Future Europa landers may be in danger of sinking into a surface less dense than freshly fallen snow:
Space scientists have every reason to be fascinated with Jupiter's moon Europa, and, in 2017, NASA and the European Space Agency (ESA) announced they are planning a joint mission to land there. As the video above explains, this little moon is thought to have a liquid ocean submerged beneath an icy crust. Scientists believe it could host extraterrestrial life. But Europa's surface is much more alien than any we've ever visited. With its extremely thin atmosphere, low gravity – and a surface temperature of some -350 degrees F. (–176 °C.) – Europa might not be kind to a landing spacecraft. The moon's surface might be unexpectedly hard. Or – as evidenced by a study from the Planetary Science Institute announced on January 24, 2018 – Europa's surface might be so porous that any craft trying to land would simply sink.
The study – published in the peer-reviewed journal Icarus – comes from scientist Robert Nelson. If you're a student of space history, its results might sound familiar. Nelson pointed out in his statement:
Of course, before the landing of the Luna 2 robotic spacecraft in 1959, there was concern that the moon might be covered in low density dust into which any future astronauts might sink.
Now Europa is the source of a similar scariness, with Nelson's study showing that Europa's surface could be as much as 95 percent porous.
Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations (DOI: 10.1016/j.icarus.2017.11.021) (DX)
(Score: 2) by looorg on Friday February 02 2018, @04:04PM (2 children)
Will they keep sinking and eventually come out on the other side or will we just have to build them with really long extendable legs? Can we just tie a really big balloon to the lander so it sort of just hovers over the surface and just doesn't really land?
(Score: 2) by maxwell demon on Friday February 02 2018, @04:57PM (1 child)
The nature of gravity together with the nature of friction will ensure that even if the complete moon is made of that porous material, they won't come out at the other side. Rather they will get to rest at the center of the moon. In that case, legs won't help, as there's no ground to stay on.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 3, Funny) by Immerman on Friday February 02 2018, @05:44PM
Oh ye of little faith - it'll be *surrounded* by ground, we just need to surround it with legs as well, and then it can stand just fine!