[X] My Assistant

[jsheff]

Enceladus just jumped to way near the top of the list of biologically interesting places. We know how to get to Mars; we some ideas of further exploration of Euiropa and Titan. Has anyone designed a mission to land on Enceladus? What would it take? How much delta vee?

[vexgizmo]

James Oberg Chimes in:


Let Us Drink from the Fountains of Enceladus

[Guest_Richard Trigaux_*]

James Oberg Chimes in:
Let Us Drink from the Fountains of Enceladus

Jame's idea is a genius stroke: to use Stardust-like aerogel dust collectors to get samples of Enceladus plume, including eventual life chemistry and even life particules.

With this, no need of complex manoeuvers and landing, just some passes through the plume, as low as possible from the ground, and back to Earth with nearby intact samples.

At least, such a mission could be a preleminary for an actual landing, if it manages to take close images of the vents. Indeed a lander will need to know exactly where the vents are, and be able to squeeze in in order to get samples.


Oberg's idea looks like the easiest way to capture otherworldly biochemistry, and eventually life particules.

Enceladus water is not some ammonia eutectics, as expected on Titan (we are sure for this, there is no ammonia in the plume). It likely don't contain heavy sulphuric acid like expected on Europa (if so, it would not evaporate so easily).

Likely, most icy moons around Saturn have a comet-like composition, mainly ice and carbon materials. But they all melt at their formation (except the smallest like Hyperion and smaller) so that they differenciated between a white mantle of nearby pure ice and a black core of carbon materials. This core never melt, because carbon don't melt easily, and anyway it is soaked with water so that all the ice should evaporate before the core melts. (Phoebe would had had the same structure, but it was later stripped off its ice mantle). So, very likely, Enceladus core is a dust (not rock-hard) of carbon particules soaked with water (At times frozen, at times boiling, depending on the availability of gravitational flex heating).

So Enceladus core is very likely to contain an active pro-life chemistry, and eventually primitive forms of life. But we cannot expect too much: the early evolution of life heavily relies on the mobility of pro-cells and their hability to strive into great numbers into large spaces. A watertable is not so propicious! So what we may expect to find would be pro-cells, vesicles containing self-catalytic molecules (formed with amino acids and nucleic acids) but not DNA or RNA. But that only one of these vesicles is captured by an aerogel would tell us invaluable things on our own origins...

Hmm, if the surface is like a field of fresh-fallen snow, how about 'ski-braking'? Hand waving -- put something like pontoons on the spacecraft and a control system with radar and pressure-on-pontoon feedback to manage the force of contact with the surface. Drop it in with a surface grazing orbit. It would help to know there are no big rocks, ridges, or crevasses along the 'landing strip'.

There are blocks everywhere. Anyway, at a satellite speed, the contact even with a very soft material would be supersonic and result into an explosion.


Eventually if we find a planet made of aerogel, a probe could land on it head on, without any braking...

[ugordan]

<PESSIMISM>
IMHO, all this sudden talk about possible life on Enceladus is stretching the odds a bit too far. For all we know, liquid water (if it indeed exists in large quantities) could have persisted going back only a few tens of millions of years. Given the amount of time it took life to evolve on Earth, that kinda looks short, doesn't it?
Also, detection of fairly pure water as opposed to sulfuric acid on Europa doesn't IMHO go in favor of a suitable biosphere. Pure water just doesn't do it for life -- it's the organics and various other chemicals that do the trick. Granted, heavier organic species could still be detected lower in the plumes.
Enceladus is also a pretty small place, more likely to be in 'equilibrium' regarding energy or 'food' distribution so wouldn't that make any biologic metabolism hard to work?

All in all, to me Europa (even Titan's hypothetic subsurface ocean) is a far more likely candidate for life, even if it is much, much harder to explore. That said, Enceladus is still far more likely to harbor life now than Mars is -- at least here we have evidence of liquid instead of grasping at straws as on Mars.
</PESSIMISM>