Transported to a different place
An alien asteroid could explain our place on Earth, writes Tom Whipple.
It felt, one of the scientists involved said, like being Christopher Columbus, discovering a new world. Some 300 million kilometres away, a lander touched down on a black and dusty rock. Then, having collected samples of an asteroid that could not be more different from Earth, it took off again.
The asteroid may be alien but the information gathered there could nevertheless explain our place on Earth.
Now, even before it has returned home, new images have been released from that landing a year ago, revealing tantalising information from a world that dates to the very start of the solar system.
Astronomers view asteroids as time capsules. ‘‘Asteroids are small enough to keep a memory of the original solar nebula from which the planets were formed,’’ said
ACROSS
Grey-faced (5) Insincere show of grief (9,5)
11 Apparel (5)
14 Bee product (5)
15 Stone coffin (11)
16 Abuse (8)
19 Cowboy film, book (7) 20 Way in (5)
21 Fastest team sport (3,6) 24 Orbiting device (9) 26 Baby's toy (6) 27 Courageous (6) 31 Hackneyed (5)
32 Paired (8)
34 Moon starer (anag)(10) 37 Towards the stern (3) 39 Gun barrel diameter (7) 40 Jolly (6)
41 Alleviation (6)
42 Male deer (4)
43 Artist's board (7) 46 Independently (10) 51 Declare one's approval of
(7) 1 4
Patrick Michel, from Universite Cote d’Azur in France, one of the scientists on the Japanese-led mission.
They are made of the same material from which the planets were formed but, unlike the planets, they have remained relatively untouched.
On a large planet geological processes heat and churn up the rocks. On an asteroid, eternally wandering in the vacuum of space, there is no such change. ‘‘They mean we can go back in time to trace the origins of the Earth.’’
This is why scientists think it is so important to understand their composition and, in particular, the nature of the organic molecules they contain – which could be a precursor to life.
But doing so in situ, as was the case with the European Space Agency’s recent Rosetta mission, is hard. A probe spacecraft will never have the instruments to analyse rocks to the extent researchers would like.
That is why Hayabusa2, the Japanese lander, was tasked with not only visiting an asteroid but also returning home. It is due to deliver its payload to Earth later this year. Until it does, the new images, described in the journal Science, are the best we have.
Dr Michel said the photographs were very nearly not taken at all.
The kilometre-wide asteroid was not as they had expected. ‘‘There were a lot of surprises. The abundance of boulders was extreme.’’
They had banked on there being a smooth landing area, but there was none. The team had to do some rapid recalibration to allow the craft to land with an accuracy of a few metres – rather than the planned-for tens of metres – slotting in between boulders.
The work was not helped by the surface itself.
‘‘It is super dark, darker than anything we have on Earth.’’
In one sense this is good. The darkness was likely from carbon and organic material – exciting stuff for an organism like us that is carbon based and runs on organic material. In another sense it was bad: the asteroid was so unreflective that the craft’s laser ranging instruments had almost nothing to reflect off.
Dr Michel said the scientists want to see if the organic material is ‘‘compatible with that of living things on Earth’’. Could ancient asteroids have seeded our planet with the precursors of life?
He added: ‘‘It’s something amazing, discovering a new world – and, wow, it’s fascinating.’’ Particularly now, he said, it was important for people to be able to see beyond lockdown, into a different place beyond this planet.
‘‘We have to make people dream.’’