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Yay. Japan's Hayabusa2 has touchdown on asteroid Ryugu again and possibly collected more samples.
Japan's Hayabusa2 spacecraft has touched down on Ryugu for a second time, bagging samples which hopefully contain material from the subsurface of the asteroid.
[...]
The first touchdown in February saw Hayabusa2 successfully collect samples from the primitive C-type asteroid Ryugu, achieving one of the main science goals of the mission.

JAXA and ISAS however decided to proceed with a second touchdown in order to boost sample volume, perform an unprecedented multi-sampling from a planetary body and, crucially, collect subsurface material excavated by the SCI experiment. In doing so the team will aim to answer questions regarding the very low reflectance of Ryugu, give insight into the regional heterogeneity of celestial bodies and, through comparison, assess the impact of solar wind on the surface.
#Asteroids #Ryugu #Hayabusa2 #Japan #Space #Exploration
 
Yay. Japan's Hayabusa2 has touchdown on asteroid Ryugu again and possibly collected more samples.
Japan's Hayabusa2 spacecraft has touched down on Ryugu for a second time, bagging samples which hopefully contain material from the subsurface of the asteroid.
[...]
The first touchdown in February saw Hayabusa2 successfully collect samples from the primitive C-type asteroid Ryugu, achieving one of the main science goals of the mission.

JAXA and ISAS however decided to proceed with a second touchdown in order to boost sample volume, perform an unprecedented multi-sampling from a planetary body and, crucially, collect subsurface material excavated by the SCI experiment. In doing so the team will aim to answer questions regarding the very low reflectance of Ryugu, give insight into the regional heterogeneity of celestial bodies and, through comparison, assess the impact of solar wind on the surface.
#Asteroids #Ryugu #Hayabusa2 #Japan #Space #Exploration
 
YORP effect apparently has made this asteroid spin so fast, it's breaking up.

"[S]unlight [i.e., the YORP effect] can spin up an asteroid, making it rotate faster. That's no big deal in the short term, but in the long run it spells disaster: At some point the rock is spinning so rapidly that the centrifugal force outward on its surface balances the gravitational force inward. If you're a rock sitting on the surface, over time as the asteroid spins faster you feel less and less gravity. You weigh less!
[...]
Is this what's happening to Gault? Observations from the ground indicate it has a rotation rate of about 2 hours, and it turns out that's almost exactly where you expect the rotational speed to start causing effects like this! Also, the dust is leaving the asteroid relatively slowly, at speeds of under a meter per second (less than walking speed). That's also about what you'd expect from dust launched into space by a landside (and the rotational speed of the asteroid on the surface near the equator is about 2 meters per second, which also gives the dust a kick).
[...]
It all adds up: Gault has been getting spun up by the ethereal breeze of light from the Sun, and is now very close to the point where it'll fly itself apart."

#Science #Space #Astronomy #Asteroids #Dynamics #YorpEffect
 
YORP effect apparently has made this asteroid spin so fast, it's breaking up.

"[S]unlight [i.e., the YORP effect] can spin up an asteroid, making it rotate faster. That's no big deal in the short term, but in the long run it spells disaster: At some point the rock is spinning so rapidly that the centrifugal force outward on its surface balances the gravitational force inward. If you're a rock sitting on the surface, over time as the asteroid spins faster you feel less and less gravity. You weigh less!
[...]
Is this what's happening to Gault? Observations from the ground indicate it has a rotation rate of about 2 hours, and it turns out that's almost exactly where you expect the rotational speed to start causing effects like this! Also, the dust is leaving the asteroid relatively slowly, at speeds of under a meter per second (less than walking speed). That's also about what you'd expect from dust launched into space by a landside (and the rotational speed of the asteroid on the surface near the equator is about 2 meters per second, which also gives the dust a kick).
[...]
It all adds up: Gault has been getting spun up by the ethereal breeze of light from the Sun, and is now very close to the point where it'll fly itself apart."

#Science #Space #Astronomy #Asteroids #Dynamics #YorpEffect
 
The highest resolution image of MU69 taken by New Horizons is now available. Phil Plait explains what it shows and what it can tell us about the population of bodies out there.
After the monumentally successful flyby of Pluto in 2015, the New Horizons spacecraft continued on into the outer solar system. After traveling at more than a dozen kilometers per second out an additional billion kilometers or so, it shot past the odd little rocky iceball 2014 MU69 on January 1, 2019, passing it by the razor-thin margin of just 3,500 kilometers … and that was after traveling for over 6.6 billion kilometers from Earth!

