Genesis : Search for Origins | JPL

The following interview occurred April 8, 2004 between Genesis Project Scientist Amy Jurewicz and Jacinta Behne, McREL.

J.B. You have a long history with the Genesis mission. Would you trace that history for us?

A.J. Actually, I was a relative late-comer to Genesis. I started work in the fall of 1998, when Genesis was already well into "phase C/D," the phase of the mission when the job of building the flight hardware is underway. Stepping into a mission as a project scientist that late is a bit like trying to drink out of a fire hose: there is an incredible amount of information that you need to know in order to do your job.

Project Scientist

Still, Don Burnett, the mission's principal investigator (PI), needed someone skilled in science who could also fabricate some of the Genesis materials at the Jet Propulsion Laboratory (JPL). Don and I have known each other professionally since my days of working at the Johnson Space Center in the early 1990's, and he thought that I was a great fit for the position. So I started with Genesis after my work on the Aerogel Team for the Stardust mission wound down.

I began working Genesis by overseeing the purchase, cleaning and coating of the sapphire-based collection materials. Later, I helped with one of the most exotic solar-wind collectors in the spacecraft: the 13C diamond in the concentrator. That collector was unique because it was fabricated from carbon of a single isotope (weight 13), whereas carbon in terrestrial diamonds has two stable isotopes, but carbon atoms of weight 12 predominate. The 13C (mass 13) carbon was used so that - when Genesis returned and the target was analyzed for oxygen - scientists wouldn't need to worry about distinguishing between 12C18O and 13C17O (molecules which both have weight 13+17=12+18=30) in the mass spectrometer when analyzing the material for oxygen isotopes. Anyway, diamond isn't electrically conductive, but all of the solar-wind collectors in the concentrator needed to be conductive. So, I fabricated a sputtering-target made of 13C (we actually needed to use a commercial multi-anvil press for that). Then the folks at Sandia National Laboratory then used the target to make an electrically-conductive coat for the 13C diamond in the concentrator.

Don Burnett and I also did diffusion studies to insure the viability of some of the collector materials we had selected. And I worked on the team that developed the lid-foil collector …. Working directly with the PI meant that I did a little bit of everything on the Genesis payload, as needed. It was an incredible experience.

J.B. Regarding the magnesium profiles, what does this new profile shown in the accompanying graphic tell us?

A.J.. That particular magnesium profile (Enlarge Image) was from a set of analyses done by Don Burnett as a demonstration. It shows that the solar wind has been captured in a piece of collector material, and that the amount of solar wind at increasing depth below the surface is consistent with the sum of solar-wind energies that the spacecraft encountered as measured by other onboard instruments. So, we can infer that the collector materials behaved as expected. While "behaved as expected" might not sound exciting, it really is. The profile says that the solar wind is there, we have caught it, and we can measure it. So, in essence, the profile means that Genesis science has officially started.

J.B. What are the acronym names that appear on the accompanying graphic?

A.J.There are five designations on the graphic that may need some explanation: 24Mg, GIM/GEM, #E41064c, SIMS and CZ silicon.

24Mg is the isotope of magnesium with weight 24, which is being measured. Let me explain further. The isotopes of an element are atoms that have the same atomic number but different atomic masses. If you look up the weight of magnesium on a periodic table, it is listed as having a mass of 24.31 units. That fraction doesn't mean that each atom has an extra 0.31 units of weight; rather, it means that 24.31 is an average number. In the case of magnesium, ~79% of the atoms have weight 24, but a measurable number of atoms with weights 25 and 26 are also present.

#E41064c, the name on the graphic, was given to that sample by the Johnson Space Center (JSC) curatorial staff. It uniquely identifies the fragment of Genesis collector that was analyzed, and there are photos available at JSC as a double check. That is one of the reasons that it was approximately 6 months before Genesis samples became available to the science community. All of the Genesis fragments - even now that there over 10000 of them - will be given identifiers and photographed before they are allocated to scientists, so that their history can be easily traced, even if they circulate among several laboratories.

GIM/GEM refers to the Genesis Ion Monitor and the Genesis Electron Monitor. These two instruments, provided by Los Alamos National Laboratory, continuously monitored the solar wind during the solar-wind collection period. The data that they returned was used to calculate solar-wind speeds and the solar-wind regime that was present each moment of collection.

SIMS refers to secondary ion mass spectroscopy, the method of analysis used to produce this data. I believe that there is a nice link to a program that demonstrates SIMS on the Genesis/JPL website.

CZ silicon refers to the type of silicon that the collector was made from. That is, the silicon in the collector was "Czochralski-grown." The Czochralski technique is a method were single crystals are grown by slowly pulling it from a silicon-metal melt. Silicon produced by this technique has different trace elements from silicon crystals fabricated using other methods.

J.B. How do you relate the graph to the picture in the upper right hand corner?

A.J. The fragment shown in the picture is the piece of collector that was analyzed. I should mention that the area that was consumed by the SIMS analysis was approximately 100 microns square (0.1mm by 0.1mm), so there is lots of area left for further analyses, even on this small fragment.

J.B. How much solar wind (or just magnesium) is this?

A.J. At this point, we are more interested in the shape of the profile - which indicates that everything is working properly - than in the absolute numbers. So the values shown in the graphic have not been precisely calibrated with respect to the number of magnesium atoms. However, before flight, we estimated that if the solar wind was concentrated in the top 1000 angstroms (half the depth of this analysis), the average concentration of solar wind 24Mg would be approximately 3.2 atoms per million atoms of collector, or approximately 0.0003 wt%. This equates to approximately 160,000,000 atoms of solar-wind 24Mg in the 0.1mm x 0.1mm area analyzed.

A.J. "Counts per second" refers to the number of atoms of mass 24 counted per second by the detector of the mass spectrometer. Not every Mg atom is counted, and not every signal at mass 24 is Mg; however, by analyzing a piece of silicon which we've implanted with 24Mg (a "standard", which we've already made) the counts per second can be accurately converted into the number of Mg atoms released per second of analysis.

J.B. How do you know that the data that is shown represents a sample that comes from the Sun?

A.J. What we know: (1) that there was no magnesium in these wafers before they flew; (2) that there is magnesium in them now that they've come back; and (3) that the depth at which the atoms are found in the wafer is, within error, what we have estimated from the solar-wind velocities that Genesis measured. So, we conclude that the magnesium that we've measured came from the sun.

A.J. Not yet: that wasn't the intent of this specific measurement. The fun stuff is yet to come.

J.B. When you aren't working on mission science, what fills your free time?

J.B. Is there any advice that you would offer to young women who are considering a career in space science?

A.J. When I was a kid, I watched the first men land on the moon. It was very, very exciting and, of course, I would have given anything to be an astronaut. But that option was unavailable to young women back then. I never really considered going into space science. My first job as a Ph.D. geologist was studying bubbles in glass for Owens Corning. Then I worked for the USAF doing research on some of their advanced ceramic -composite materials. Glass and ceramics are - in essence - only rocks, after all. In fact, I basically fell into Space Science after I followed my husband to Houston and found a job as a research-contractor at the NASA Johnson Space Center. But it felt very right; it was very exciting and I was thrilled to have the opportunity to do that work.

I should say that space science can be rewarding and lots of fun, but it is very demanding. There are easier ways to make a living. Before spacecraft launch, 50 hour weeks were typical, 70 hour work weeks were common, and I was always on call. So a supportive, understanding family is a must - and, believe me, it sure helps having a husband who cooks.

Read more interviews with Genesis team members that tell you about their lives, their jobs, and about the important role they play in the Genesis mission.