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The First Europa Lander, What can be done first, cheapest & best?
nprev
post Dec 31 2005, 12:08 AM
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I think that many people in this forum would agree that somebody's going to have to land on Europa someday before the rather elaborate schemes to penetrate the outer ice layer will ever fly, if for no other reason than to get some relevant ground truth before committing to such an elaborate, expensive, and risky mission.

EO seems to have ruled out any surface science package for that mission (though it would be nice to change their minds! wink.gif ), but I think that there is a valid requirement at some point to directly assess the surface properties of Europa in an inexpensive yet creative way. Some candidate instrument payloads might be:

1. A sonar transducer/receiver set embedded within a penetrometer to determine crust density and examine the uniformity of the ice layer within the operational radius of the instrument (looking for cracks and holes, in other words).

2. A conductivity sensor again embedded inside a penetrometer to measure the native salinity of the surrounding material and possibly derive some constraints on the composition of metallic salts in the European crust (saltiness has a major effect on ice properties, in addition to the obvious need to derive the salt content of any underlying ocean).

3. A seismometer for all sorts of reasons.


How does this sound? Any critiques, additions, or subtractions? I omitted a surface imager not only because of bandwidth/extra complexity considerations but also because it seems desirable to penetrate the crust in order to minimize as much as possible reading any contaminants from Io during surface measurements. The orbiter data could be used to sense and subtract this from the penetrometer readings.


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PhilHorzempa
post Jun 27 2006, 04:07 AM
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It seems that at the November 2005 COMPLEX meeting there were
4 options presented for a Europa Lander that could be included as part
of the Europa Explorer mission.

Each of these options assumes the same plan for initial descent.
First, the lander arrives, eventually, with the Orbiter in a circular 100-km orbit
around Europa.
Second, after separation, the lander fires a thruster to
decrease velocity by 22 m/sec. This puts the lander into a 100 x 1.5 km orbit
around Europa.
Third, a large rocket burn takes place at periapsis to decrease velocity by 1,500 m/sec.
This essentially stops the lander cold and it begins to free-fall the last
1.5 km to the surface. This is the Stop and Drop maneuver. The remainig descent
to Europa's surface is where the designs diverge.

These are details of each of the 4 proposed lander designs.

1. JMI - Jovian Moon Impactor - This probe falls all the way to the
surface, impacting it at 62 m/sec. It is designed to withstand 5,000 - 10,000 g's and
looks to heritage from the Deep Space 2 Mars penetrators. This is where a precursor
mission like DS-2 has its payoff.
JMI Mass = 65 Kg

2. EPF - Europa PathFinder - After the Stop and Drop, EPF free falls to the surface, but
cushions its landing with 3 airbags, similar in size to the Beagle 2 design. The EPF itself
is desinged to withstand 600 g's and is saucer-shaped.
EPF Mass = 220 Kg

3. ESSP - Europa Surface Science Package - After the Stop and Drop, the ESSP utilizes
thrusters to slow its descent. The thusters cut-off at about 10 meters and ESSP freefalls
to semi-soft landing at about 40 g's or somewhat greater.
ESSP Mass = 350 Kg

Each of these first 3 landers is designed to have payload masses of about 7 - 8 Kg,
a lifetime of 3 days, power levels of about 10 W,
with a total science data transmission of 200-300 MBits.


4. IML - Icy Moon Lander - A true soft lander, using thrusters all the way to the surface
after Stop and Drop. Landing at less than 40 g's and using an RTG.
TMI Mass = 825 KG
The TMI is designed to last for 30 days, to have a power level of 100 W, to have a payload
mass of 40 Kg, and to transmit a total of 7 Gbit of data.

I think that the IML and/or the ESSP may use crushable materials to cushion the
landing on Europa. Also, these landers are able to be considered since the new
mission design for the Europa Explorer envisions using the Delta 4 Heavy as the launch
vehicle and the use of a VEEGA trajectory. The VEEGA trajectory design utilizes 1 Venus
and 2 Earth flybys and enables 7,000 Kg to be sent on the way to Jupiter.
This contrasts with the original Europa Orbiter design that contemplated
a payload of only 1,500 Kg to Jupiter.




