> **GENESIS DISCOVERY MISSION -- STATUS AND LESSONS LEARNED.** D. S,
> Burnett, and the Genesis Project Team. California Institue of
> Technology (burnett@gps.caltech.edu).

**Introduction:** The Genesis Discovery Mission placed a spaccraft at
the L1 LaGrangian Point and exposed high purity materials to the solar
wind for 27 months. The collected samples of solar matter were returned
to Earth for isotopic and elemental analysis in terrestrial
laboratories.

Despite experiencing typical delays, the Aug. 2001 lauch and subsequent
mission were essentially nominal. The biggest in-flight issue was the
overheating of the Li-SO~2~ batteries which had a maximum termperature
requirement of 23^o^C, but by initiating a rigorous and realistic
testing program, in co-operation with LMA, we had great confidence in
the batteries even though the final temperature achieved was 60^o^ C.
This was a case where greater up-front effort to set a more realistic
technical requirement would have been highly cost-effective.

Despite great concern about the navigation risks in returning to UTTR,
and especially the Project's ability to evaluate of these risks, this
part of the misson was flawless. As is well known, re-entry however did
not go well. An incorrect g-switch installation prevented parachute
deployment, causing the crash of the re-entry capsule (SRC). There were
redundant g-switches, but in this case hardware redundancy did not
provide functional redundancy. Because of concern about collector
breakage if the SRC was parachuted to the ground, we were set up to do
helicaptor mid-air capture. There is no question in the mind of the
Project that this would have worked very well, but unfortunately we did
not get a chance to prove it. The cause of the Genesis re-entry failure
had nothing to do with using parachutes for sample mission SRC recovery
and this approach should 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 although
mangled, was essentially in one piece, and to recover a large number of
broken pieces of collector materials. Several high priority samples were
fortunately recovered intact (see below).

We expected to have 271 10 cm hexagonal collectors, 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 sapphire recovered, but
with only a few small pieces of Ge recovered, the rest being dust that
coats all the remaining fragments.

Having recovered all possible fragments, the major challenge to the
Science and Curation Teams is to deal with the particulate contamination
from the crash and the necessity to analyze smaller samples than
anticipated.

At present, the status of the science analysis phase of the mission is
that, despite serious challenges, we are not giving up on any of our
original science objectives, although we have been significantly slowed
down by the various contamination issues.

The rest of this abstract is devoted to a summary of science
accomplishments to date.

Beyond saving some material for posterity to analyze (a goal for all
sample return missions), the science objectives of Genesis are: (1)
measure the isotopic composition of solar matter, with O, N, and noble
gas analyses having the highest priority; (2) Provide greatly improved
solar elemental abundances (factor of 3 compared to those obtained from
solar spectral analyses): (3) Measure the compositon of
separately-collected samples of the three different kinds of solar wind
(regimes).

Genesis sample analysis proceeds on a broad front with 28 participating
laboraties around the world. A major advantage of sample return missions
is that redundant analyses are affordable, in many cases by different
techniques. Thus not only are data obtained but the accuracy of the data
can be independently verified. This is critical to a mission like
Genesis where everything we measure is quantitative.

The figure below shows the fortunate survival of

![](media/image1.pct){width="2.685416666666667in"
height="2.252083333333333in"}

of the only sample of "bulk metallic glass" (BMG) This material was used
becaused it could be etched uniformly to permit the depth distribution
of Ne to be measured. Lunar sample analysis had indicated that the
isotopic composition of Ne at energies beyond the solar wind was very
different. Surprisingly, the variations in Ne isotopic composition
observed in lunar samples were exactly reproduced by the BMG analyses at
the ETH, Zurich showing that the lunar variations could be explained by
implant isotopic fractionation, solving a long-standing lunar science
problem.

The figure below shows very precise Genesis data on the isotopic
composition of Ar from Washington U, St. Louis (this work) compared to
previous analyses.

![](media/image2.pct){width="2.602777777777778in" height="2.41875in"}

Lunar sample analyses had shown that the Earth and the Sun were
different, but different sets of data disagreed. The Genesis data
provide a precise measuremt of this difference which will tightly
constrain models of loss of the Earth's atmosphere early in its's
history. Similar Earth-Sun differences for Ne based on the Apollo SWC
experiment (U. Bern) are confirmed by Genesis.

The Genesis regime samples address the issue of possible isotopic
differences ("fractionation") between the Sun and the solar wind. The
different regimes were formed by different solar processes and, if
fractionations were important, these should vary among the regimes.
Analyses by Wash U and Zurich show that small fractionations do exist
for He (about 6%) but are not measureable for Ne or Ar. Our highest
science objectives are the isotopic compositions of O and N, and
although understanding of the He, Ne, Ar data is incomplete, the results
suggest that any differences between solar wind and solar isotopic
compositons for O and N will be small.

Very preliminary and relative imprecise data for the isotopic
composition of N are available from CNRS (Nancy, France) which give the
very surprising result that the solar N isotopic composition is close to
that of the Earth and very different from that for the atmosphere of
Jupiter. General expectations were that atmospheric loss had greatly
modified the Earth's N isotopic composition, but this appears not to be
true; moreover there are previously unrecognized major differences in
the isotopic compositions of at least one element between the inner and
outer solar system.

For elements, as opposed to isotopes, it was expected based on
spacecraft data, that elemental fractionations would be present between
the Sun and the solar wind. However, for elements with low first
ionization potentials (FIP\<9eV) the spacecraft data are consistent with
no fractionations between the Sun and the solar wind. Genesis data on
relative elemental abundances can test the hypothesis of unfractionated
low FIP elements with much higher precision.

A considerable effort has been made to measure the solar wind Fe/Mg
ratio. The great advantage of sample return missions in being able to
make replicate measurements, in this case on different collector
materials, 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 all available technology, solved the
problem and we now have a precise Fe/Mg ratio.

![](media/image3.pct){width="3.0805555555555557in"
height="1.773611111111111in"}

The above figure shows that the Genesis solar wind Fe/Mg ratio agrees
within the photospheric ratio (black) indicating that, within the errors
of the photospheric ratio, no fractionation of these two low FIP
elements has occurred and that at least for low FIP elements, improved
solar wind elemental abundances can be obtained. Similar comparisons can
be obtained from other elements and for the different regime samples
which should permit tight constraints on the possibility of elemetal
fractionation between the Sun and the solar wind.

In summary, although progress has been slow, significant accomplishments
have been made since the 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.