa.jp/press/2021/05/20210525-1_e.html
[6] https://regmedia.co.uk/2021/05/26/asteroid_ryugu_jaxa.jpg
[7] https://www.theregister.com/2021/04/21/japan_accuses_china_of_attacking_jaxa/
[8] https://www.theregister.com/2020/12/07/hayabusa2_sample_return_success/
[9] https://www.theregister.com/2020/07/14/hayabusa2_sample_return_december_6_2020/
[10] https://www.theregister.com/2020/03/26/hayabusa2_small_carry_on_impactor_study_findings/
[11] https://data.darts.isas.jaxa.jp/pub/hayabusa2/paper/Sakatani_2021/
[12] https://whitepapers.theregister.com/
So says a new [1]paper titled “Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body” published on May 24th in Nature Astronomy .
The paper is based on observations of the asteroid, not analysis of samples returned by Hayabusa2.
[2]
[3]
[4]
As [5]explained in a Japan Aerospace Exploration Agency (JAXA) summary of the paper, Hayabusa2 used its Thermal Infrared Camera and the infrared radiometer carried by its Mobile Asteroid Surface Scout (MASCOT) lander to get a look at Ryugu’s rocks.
They found that many of the rocks on Ryugu’s surface have low thermal inertia – a measure of how quickly they can be warmed or cool. Low thermal inertia indicates low density or high porosity.
[6]
Global map of Ryugu captured during descent
to Ryugu and used in this paper. Click to enlarge
JAXA’s summary of the paper describes images captured by the probe as depicting material “similar to a pumice stone used to remove dead skin cells on your foot.” By doing so it means, dear reader, that you have discovered something about asteroid rocks and astroboffins’ grooming habits of.
High porosity has also been observed in the core of comets, which are thought to be relics of the “planetesimals” – the balls of dust and rock that agglomerated and may eventually have grown into planets.
[7]Japan accuses Chinese military of cyber-attacks on its space agency
[8]Japan sticks the landing: Asteroid sample recovered from Hayabusa2 probe
[9]Japanese probe to land asteroid rock sample in Australia on December 6th
[10]BEHOLD! Japan's Hayabusa2 probe left human imprints on ASTEROID SAND
The paper’s many authors suggest that the stuff found on Ryugu are remnants of planetismals that never got big enough for gravity and pressure to squish their component parts into planets. They suggest that the porosity is intrinsic, and not the result of impacts with Ryugu or cracking, and that the asteroid therefore has a lot to teach us about how planets formed in our Solar System.
JAXA’s summary holds out some hope that the samples it holds will be found to contain material with the same porosity observed by other instruments.
Data used by the paper's authors is available [11]here , if you want the chance to draw your own conclusions. ®
Get our [12]Tech Resources
[1] https://www.nature.com/articles/s41550-021-01371-7
[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2YK4cQbpKBuEad@4YmqjbhAAAAI4&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
[3] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44YK4cQbpKBuEad@4YmqjbhAAAAI4&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offbeat/science&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=3&c=33YK4cQbpKBuEad@4YmqjbhAAAAI4&t=ct%3Dns%26unitnum%3D3%26raptor%3Deagle%26pos%3Dmid%26test%3D0
[5] https://global.jaxa.jp/press/2021/05/20210525-1_e.html
[6] https://regmedia.co.uk/2021/05/26/asteroid_ryugu_jaxa.jpg
[7] https://www.theregister.com/2021/04/21/japan_accuses_china_of_attacking_jaxa/
[8] https://www.theregister.com/2020/12/07/hayabusa2_sample_return_success/
[9] https://www.theregister.com/2020/07/14/hayabusa2_sample_return_december_6_2020/
[10] https://www.theregister.com/2020/03/26/hayabusa2_small_carry_on_impactor_study_findings/
[11] https://data.darts.isas.jaxa.jp/pub/hayabusa2/paper/Sakatani_2021/
[12] https://whitepapers.theregister.com/
Re: Pumice
UCAP
If the planetesimal formed outside of the ice line (i.e. far enough from the proto-Sun for the gases in the accretion disk to freeze) then the particles would probably have had gasses either embedded in them or covering them. If the planetesimal subsequently moved closer to the Sun, the ices would have sublimed back to gas, leaving the porous structure behind.
Big_Boomer
Could be dust particles accumulating due to static charge and eventually merging to form stronger bonds under localised micro-gravity, or could be solid matter that once contained various volatiles that sublimated leaving the solids behind. Sublimation tends to leave flow patterns behind though, so they need to be looking for those. Given the timescales involved I tend towards the static accumulation theory, but we do know that our planets have moved around quite a bit since their formation so no reason why asteroids wouldn't do the same, and that also backs up the sublimation theory.
Pumice
Is produced from mostly volvanoes that have low silica lava which is low viscosity but has a high percentage of gases dissolved in it.
The gases coming out of solution are what provides the pressure for the eruption in the first place.
I can't see how a similar mechanism would function on a low gravity planetisimal, shirley it would more likely be an agglomeration of particles loosely held together to account for the porousity?