back to article BEHOLD! Japan's Hayabusa2 probe left human imprints on ASTEROID SAND

Astroboffins have analysed what happened when the Japanese probe Hayabusa2 shot a 2kg Small Carry-on Impactor (SCI) at asteroid Ryugu in 2019. Hayabusa2 unloaded the SCI with the intention of creating a crater we could study to figure out what asteroids are made of. The analysis of the SCI's impact, published in Science, …

  1. Chris G

    I hope they are careful with the samples from Ryugu, they could contain an alien virus that would threaten all human life on Earth.

    1. Annihilator

      Nothing that a healthy supply of bog rolls won't solve.

    2. oiseau


      Have you seen Daniel Espinosa's movie "Life"?

      Although a bit far fetched in many aspects, it left me wondering about just how much thought, peer review and control is actually going into the handling of whatever is brought back to Earth from space.

      For what we know, it could well end up being more than just asteriod sand.


      1. phuzz Silver badge

        Re: Threat

        Well, the wiki article on Planetary Protection should answer most of your questions in detail, but the short answer is lots of thought and peer review.

        Of course, it goes both ways. Scientists want to keep their samples contained so that there's no risk of them being contaminated by terrestrial stuff.

    3. jake Silver badge

      Careful doesn't even begin to describe it.

      But it's not because the boffins are worried about off-planet samples contaminating us, rather it's because they don't want garbage from our filthy planet on their nice, clean samples.

  2. Dunstan Vavasour

    Leaving our mark

    I'm reminded of the snail that crawled across the Cenotaph. When he got to the other side he looked back proudly at his snail trail and said "Look, I've left my mark".

    Yes, we're explorers, but our pride at putting our machinery in the beauty of space can seem misplaced.

    1. Tom 7 Silver badge

      Re: Leaving our mark

      ego = 1/knowledge.

      That mark was made to gain knowledge so it is very little to do with pride or the slime of ego.

  3. Neil Barnes Silver badge

    Thanks for the embiggenment

    Impressive to see just how long it takes (i.e. just how low the gravity is) for the ejecta to think about settling.

    @Dunstan V - I'm not convinced that the leaving of the mark was the primary cause, but merely a byproduct of a scientific measurement. If one takes the view that one should never make a mark anywhere, no matter how remote nor how 'unchanged', one would never get out of bed (and one's bed would not be in a house to keep the rain off).

    1. Anonymous Coward

      Re: Thanks for the embiggenment

      I thank all of the governments that still fund boffins so they can advance our knowledge by making marks.

      My marks are far less significant (unless you count Reg comments).

    2. Daedalus

      Re: Thanks for the embiggenment

      Given that the impact velocity was well north of the escape velocity of the asteroid, I doubt if any grains came back at all.

  4. Anonymous Coward
    Anonymous Coward


    Oh well. I was hoping to hear that they'd actually put little moulded human feet on the legs of a space probe, and landed it somewhere... :-)

    1. IceC0ld

      Re: Footprints?


      I was shooting for them parking Musk's Tesla on there :o)

  5. Martin Gregorie

    To see the full story, go here:

    This URL: points to a complete description of the experiment and several more illustrations. Its definitely worth reading.

  6. jake Silver badge

    Been there, done that.

    Sadly, though, when my Hayabusa shot out a Small Impactor it was about half a conrod (and bits of block) ... broke traction going into second at the track and way over-revved. Made a hell of a mess.

  7. Anonymous Coward
    Anonymous Coward

    Sand? Distant places?

    Did they see any deck chairs reserved with towels?

    1. Spherical Cow

      Re: Sand? Distant places?

      More importantly: wormsign?

  8. Spherical Cow

    That was a big hit!

    I'm impressed that a 5m rock was moved several metres, presumably by not much more than a blast of sand. I know the gravity is low but the impactor must still have packed a hell of a punch to do that.

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