Another Phil
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Guest_Richard Trigaux_*
post Jun 27 2006, 07:16 AM
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Why to limit the life time of a surface lander? if it has no RTG, it is understandable that the battery limits the lifetime (when it is exhausted). But a RTG has a theoretical lifetime of 30 years or more.

I know what the limiting factor is: radioactivity, which will quickly destroy any electronics. However there would be some strong interest into having a long lived probe on Europa surface:

-long run seismometre recording (a lone seismometre is not very useful, but a further mission may bring another one, so that they could work as a network and explore inner Europa structure, provided that the first is still working 10 or 20 years later).
-use it as a beacon or GPS emitter for a further mission or landing
-detecting underground SOUNDS on Europa, which may help to understand the oceanic properties.



So what I propose would be that the lander may have a pod, which would use the excess RTG heat to bury a small emitter/seismometre deep enough into the ice, so that it would be protected against radiations and could work for 20 or 30 years.

Could there be alternative power sources other than RTG?

-solar panels could still have some efficiency on Europe, but they would quickly degrade with radiations.

-a long wire left on the ground may gather enough electricity to feed a small circuit, with an emitter working in burst mode. On Earth, during magnetic storms, continuous currents can appear into power lines, strong enough to disturb their normal operation. On Europe, which moves into Jupiter magnetic field, a large copper loop laid on the ground may gather enough energy to feed a small aparatus, without all the hassle and problems of a RTG, insensitive to radiations, and for a virtually infinite time. A large capacitor battery would store the energy for emission bursts, of during magnetic storms (the current may be sometimes zero), without a limited lifetime like batteries.
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JRehling
post Jun 27 2006, 07:04 PM
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QUOTE (Richard Trigaux @ Jun 27 2006, 12:16 AM) *
Why to limit the life time of a surface lander?


Mainly with an eye towards the mass budget. There are time-varying phenomena on Europa, and there are non-time-varying phenomena (at least, on cycles of greater than 30 Earth days). Only a magnetometer and seismograph would be useful over long time scales; other than the diurnal changes in light and those two experiments, the only requirement for a long lifetime will be to grab samples near the craft... and that might be rather homogeneous itself. Some of the time variation the magnetometer will go looking for would repeat many times in 30 days anyway. So the question is how much mass is it worth (taking it away from surface composition instruments, or orbiter instruments) to get a long life out of a seismometer?
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nprev
post Jun 28 2006, 01:30 AM
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QUOTE (JRehling @ Jun 27 2006, 12:04 PM) *
Mainly with an eye towards the mass budget. There are time-varying phenomena on Europa, and there are non-time-varying phenomena (at least, on cycles of greater than 30 Earth days). Only a magnetometer and seismograph would be useful over long time scales; other than the diurnal changes in light and those two experiments, the only requirement for a long lifetime will be to grab samples near the craft... and that might be rather homogeneous itself. Some of the time variation the magnetometer will go looking for would repeat many times in 30 days anyway. So the question is how much mass is it worth (taking it away from surface composition instruments, or orbiter instruments) to get a long life out of a seismometer?


I would say that a long-lived seismometer would be worth quite a bit. Consider all the variables (potentially) involved: sub-shell oceanic tidal effects on the crust, undersea vulcanism, crustal structural failure events, resonance flexing from the other big moons...the seismic environment on Europa might be quite complex indeed, and thus would require long-term data acquisition.

Of course, you really need a lot more than one seismometer in one location to get a really useful dataset.


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Guest_Richard Trigaux_*
post Jun 28 2006, 07:42 AM
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QUOTE (nprev @ Jun 28 2006, 01:30 AM) *
...the seismic environment on Europa might be quite complex indeed...



and also very difficult to read, as whatever comes from the rocky core would have to pass through a liquid layer (eventually not continuous) and an ice layer (eventually not heterogenous). Worse, the water layer would play as a wave guide, bluring the origins of vibrations.

So with my opinium we should send a simple mission with one seismometre which would:

1) give an idea of rocky quakes (long term), to give an idea of how do do for a future cluster.

2) estimate the depth of ice and water layers. (a very useful step for a further lander/driller)

The best place on Earth to test the 2) would be on Ross ice shield, which is freely floating over water.

1) would work with a small lander,using a wire loop to sustain a long-term activity.

