Bob Pepin, Physicist Univ. of Minnesota

The following interview occurred on Feb. 3, 2006, between Bob Pepin and Jacinta Behne, Genesis education and public outreach team.

JB: Can you identify reasons why sample return missions offer benefits that other classes of missions can't?

BP: The prime reason is that sample returns come back to laboratories that are much more sophisticated than anything that can fly on a spacecraft. Facilities that we can use to attack these things in Earth-based laboratories are much more robust. NASA's Discovery Program has made them possible--a super concept.

There are some kinds of exploration where people will be necessary--standing on the surface of another object, and their equipment takes an experienced scientific eye to make them work. Apollo astronauts did a super job on the moon. We learned things that we otherwise wouldn't have known. Mars is a good case for robotics; eventually we'll need man there.

JB: NASA has indicated a strong favor of involving higher education - specifically targeting graduate students - in future mission Education and Public Outreach (E/PO) work. How do you respond to that?

BP: It's a great idea! This would be a great opportunity for highly motivated undergrads. Some of the best research work here is on the same par as with grad students. I'd like to see it including freshman and sophomores, carrying forward to grad school, and beyond.

JB: If given the opportunity to propose a new mission based upon gathering new science and developing new technologies, what would that be? Are there gaps that you can identify that you know are critical?

BP: It's easy and it's biased. I've been on the science team for years going to Venus. It's the one planet that we need to know much more about. It's tough, it's not easy to get to, and among the three terristrial planets, that's the one we're trying to get to. Venus.

JB: What was it about the Genesis mission that said to you, "I need to be a part of this!" ?

BP: What has been largely ignored and is so terribly important is a frontal attack on the composition of the sun. Burnett in his imagination came up with a challenging approach that had never been done before. What Genesis did was not an obvious target, yet, when you think about it, was so good. What do we know about the composition of the sun? We have spacecraft that measure certain elements--many of which are measured poorly on spacecraft. Then we have the moon, which came from heritage on Apollo missions with detectors of different chemical compositions. They get bashed and bent and are not a good way to collect. The idea of sending out ultra-pure materials to collect solar wind is something that I thought was brilliant! When Don [Burnett] asked if I'd like to be responsible for the second highest priority, I couldn't refuse.

JB: When you observed the hard landing on Sept. 8, 2004, what was your second reaction?

BP: I thought and knew a lot about the mission. When we saw the capsule buried, I knew that people won't understand this, but the science is still there. The solar wind is in these fragments. I wondered what happened to the gold foil. I found out later that it survived, which was pretty neat. The hard landing told the science team that we're not" finished" but things just got a lot more complicated. I tell the folks in Houston that the collectors-people will be analyzing pieces of those anyway.

JB: How would you characterize the mission's approach to sample retrieval and ultimate dissemination?

BP: The various announcements on progress for the next few months following return released as much information as possible. Don Burnett was telling the public what was needed in terms of science return. Mixed excitment, followed by a hiatus where the science team determines approach, followed by a big splash. Filling that gap can't happen to keep the public entertained. There will be silence for a while.

One of my staff members, Russ Palma, was giving a talk a month-all over the country! Generally university audiences, etc. He carried that message everywhere-face-to-face.

JB: How would you characterize the overall condition of the samples?

BP: They all originally looked like the beautiful mirrored sample, and what happened was that they broke. They got scratched, pitted, covered with Utah dust and scratched by flying dust. Sapphire fared better, broke into better pieces. For our experience, it doesn't matter about scratches or dust.

JB: Genesis hopes to verify that it has collected pieces of the solar nebula. Is that realistic?

BP: There are a couple of leaps between that. Current measurements are of the chemical composition of the sun. What we measure is not actually the sun, but we can arrange that.

The sun has 99% of what is in the solar system, and we think that chemically it hasn't changed much over the past 4.5 million years. We're looking at the young sun, as it is today. The other hope is through comets, and there are three ways that you can estimate this. The hypothesis for Genesis is that what we measure now is the composition at the beginning.

Another way is comets. They have to be one of the first things that formed in the solar system. dust and gases from surrounding nebula were included, without involving the sun at all.

The third way is even more interesting. We're after the composition of the starting material through the atmosphere of Jupiter. There is a huge atmosphere, and it's captured from the solar nebula, offering a pretty good sample of the starting material. Nitrogen. Is it like that of Jupiter?

JB: At what point did you join the team?

BP: Back in the very first proposal. it went head to head with Stardust. Genesis lost that round.

JB: Were you a part of the initial, pre-flight, collector identification team?

BP: Yes

JB: Tell me why your lab is focusing on gold collectors?

BP: We only do gold. We're after the volatile elements—things that are gases—noble gases, helium, neon, argon, and nitrogen. The first three can come from anythingsilicon, aluminum—so the reason that we just do gold is for nitrogen. We can amalgamate it. This is a reliable process. Gold has a wonderful property of wanting to get together with nitrogen, and amalgamates with mercury beautifully.

JB: When did you receive your first samples for analysis?

BP: March 2005 - gold kidney foil - had a lot of nitrogen in it.

JB: What was your first breakthrough?

BP: Amalgamation was going to work! Roger [Wiens, LANL] could artificially implant samples for us to test our process before we worked on flown samples.

JB: What is your most recent breakthrough?

BP: Low was gold foil was contaminated. Then we learned that the gold on sapphire was working beautifully.

JB: Can you describe your amalgamation process for me?

BP: The Mercury vapor amalgamates the gold sample and nitrogen releases in what might look like little particles oozing out of the gold. The process takes about three hours to run one gold sample.

JB: If today you were to characterize the chemical picture of your Genesis work for me, what would it look like?

BP: Gold on sapphire.

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