SETI bioastro: 4th Annual IAA Conference on Low-Cost Planetary Missions

From: Larry Klaes (lklaes@bbn.com)
Date: Tue Apr 25 2000 - 12:11:41 PDT


From: "Bruce Moomaw" <moomaw@jps.net>
To: "Europa Icepick Group" <europa@klx.com>
Subject: A new information treasure trove for us!
Date: Mon, 24 Apr 2000 03:16:40 -0700
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        I'd completely forgotten until tonight that the 4th Annual IAA
Conference on Low-Cost Planetary Missions was scheduled for May 3. Well, 92
pages of detailed abstracts are on line at

http://sd-www.jhuapl.edu/IAA/IAAabs.pdf

... and they're fascinating. They cover not only the designs of all kinds
of possible future Discovery-class missions all over the Solar System, but
also launch vehicles and techniques, miniature scientific instruments and
spacecraft designs, and a lot of abstracts on the Better-Faster-Cheaper
controversy.

        But particularly relevant to us are pg. 29-37, dealing with low-cost
future outer Solar System missions -- and specifically R. Gershman's
abstract (pg. 30-31) on JPL's apparently quite detailed preliminary designs
for the first Europa Lander. I quote the important passages:

        "A Europa Lander mission has been assigned high priority for the
post-2005 time frame in NASA Space Science Enterprise Strategic Plan. JPL
worked with the cognizant NASA science team to develop concepts capable of
satisfying the principal goals of such a mission and to identify long
lead-time technology elements...

        "The primary goals of the proposed mission are to characterize the
surface mterial from a recent outflow and look for evidence of pre-biotic
and possibly biotic chemistry. Secondary goals are to study the seismicity
of the Europan interior and to conduct other geophysical experiments to gain
information on Europa's internal structure.

        "The baseline mission concept described in the paper involves
landing a single spacecraft on the surface of Europa with the capability to
acquire samples of material from 1 meter below the surface, perform detailed
chemical analysis of the samples, and transmit the results directly to
Earth. A Delta-class launch vehicle is used for the direct transfer to
Jupiter, arriving after a flight time of roughly 2.5 years. A Ganymede
flyby as the spacecraft approaches Jupiter reduces the energy need for the
Jupiter orbit insertion and perijove raise maneuvers, which place the craft
in a 200-day orbit. There follows a series of satellite flybys augmented by
propulsive maneuvers to reduce the energy of the orbit until a 6-to-5 [orbit
period] resonance with Europa is achieved. The Europa orbit insertion burn
follows, with the craft ending up in a 100-km orbit around Europa, ready for
the descent burn to the surface. Because of the large delta V required (4
km/sec), the propulsion system comprises about 90% of the 1300 kg launch
mass.

        "The paper provides a detailed discussion of the benefits and
development status of the key spacecraft and instrument technologies needed
to accomplish the Europa Lander science objectives. The craft will require
novel, lightweight, radiation-tolerant components, particularly for the
propulsion system. It will also require new devices for acquiring,
distributing, and processing surface material, and it must be able to
perform a precision landing on Europa's surface. However, perhaps the most
critical new technologies are those necessary for the instruments which will
perform the desired scientific investigations. Particularly important are
isotopic/gas evolution/mass analysis instruments, and instruments for
elemental composition and mineralogy analysis.

        "Also described in the paper are some variations on the baseline
concept, including the addition of small auxiliary probes delivered to
different surface locations, and the addition of an experimental ice
penetration probe designed to reach and transmit science data from depths of
tens to hundreds of meters."

        So there you have it -- the probable portrait of the first Europa
lander mission. The one thing about it that surprised me was that
apparently the main spacecraft will soft-land on Europa, instead of just
dispatching smaller hard landers or penetrators from orbit around Europa or
Jupiter. Needless to say, I intend to get all the details on this (and I've
talked to Robert Gershman before).

         Page 36 also features a suggestion by Johns Hopkins student B.J.
Mitchell:

        "With no modification of the Europa Orbiter spacecraft, the
mission's scientific objectives could be extended after the endgame
encounter at Europa. This modification -- impacting the Orbiter on
Europa -- could result in greatly increased data from the radar sounder and
direct determination of the constitution of Europa's crust. It could also
provide data on the presence of organic material on Europa."

        That's all the details, but I presume Mitchell has in mind putting
the Orbiter into a final very low orbit around Europa (allowing much more
sensitive detection of echoes from the radar sounder), and then crashing it
and having Earth-based and orbiting telescopes try to observe the spectrum
of the impact plume, a la Lunar Prospector. I don't know if that last part
would work, but it's an intriguing idea.

        As I say, the whole Website is crammed with other interesting
abstracts (as just one example out of many, a detailed proposal for a
lightweight solar-powered Jupiter orbiter that would make repeated flybys of
Io to study it in detail). I urge you all to look at it. This appears to
be what we've been waiting for.

                                                                Bruce Moomaw

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