2) would be a one-shot, in the litteral meaning: a small shell impacts the surface at a (relatively) high speed, which produces seismic waves. Then it waits for the return from the ice bottom and ocean floor. Shortest mission than on Venus! This seems to be the simplest mission we can imagine, with yet an important result: the thickness of ice and water. Only hitch: it seems that most of Europa surface would rather be a layer of rubbles than plain ice. So this shell should aim at places where ther is plain ice, in the chaotic regions. This is a problem of a homing missile relying on a stored image of the target.
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Posts in this topic
- nprev   The First Europa Lander   Dec 31 2005, 12:08 AM
- - Steve G   QUOTE (nprev @ Dec 30 2005, 05:08 PM)I think ...   Dec 31 2005, 02:40 AM
- - BruceMoomaw   JPL's study of useful instruments for a small ...   Dec 31 2005, 03:33 AM
|- - JRehling   QUOTE (BruceMoomaw @ Dec 30 2005, 07:33 PM)St...   Dec 31 2005, 04:38 AM
|- - tty   QUOTE (BruceMoomaw @ Dec 31 2005, 05:33 AM)Th...   Jan 1 2006, 11:04 PM
- - edstrick   as Bruce points out.. hit the surface slightly off...   Dec 31 2005, 12:17 PM
|- - Bob Shaw   There are *natural* penetrators as well as man-mad...   Dec 31 2005, 12:40 PM
- - gpurcell   I think it is going to be pretty difficult to argu...   Jan 1 2006, 05:01 PM
|- - nprev   Re the penetrometer descent alignment problem: Wou...   Jan 1 2006, 09:11 PM
|- - RNeuhaus   QUOTE (gpurcell @ Jan 1 2006, 12:01 PM)I thin...   Jan 5 2006, 05:06 PM
- - BruceMoomaw   Uh-uh. An object that short would take weeks -- a...   Jan 1 2006, 09:42 PM
|- - nprev   Hmm. How about a "semi-hard" lander al a...   Jan 1 2006, 10:22 PM
- - ermar   QUOTE Europa has an atmosphere though it is extrem...   Jan 1 2006, 11:52 PM
- - tasp   Perhaps a future mission would drop an impactor at...   Jan 2 2006, 03:42 AM
|- - ljk4-1   QUOTE (tasp @ Jan 1 2006, 10:42 PM)Perhaps a ...   Jan 3 2006, 03:49 PM
- - tty   It's too bad there is no GPS system on Europa....   Jan 3 2006, 06:19 PM
|- - nprev   QUOTE (tty @ Jan 3 2006, 11:19 AM)It's to...   Jan 3 2006, 08:40 PM
- - nprev   AlexBlackwell posted the fact that the 2006 Discov...   Jan 3 2006, 11:59 PM
- - ljk4-1   Tell me this wouldn't be useful for an Europan...   Mar 29 2006, 07:47 PM
- - ljk4-1   Karl Hibbitts describes a proposed hyper-velocity ...   May 1 2006, 06:55 PM
- - PhilHorzempa   It seems that at the November 2005 COMPLEX meeting...   Jun 27 2006, 04:07 AM
|- - Richard Trigaux   Why to limit the life time of a surface lander? if...   Jun 27 2006, 07:16 AM
|- - JRehling   QUOTE (Richard Trigaux @ Jun 27 2006, 12...   Jun 27 2006, 07:04 PM
|- - nprev   QUOTE (JRehling @ Jun 27 2006, 12:04 PM) ...   Jun 28 2006, 01:30 AM
|- - Richard Trigaux   QUOTE (nprev @ Jun 28 2006, 01:30 AM) ......   Jun 28 2006, 07:42 AM
- - RNeuhaus   A panoramic camera plus an astronamic telescope to...   Jun 28 2006, 10:49 PM
|- - JRehling   QUOTE (RNeuhaus @ Jun 28 2006, 03:49 PM) ...   Jun 29 2006, 12:31 AM
|- - djellison   QUOTE (RNeuhaus @ Jun 28 2006, 11:49 PM) ...   Jun 29 2006, 07:23 AM
