Original URL: http://www.theregister.co.uk/2013/08/08/nasa_boffins_release_europa_mission_wish_list/

NASA boffins release Europa mission wish list

Dream lander design revealed

By Simon Sharwood

Posted in Science, 8th August 2013 06:27 GMT

PIC NASA boffins have revealed their wish list for a landing on Europa, the icy moon of Jupiter that looks a very promising candidate to host life and which was last April made a priority for future exploration by NASA.

Available here, the document says any visit to Europa should figure out if the moon's ocean is habitable, by measuring its icy crust, the composition of the liquid beneath and how Europan geology works.

Those objectives are important because “The habitability of Europa cannot be decoupled from processes associated with the evolution of its ocean and ice shell.”

The boffins have also designed an ideal payload of instruments for any future lander, outlined in the table below.

Model instrument Key scientific investigations and measurements
Mass spectrometer Surface and near-surface chemistry (especially organic content) to understand endogenic and exogenic processes and ocean composition.
Raman spectrometer Surface and near-surface chemistry (especially mineralogy) to understand endogenic and exogenic processes and ocean composition.
Magnetometer Ocean thickness and bulk salinity; depth to local water layers.
Multiband seismometer package Thickness of ice and local water layers; local ice-water heterogeneity; seismic activity and variation over tidal cycle.
Site imaging system Context of compositional measurements; material exchange processes; surface formation and evolution; landing site context.
Microscopic imager Context of compositional measurements; ice and non-ice grain characterization.
Reconnaissance imager Geological, regional, and local context of lander on the surface.

The paper also suggests any future lander packs a drill, albeit capable of reaching just ten centimetres into the ice.

Good news on the design front is that the projected instrument payload resembles that used by Curiosity and the Cassini probe, which should mean it's not terrifyingly hard to build. Bad news is that Europa's complex chemistry means a lander's instruments would need a “desired cleanliness level ... about an order of magnitude more stringent than that required” for the craft previously mentioned.

The issue of a landing site is also discussed. A location called “Thera Macula” is thought to be a site where Europa's complex internal workings are most visible and is therefore very attractive. Others wonder if an older, stabler, site doesn't offer a better chance to understand the moon's geology. Then there's the issue of radiation, which is often fierce thanks to Jupiter's presence. Mission planners will need to pick a spot where any lander can survive long enough to do useful science.

NASA's sketch of a future Europa lander

NASA's early vision of a Europa lander
Source: Europa Study Team, 2012.

The Juno probe, which will arrive at Jupiter in 2016, may therefore be asked to help with those considerations by focusing its attention on Europa. At present our best images of the moon are at between six and twelve metres-per-pixel, insufficient resolution to make a good guess about landing spots.

The paper doesn't get into niceties like how to get a lander to Europa, but does offer the illustration at right as an illustration of a craft that could get the job done.

No date for a Europa mission is floated, but with the moon on a list of three priority research targets, this paper does at least bring the possibility of a visit closer. ®