Thursday, November 18, 2010

Asteroids Up Close - Scientist Interview with Andrew Rivkin

Images: Scientists with returned sample, and illustration of sample collection.
The Japanese space agency (JAXA) has had great success with the return of a probe that visited asteroid Itokawa. This is the first time humans have returned a sample from an asteroid directly to the Earth. We have plenty of pieces of asteroids down here, of course - most meteorites are from asteroids. But we don't know which asteroid each meteorite came from. With the success of the Hyabusa mission, Japanese scientists are now holding small bits of rock from an asteroid, and they know exactly which asteroid they came from.

The idea of returning samples to Earth is a classic one in science fiction, as well as horror. I wanted to get a little more acquainted with the subject, and this mission specifically.  To that end, I thought I'd see if I could get an email interview from fellow planetary scientist, blogger, and asteroid expert Andrew Rivkin. Dr. Rivkin generously sent some well considered responses to my questions, and I'm happy to have the opportunity to present them here.

1. Please introduce yourself and tell us why one might consider you an asteroid expert.

I'm currently Senior Staff at the Johns Hopkins Applied Physics
Laboratory in Maryland working as a planetary astronomer. I've been interested in astronomy and the planets since I was a kid (I vividly remember Viking landing on Mars and the Voyager flybys) and interested in asteroids since I was an undergraduate at MIT. I did my dissertation work on infrared observations of asteroids and have been working in that field since, branching out to include concept studies of missions to asteroids and membership in a NASA committee to consider impact hazards.

2. What is your favorite Sci-Fi movie/book/event and why? Did popular science fiction have any influence on your choice of career?

Very difficult! I confess I never was much of a sci-fi reader growing
up, mostly sticking to Jules Verne and the Hitchhiker's Trilogy. Star Wars was absolutely huge for me, though, and I enjoyed the TV shows in its wake (the original Battlestar Galactica, Buck Rogers). I think I was already hooked on science by then, though. What may have had a big role, though not technically science fiction, were the speculative parts of Cosmos where Carl Sagan took us in the "starship of the imagination".

3. Give us the lowdown on the recent Hayabusa mission by JAXA, and what they discovered.

Hayabusa was a Japanese technology demonstration mission, it spent
time at the asteroid Itokawa taking images and other measurements before taking a sample of the surface and returning it to Earth for study--the first sample return for an object other than the Moon. The mission was exceedingly ambitious, particularly given its low price tag, and several times it looked like it would fail. However, some sample was successfully returned to Earth, and it was just announced that it's consistent with LL chondrite, a relatively common meteorite.

4. What makes this discovery particularly interesting or noteworthy?

There has been a longstanding issue in asteroid and meteorite science
with respect to how well we can determine compositions remotely and how much our analysis can be fooled. Exposure to micrometeorites and the space environment alters the lunar surface in ways we're only now beginning to understand, so this was potentially a test of how well we can apply what we know to bodies other than the Moon. Ten years ago I was a member of a team that gathered telescopic data for Itokawa and interpreted it as likely similar to LL chondrites, so we're happy to see we got it right!

5. Does this new information make it more likely that people will have greater faith in remote sensing techniques?

I sure hope so! :)

This is a great step in that process and critical for the asteroid
community. It's also interesting to note that there are other recent steps that emerged from the Mars program-- the Opportunity rover was targeted to land in an area based on orbital remote sensing, and Opportunity's measurements on the surface confirmed the remote sensing. Also, the identification of iron meteorite falls on Mars first came via the rover's remote sensing instruments, which were then confirmed by further analysis.

6. Thinking from a Sci-Fi perspective, what are the extremes to which this sort of mission or technique can be pushed. For example, can we become so certain of our remote sensing that we never have to visit anyplace anymore?

Interesting question. In some ways, this already has occurred. For
instance, since we can't go everywhere with a rover due to constraints of time (among other things), the rover operators already pick and choose which specific rocks and soils they want to do detailed sampling of by remote sensing-- something that looks uninteresting to the spectrometers (or perhaps "like everything else") is less likely to be visited. This was even true for the Apollo astronauts-- they were much more likely to sample unusual-looking material, trying to avoid sampling the same stuff over and over again by making judgments using their own remote sensing instruments: their eyes!

For the asteroids, we're still making our first forays into spacecraft
missions. But even here there are plenty of people who think we don't need to visit any more of one particular type of asteroid called the S class-- this is Itokawa's group as well as the group that a lot of other spacecraft targets belong to (Eros, Ida, Gaspra).

7. Is there any Sci-Fi that has an effect on your current thinking or attitudes as a scientist?

It is interesting to see the lines between science and science fiction
in some of the proposals and studies we see for coming years. The increasing computing power and capabilities of robotic spacecraft makes it possible to imagine a space program very different from the one we grew up imagining-- one where astronauts sit thousands of miles (or more?) away from the place they're exploring, using virtual reality and telerobotics to take advantage of those things that humans are best at while still maintaining safety (and indeed enabling stunts that might be ill-advised or impossible with an actual on-site astronaut). Something like a cross between Avatar and the Matrix, but without a pretense of "inhabiting" the remote explorer of the former, and without the evil computer part of the latter. :)

8. Anything else you'd like to add?

Carl Sagan called the 70s and 80s the golden age of space exploration,
where we encountered our solar system for the first time. With all due respect, I might suggest that that golden age continues today-- the discoveries made and data returned from Mars and the Saturn system every day are staggering but have become commonplace. We're finding other planetary systems and characterizing them. We've found worlds at the edge of our own solar system, and before too long we'll have our first look at Pluto. We're putting an orbiter around Mercury this coming year. As an asteroid scientist I must point out the great variety of missions we're enjoying, and I'm anticipating our first close look at Vesta next year and Ceres a few years following. And we're doing it as a species-- India, China, Japan, and Europe have all sent missions to the Moon or beyond (in some cases way beyond) in the past few years, and Russia is slated to send its first post-USSR mission within a few years. And this says nothing about human exploration, which is also an ongoing and international effort. It is a great time to be doing planetary science.

Many thanks to Dr. Rivkin for the interview!


Image Credit:  JAXA,


Amy said...

Wow! How cool that you were able to contact Dr. Rivkin and get his perspective on current discoveries in planetary science. I'm glad to hear he believes we are still in the "golden age" of discovery, and that we can do so much exploration right from our own beloved home planet.

Bryce Ellicott said...


I like to think we are still in the golden age, too. There are some amazing findings in the last decade, there there are no signs that it will let up anytime soon.