GENESIS DISCOVERY MISSION – STATUS AND LESSONS LEARNED. D. S, Burnett, and the Gene-
sis Project Team. California Institue of Technology (firstname.lastname@example.org).
Introduction: The Genesis Discovery Mission recovered, the rest being dust that coats all the remain-
placed a spaccraft at the L1 LaGrangian Point and ex- ing fragments.
posed high purity materials to the solar wind for 27 Having recovered all possible fragments, the major
months. The collected samples of solar matter were challenge to the Science and Curation Teams is to deal
returned to Earth for isotopic and elemental analysis in with the particulate contamination from the crash and
terrestrial laboratories. the necessity to analyze smaller samples than antic-
Despite experiencing typical delays, the Aug. 2001 ipated.
lauch and subsequent mission were essentially nomin- At present, the status of the science analysis phase
al. The biggest in-flight issue was the overheating of of the mission is that, despite serious challenges, we
the Li-SO2 batteries which had a maximum termpera- are not giving up on any of our original science objec-
ture requirement of 23oC, but by initiating a rigorous tives, although we have been significantly slowed down
and realistic testing program, in co-operation with by the various contamination issues.
LMA, we had great confidence in the batteries even The rest of this abstract is devoted to a summary of
though the final temperature achieved was 60o C. This science accomplishments to date.
was a case where greater up-front effort to set a more Beyond saving some material for posterity to ana-
realistic technical requirement would have been highly lyze (a goal for all sample return missions), the science
cost-effective. objectives of Genesis are: (1) measure the isotopic
Despite great concern about the navigation risks in composition of solar matter, with O, N, and noble gas
returning to UTTR, and especially the Project’s ability analyses having the highest priority; (2) Provide great-
to evaluate of these risks, this part of the misson was ly improved solar elemental abundances (factor of 3
flawless. As is well known, re-entry however did not compared to those obtained from solar spectral analys-
go well. An incorrect g-switch installation prevented es): (3) Measure the compositon of separately-
parachute deployment, causing the crash of the re-entry collected samples of the three different kinds of solar
capsule (SRC). There were redundant g-switches, but wind (regimes).
in this case hardware redundancy did not provide func- Genesis sample analysis proceeds on a broad front
tional redundancy. Because of concern about collector with 28 participating laboraties around the world. A
breakage if the SRC was parachuted to the ground, we major advantage of sample return missions is that re-
were set up to do helicaptor mid-air capture. There is dundant analyses are affordable, in many cases by dif-
no question in the mind of the Project that this would ferent techniques. Thus not only are data obtained but
have worked very well, but unfortunately we did not get the accuracy of the data can be independently verified.
a chance to prove it. The cause of the Genesis re-entry This is critical to a mission like Genesis where every-
failure had nothing to do with using parachutes for thing we measure is quantitative.
sample mission SRC recovery and this approach should The figure below shows the fortunate survival of
not be avoided because of the Genesis experience.
If a spacecraft is doomed to crash, the best planet
upon which to crash is the Earth. In our case, because
of excellent contingency planning by LMA and JSC,
we were promptly able to recover the SRC, which al-
though mangled, was essentially in one piece, and to
recover a large number of broken pieces of collector
materials. Several high priority samples were fortu-
nately recovered intact (see below).
We expected to have 271 10 cm hexagonal collec-
tors, but instead we now have over 15,000 pieces of
collector materials (greater than about 3 mm in size).
The losses varied greatly among the various collector
materials with many large (multi-cm) samples of sap-
phire recovered, but with only a few small pieces of Ge
of the only sample of “bulk metallic glass” (BMG) This result that the solar N isotopic composition is close to
material was used becaused it could be etched uniform- that of the Earth and very different from that for the
ly to permit the depth distribution of Ne to be meas- atmosphere of Jupiter. General expectations were that
ured. Lunar sample analysis had indicated that the atmospheric loss had greatly modified the Earth’s N
isotopic composition of Ne at energies beyond the solar isotopic composition, but this appears not to be true;
wind was very different. Surprisingly, the variations in moreover there are previously unrecognized major dif-
Ne isotopic composition observed in lunar samples ferences in the isotopic compositions of at least one
were exactly reproduced by the BMG analyses at the element between the inner and outer solar system.
ETH, Zurich showing that the lunar variations could be For elements, as opposed to isotopes, it was
explained by implant isotopic fractionation, solving a expected based on spacecraft data, that elemental frac-
long-standing lunar science problem. tionations would be present between the Sun and the
The figure below shows very precise Genesis data solar wind. However, for elements with low first ioni-
on the isotopic composition of Ar from Washington U, zation potentials (FIP<9eV) the spacecraft data are
St. Louis (this work) compared to previous analyses. consistent with no fractionations between the Sun and
the solar wind. Genesis data on relative elemental ab-
6 undances can test the hypothesis of unfractionated low
Lunar Reg. FIP elements with much higher precision.
A considerable effort has been made to meas-
Apollo foils ure the solar wind Fe/Mg ratio. The great advantage of
This work sample return missions in being able to make replicate
measurements, in this case on different collector mate-
air rials, revealed a problem in that different results were
obtained on two different materials. But another great
advantage of sample return missions, the ability to use
SOHO all available technology, solved the problem and we
now have a precise Fe/Mg ratio.
Lunar sample analyses had shown that the Earth and 1.0
the Sun were different, but different sets of data disa- 0.9
greed. The Genesis data provide a precise measuremt
of this difference which will tightly constrain models of Genesis
loss of the Earth’s atmosphere early in its’s history. 0.7 Photosphere
Similar Earth-Sun differences for Ne based on the 0.6
Apollo SWC experiment (U. Bern) are confirmed by
The Genesis regime samples address the issue 0.4
of possible isotopic differences (“fractionation”) be-
tween the Sun and the solar wind. The different re- The above figure shows that the Genesis solar wind
gimes were formed by different solar processes and, if Fe/Mg ratio agrees within the photospheric ratio
fractionations were important, these should vary among (black) indicating that, within the errors of the photos-
the regimes. Analyses by Wash U and Zurich show pheric ratio, no fractionation of these two low FIP ele-
that small fractionations do exist for He (about 6%) but ments has occurred and that at least for low FIP ele-
are not measureable for Ne or Ar. Our highest science ments, improved solar wind elemental abundances can
objectives are the isotopic compositions of O and N, be obtained. Similar comparisons can be obtained from
and although understanding of the He, Ne, Ar data is other elements and for the different regime samples
incomplete, the results suggest that any differences which should permit tight constraints on the possibility
between solar wind and solar isotopic compositons for of elemetal fractionation between the Sun and the solar
O and N will be small. wind.
Very preliminary and relative imprecise data In summary, although progress has been slow,
for the isotopic composition of N are available from significant accomplishments have been made since the
CNRS (Nancy, France) which give the very surprising Project literally hit bottom on Sept 8, 2004. With a bit
of luck, the major effect of the crash will be a delay in
when science measurement objectives are met.