- - algorimancer   Considering the deliverable mass potential, and ou...   Jun 29 2006, 12:49 PM
- - djellison   I'm sure everyone would love a massive long li...   Jun 29 2006, 01:00 PM
|- - Stephen   QUOTE (djellison @ Jun 29 2006, 01:00 PM)...   Jul 3 2006, 11:20 AM
|- - Richard Trigaux   QUOTE (Stephen @ Jul 3 2006, 11:20 AM) Wo...   Jul 3 2006, 11:44 AM
- - Myran   Yes I agree with djellison and others. To give the...   Jun 29 2006, 03:36 PM
|- - JRehling   I don't think we can bet that a Europa rover w...   Jun 29 2006, 05:51 PM
|- - JRehling   QUOTE (Myran @ Jun 29 2006, 08:36 AM) The...   Jun 29 2006, 05:55 PM
- - RNeuhaus   Now I understand that it is very expensive to send...   Jun 29 2006, 08:14 PM
|- - djellison   QUOTE (RNeuhaus @ Jun 29 2006, 09:14 PM) ...   Jun 29 2006, 09:07 PM
|- - JRehling   QUOTE (RNeuhaus @ Jun 29 2006, 01:14 PM) ...   Jun 30 2006, 05:52 PM
|- - Bob Shaw   QUOTE (JRehling @ Jun 30 2006, 06:52 PM) ...   Jun 30 2006, 07:26 PM
|- - RNeuhaus   QUOTE (Bob Shaw @ Jun 30 2006, 02:26 PM) ...   Jul 1 2006, 02:45 AM
- - nprev   Harkening back to the origin of this thread, I com...   Jun 30 2006, 12:50 PM
- - algorimancer   My rationale behind sending a rover initially is t...   Jun 30 2006, 01:13 PM
|- - Bob Shaw   QUOTE (algorimancer @ Jun 30 2006, 02:13 ...   Jun 30 2006, 01:50 PM
- - djellison   Perhaps the cunning technique that would have been...   Jun 30 2006, 07:35 PM
|- - DDAVIS   QUOTE (djellison @ Jun 30 2006, 07:35 PM)...   Jul 1 2006, 01:16 AM
- - Richard Trigaux   There are three ways to protect electronics from r...   Jul 1 2006, 06:01 AM
|- - Bob Shaw   QUOTE (Richard Trigaux @ Jul 1 2006, 07:0...   Jul 1 2006, 01:55 PM
|- - mchan   QUOTE (Richard Trigaux @ Jun 30 2006, 11...   Jul 3 2006, 12:20 AM
|- - Richard Trigaux   QUOTE (mchan @ Jul 3 2006, 12:20 AM) Besi...   Jul 3 2006, 09:52 AM
- - edstrick   In the outer solar system, we have tended to find ...   Jul 1 2006, 08:50 AM
- - Myran   Just offhand and without checking I dont think any...   Jul 1 2006, 02:26 PM
- - djellison   Pushbroom? Doug   Jul 3 2006, 07:36 AM
- - nprev   Richard, that sounds good for a long-lived stand-a...   Jul 4 2006, 01:09 AM
- - Roly   March 26 2006 Powerpoint on various Europa Lander ...   Sep 3 2006, 07:07 AM
|- - angel1801   Has anyone thought of putting an Europa Lander at ...   Sep 3 2006, 04:27 PM
|- - ugordan   I would think the landing site will be determined ...   Sep 3 2006, 06:37 PM
|- - JRehling   QUOTE (angel1801 @ Sep 3 2006, 09:27 AM) ...   Sep 4 2006, 05:15 PM
- - Roly   Any chance that the launch vehicle for the Europa ...   Sep 4 2006, 03:01 AM
- - edstrick   The radiation is not FROM Jupiter. The radiation ...   Sep 4 2006, 11:07 AM
- - Julius   Being modest,I'd still say that 3 days lifetim...   Sep 5 2006, 08:03 PM
- - nprev   I still think a hard-lander, a penetrometer, or so...   Sep 6 2006, 01:43 AM
- - algorimancer   Something like the MER's autonomous navigation...   Sep 6 2006, 12:55 PM
|- - ugordan   Still, the biggest problem is soft landing via pow...   Sep 6 2006, 01:27 PM
- - algorimancer   I just had one of those Aha! moments and came ...   Sep 9 2006, 09:24 PM
