What to do if we discover life on Europa?

[Kryten]

Does it work from orbit with tens of km of ice? You would need to use a frequency at which water is reflective, but ice is very transparent, and high enough to get decent resolution, but below THz range (maximum frequency for current radar technology).

NASA already have a design for ice-penetrating radar, it's part of the reference Europa mission (Europa clipper). It might not end up on the actual probe because there are issues with transmitting the massive amounts of data produced at those distances.

[Idobox]

NASA already have a design for ice-penetrating radar, it's part of the reference Europa mission (Europa clipper). It might not end up on the actual probe because there are issues with transmitting the massive amounts of data produced at those distances.

Seriously? NASA has a ice-penetrating radar and they consider sending a probe to Europa without it? I can't think of a single experiment that would be more important for an orbital probe.

[Kryten]

Whether it goes depends on the architecture; orbiter or multi-flyby. The radar produces considerably more data than can be transmitted in real-time, and lifetime for an orbiter mission would be short (about a month) due to radiation issues, rendering it pretty much impossible to actually get a useful science return. The multi-flyby option results in less time at Europa, but means all the data can be downloaded in the downtime between passes.

[Aningaaq]

NASA already have a design for ice-penetrating radar, it's part of the reference Europa mission (Europa clipper). It might not end up on the actual probe because there are issues with transmitting the massive amounts of data produced at those distances.

I am very interested in your source if you could please supply it. I've read briefly about this radar but the specifications aren't too clear from what I've read. Radar weight and data file sizes could be reduced by using the radar on a lander/rover although that is not part of the Europa Clipper mission.

Seriously? NASA has a ice-penetrating radar and they consider sending a probe to Europa without it? I can't think of a single experiment that would be more important for an orbital probe.

Very important. There are alternatives such as infrared spectrometer and a mass spectrometer. However, this is not the same type of data but it is possible to get similar results. The data sizes might be considerably lower but an ice-penetrating radar can visually demonstrate geological characteristics unlike any other instrument.

Whether it goes depends on the architecture; orbiter or multi-flyby. The radar produces considerably more data than can be transmitted in real-time, and lifetime for an orbiter mission would be short (about a month) due to radiation issues, rendering it pretty much impossible to actually get a useful science return. The multi-flyby option results in less time at Europa, but means all the data can be downloaded in the downtime between passes.

The data file sizes depend on the transect lengths, depth penetration and resolution. They might be able to sacrifice a little bit of transect lengths and resolution for the sake of data retrieval. I imagine that a IPR designed for fly-by probes is a much heavier instrument than one used directly on the surface (see Yutu or other GPRs used on earth) too. a fly by IPR might not be the right instrument for this type of mission, but I guess we will see what they come up with!

For fun: I conducted a ground-penetrating radar survey this past summer. I collected a total of 4.5 kilometers of data for one area which resulted in 169 files that totaled at 220 Mb of data. The depth penetration was only about 3 meters. The file sizes to examine files much deeper would be massive. What are the limitations of data transmissions for a mission like the Europa Clipper?

[Idobox]

Whether it goes depends on the architecture; orbiter or multi-flyby. The radar produces considerably more data than can be transmitted in real-time, and lifetime for an orbiter mission would be short (about a month) due to radiation issues, rendering it pretty much impossible to actually get a useful science return. The multi-flyby option results in less time at Europa, but means all the data can be downloaded in the downtime between passes.

How much data are we talking about?

And what are you saying about radiation? In The Allen belt, you will mostly find electrons and protons, with some sulfur and oxygen ions. It can't be that hard to protect a probe against it.

[Kryten]

How much data are we talking about?

EDIT: Just to clarify, that's the total from 6 days of near-europa return for the flyby mission and 30 for the orbiter.

And what are you saying about radiation? In The Allen belt, you will mostly find electrons and protons, with some sulfur and oxygen ions. It can't be that hard to protect a probe against it.

It's roughly similar to the Van Allen belts, just thousands of times denser, and covering basically anything in the epicliptic.

Edited September 4, 2014 by Kryten

[Idobox]

Thanks for all the data.

I just checked the JUICE description, and they're using the same flyby strategy to solve the radiation problem, I didn't expect probes to be that sensitive to radiation.

By the way, JUICE should carry an ice penetrating radar with a vertical resolution of 30m, and a penetration depth of 9km. Let's hope Europa's ice sheet is thinner than that.

And does anyone know why ESA cares so much about Ganymede and Callisto when Europa is such a promising candidate for life? I can understand sending a Europa mission that does a little bit of science around the other moons, but not the other way around.

[Kryten]

By the way, JUICE should carry an ice penetrating radar with a vertical resolution of 30m, and a penetration depth of 9km. Let's hope Europa's ice sheet is thinner than that.

And does anyone know why ESA cares so much about Ganymede and Callisto when Europa is such a promising candidate for life? I can understand sending a Europa mission that does a little bit of science around the other moons, but not the other way around.

ESA has a lot more magnetospheric specialists than astrobiologists compared to NASA; to them, Ganymede (with it's own magnetosphere) is a tempting target. Callisto allows them to add another moon's worth of science return without having to face the more intense radiation of the inner parts of the system.