New Horizons took a lot of data during this encounter, comparable to what it did at Pluto, and it'll be another year or more before it's all back on Earth. So the New Horizons team did a clever thing: They prioritized what images to send back first. Among the highest priorities was getting the highest-resolution image sent back from the closest encounter as quickly as possible.

And now that image is here.
[...]
You might think that being out there, exposed to space out past Neptune for billions of years, MU69 would be covered in craters. For Pluto that's not the case because we think its surface gets repaved, so to speak, from subsurface processes that bubble up liquid from the interior. However, MU69 is far too small for that, and is certainly solid throughout. So a dearth of craters means there must be a dearth of impactors.

Interestingly, some scientists actually predicted this! They used the number of small craters seen on Pluto and its huge moon Charon, together with measurements and estimates of sizes of small objects past Neptune (called trans-Neptunian objects [TNOs], or more specifically in this case the Kuiper Belt), first to try to figure out the size distribution of objects out there capable of hitting MU69, and then to predict the size distribution of craters on MU69. Keep in mind that this was all done before the MU69 encounter!
#Space #Astronomy #Asteroids #NewHorizons #MU69 #UltimaThule #Exploration
 
The highest resolution image of MU69 taken by New Horizons is now available. Phil Plait explains what it shows and what it can tell us about the population of bodies out there.
After the monumentally successful flyby of Pluto in 2015, the New Horizons spacecraft continued on into the outer solar system. After traveling at more than a dozen kilometers per second out an additional billion kilometers or so, it shot past the odd little rocky iceball 2014 MU69 on January 1, 2019, passing it by the razor-thin margin of just 3,500 kilometers … and that was after traveling for over 6.6 billion kilometers from Earth!

New Horizons took a lot of data during this encounter, comparable to what it did at Pluto, and it'll be another year or more before it's all back on Earth. So the New Horizons team did a clever thing: They prioritized what images to send back first. Among the highest priorities was getting the highest-resolution image sent back from the closest encounter as quickly as possible.

And now that image is here.
[...]
You might think that being out there, exposed to space out past Neptune for billions of years, MU69 would be covered in craters. For Pluto that's not the case because we think its surface gets repaved, so to speak, from subsurface processes that bubble up liquid from the interior. However, MU69 is far too small for that, and is certainly solid throughout. So a dearth of craters means there must be a dearth of impactors.

Interestingly, some scientists actually predicted this! They used the number of small craters seen on Pluto and its huge moon Charon, together with measurements and estimates of sizes of small objects past Neptune (called trans-Neptunian objects [TNOs], or more specifically in this case the Kuiper Belt), first to try to figure out the size distribution of objects out there capable of hitting MU69, and then to predict the size distribution of craters on MU69. Keep in mind that this was all done before the MU69 encounter!
#Space #Astronomy #Asteroids #NewHorizons #MU69 #UltimaThule #Exploration
 
Japan's Hayabusa2 spacecraft to attempt to do sample collection from Ryugu.
More than 4 years after launch and a half year surveying asteroid Ryugu in space, Japan's Hayabusa2 spacecraft is ready for its biggest moment yet: sample collection. The spacecraft is scheduled to touch down on Ryugu at 08:15 Japan time on 22 February (21 February 23:15 UTC, 18:15 EST). If all goes well, Hayabusa2 will gently touch Ryugu with its meter-long sample horn, fire a bullet made of tantalum into the surface, and capture the resulting cloud of dust and debris.
#Space #Exploration #Asteroids #SampleCollection #Japan #Hayabusa2 #AsteroidRyugu
 
Japan's Hayabusa2 spacecraft to attempt to do sample collection from Ryugu.
More than 4 years after launch and a half year surveying asteroid Ryugu in space, Japan's Hayabusa2 spacecraft is ready for its biggest moment yet: sample collection. The spacecraft is scheduled to touch down on Ryugu at 08:15 Japan time on 22 February (21 February 23:15 UTC, 18:15 EST). If all goes well, Hayabusa2 will gently touch Ryugu with its meter-long sample horn, fire a bullet made of tantalum into the surface, and capture the resulting cloud of dust and debris.
#Space #Exploration #Asteroids #SampleCollection #Japan #Hayabusa2 #AsteroidRyugu
 
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