- - Myran   Thats a wild idea algorimancer. But regardless ho...   Sep 10 2006, 07:42 AM
|- - algorimancer   QUOTE (Myran @ Sep 10 2006, 02:42 AM) Tha...   Sep 10 2006, 01:05 PM
- - nprev   Hmm. Given that the Galileo data was a bit limited...   Sep 10 2006, 09:00 PM
- - Drkskywxlt   I think any such impact with the surface of Europa...   Sep 11 2006, 01:32 PM
|- - AndyG   The (admittedly ill-fated) penetrators of Deep Spa...   Sep 11 2006, 03:34 PM
- - remcook   Most importantly IMO is the whole uncertainty of t...   Sep 11 2006, 04:12 PM
|- - algorimancer   QUOTE (remcook @ Sep 11 2006, 11:12 AM) ....   Sep 11 2006, 05:47 PM
- - Julius   Main objective should be to get a Europa lander sa...   Sep 12 2006, 07:37 PM
- - rasun   Hi! Apparently, NASA's Astrobiology, Scie...   Nov 29 2007, 05:35 PM
|- - JRehling   QUOTE (rasun @ Nov 29 2007, 09:35 AM) So ...   Nov 29 2007, 08:36 PM
|- - DDAVIS   This discussion is of particular interest to me as...   Dec 3 2007, 11:17 AM
|- - JRehling   QUOTE (DDAVIS @ Dec 3 2007, 03:17 AM) Thi...   Dec 3 2007, 07:05 PM
- - nprev   Wow. Don, only thing I can think of is that th...   Dec 3 2007, 12:46 PM
- - dvandorn   I would say that not only is it imperative that a ...   Dec 4 2007, 07:54 AM
|- - JRehling   QUOTE (dvandorn @ Dec 3 2007, 11:54 PM) T...   Dec 4 2007, 03:02 PM
|- - hendric   QUOTE (JRehling @ Dec 4 2007, 09:02 AM) U...   Dec 4 2007, 04:55 PM
- - nprev   Nihilistic, but IMHO painstakingly plausible, oDou...   Dec 4 2007, 12:19 PM
- - Cugel   Why would you go all the way down to the liquid wa...   Dec 4 2007, 01:06 PM
|- - JRehling   QUOTE (Cugel @ Dec 4 2007, 05:06 AM) Why ...   Dec 4 2007, 03:06 PM
|- - centsworth_II   QUOTE (JRehling @ Dec 4 2007, 10:06 AM) I...   Dec 4 2007, 03:55 PM
||- - marsbug   I dont know about squid but there are many studies...   Dec 4 2007, 04:35 PM
|- - Cugel   QUOTE (JRehling @ Dec 4 2007, 04:06 PM) I...   Dec 4 2007, 07:30 PM
||- - nprev   QUOTE (Cugel @ Dec 4 2007, 11:30 AM) At l...   Dec 5 2007, 01:45 AM
|- - tty   QUOTE (JRehling @ Dec 4 2007, 04:06 PM) I...   Dec 4 2007, 07:42 PM
- - centsworth_II   I think it's safe to say that the first Europa...   Dec 4 2007, 05:58 PM
- - dvandorn   I don't think I'd be good with just openin...   Dec 4 2007, 07:12 PM
- - charborob   A probe melting its way all through Europa's i...   Dec 4 2007, 08:03 PM
- - dvandorn   My thoughts exactly -- it's going to be a very...   Dec 4 2007, 08:58 PM
- - hendric   Well, RTGs actually put out quite a bit of heat, a...   Dec 5 2007, 01:41 AM
- - DDAVIS   Wow, this discussion is great! I am imaginin...   Dec 5 2007, 07:10 PM
- - tty   Let's do some order-of-magnitude calculations ...   Dec 5 2007, 07:23 PM
|- - hendric   QUOTE (tty @ Dec 5 2007, 01:23 PM) Let...   Dec 6 2007, 05:47 PM
- - mchan   QUOTE (dvandorn @ Dec 4 2007, 11:12 AM) A...   Dec 6 2007, 04:20 AM
- - nprev   Gotta say that I'm pretty sold on the pristin...   Dec 6 2007, 07:14 AM
- - edstrick   Both from a science and an engineering perspective...   Dec 6 2007, 09:39 AM
- - centsworth_II   At the least, a first Europa mission should map th...   Dec 6 2007, 05:02 PM
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