Pushing the Envelope on the Solar System's 'Wild West' Frontiers
Strapped into his ejection seat at 15 different points, Dr. Alan Stern feels like a part of the powerful F/A-18 Hornet jet as it hurtles into the stratosphere. He's thrilled to be in the air and back on the hunt.
This isn't a combat mission. Stern is a planetary scientist. And while the U.S. Navy's F/A-18 Hornet is a battle-proven fighter jet, NASA's Dryden Flight Research Center converted this warbird into a powerful research tool.
Stern and his colleague, Dr. Daniel Durda, have been flying on the
modified F/A-18 Hornet with a sophisticated camera system called the
Southwest Ultraviolet Imaging System (SWUIS). They use the camera to search for a group of mountain-sized asteroids between the orbit of Mercury and our Sun that are so elusive and hard to see that scientists aren't even sure they exist. The camera has been used in the past on Space Shuttle missions and on other aircraft to observe comets, meteors and other asteroids.
The F/A-18 jet gives Stern one of his best shots at finding these giant space rocks, called 'Vulcanoids' after the Roman god of fire and metallurgy. The twilight is darker at high altitudes, which allows the camera to capture better images. He and Durda, who work at the Southwest Research Institute in Boulder, Colo., use the high altitude images to search for the Vulcanoids.
Even if he didn't get to hurtle into the stratosphere in the back seat of a high-performance jet, Stern would be finding other ways to explore what he calls the 'Wild West' of our solar system - mysterious, unexplored regions in space that may harbor clues to the origins of little neighborhood in the Milky Way galaxy. He loves his work.
For 22 years, Stern has focused on unexplored regions of our solar system. In addition to his work on Vulcanoids, he is the principal investigator on the proposed first-ever mission to Pluto and the Kuiper Belt - New Horizons. He has made detailed studies of Neptune's largest moon, Triton. Every now and then his desire to learn something new brings him closer to home to study asteroids or the atmosphere of our Moon.
But the most fun he's ever had - by any measure - is strapping himself into the backseat of that F/A-18 and soaring through the stratosphere on a Vulcanoids hunt.
We caught up with Dr. Stern between missions in his office in at the Southwest Research Institute in Boulder, Colo. He took a few minutes from his hectic schedule to talk:
What are Vulcanoids?
The Vulcanoids are a hypothetical population - an asteroid belt, if you will - inside the orbit of Mercury, which may or may not exist. It's very hard to determine whether or not it exists. We've been involved both in some modeling studies and in observations to actually try to detect some of them. As yet we have detected none.
How do you look for Vulcanoids in the backseat of a fighter jet?
These objects are inside Mercury's orbit and that means you can only hope to find them in visible light at twilight. And even then it's very tough. You could say, 'Well, I'll get rid of the twilight sky brightness by going into space,' but that's difficult in two respects. First, in a spacecraft you would fly through twilight literally in seconds, so there is very little time to collect the data. And secondly it would be very expensive.
However, you can conduct a very nice experiment by going to high altitudes where the air is thinner and the twilight is darker. And, of course, an aircraft is pennies on the dollar compared to a spacecraft. So for a lot less money - probably 10,000 times less money - we can do a much better experiment than you can do from the ground and in some ways a better experiment you can do in space, or at least from the Space Shuttle.
What kind of instrument do you use?
We have a very sensitive image intensified camera, which we have been using for years for low light level astronomy - on the shuttle in fact.
What's the flight like? It sounds like a lot of fun.
It's absolutely the most fun you can have on an observing run as far as I'm concerned. You get to fly a high performance supersonic aircraft on a routine basis. And we've been doing this for a number of years on other projects. Before the Vulcanoids, we were studying comet Hale Bopp in high performance jets. We've done asteroid occultation missions. We've done instrument development missions. We did the Leonid meteor shower. This has become absolutely a dream come true. We're doing frontline astronomy and we're doing it from a very sexy observing platform.
Not too many people get to ride in such a high performance aircraft.
The only two astronomers in the world that do this are myself and
Dan Durda. We fly with some of the best pilots in the world - test pilots from NASA Dryden. Of the seven pilots I've flown with over the years, two of them are ex-shuttle commanders. They are tremendously talented pilots.
What altitude do you go to do this?
We've flown missions as high as 60,000 feet. We've typically flown more like 50,000 or 45,000 feet. We're looking at ways of flying even higher up in the 70s.
Can you do that in an F-18 or would you need a different aircraft?
In a U-2 you can fly as high as 73,000 feet. In the F-18 there are zoom trajectories that will take you up very briefly into the 60s. We are pursuing both paths because we want to know if those Vulcanoids are there.
How did you get involved in this program? The typical picture of a scientist doesn't involve putting on G-suit and jumping in a jet?
I'll never tell! I'm kidding. I've had a long-term interest in aviation and I was a finalist to fly on the shuttle so I've been around hardware a lot. I've flown instruments for years. When the opportunity presented itself to go for comet Hale Bopp, we need a high altitude platform and we were able to show NASA that it was easier to turn the right astronomer into a backseater crewman than it was to turn a professional backseater into a guy who can do all the science.
My institute paid to send me to Pensacola Naval Air Station for the requisite training. And I took some other courses and of course the medical checks and came out the other end qualified to fly on the WB-57 and then later other aircraft.
So you could take the controls if you needed to?
This is not pilot training. It's aircraft systems, egress training, communications. It's really how to live aboard the aircraft and help the pilot as required. The backseater has a checklist to do. I won't pretend that I am landing the plane at night. I have got stick time on the airplanes and I've been flying airplanes for 20 years, but let's not pretend I am the pilot here. I am not.
How does it compare to some of the planes that you have flown? Is it a Ferrari compared to a Volkswagen?
It's even better than that.
Describe a typical mission.
They require a lot of preparation. We start about a month out. We flight plan it to the minute. We have very detailed instrument checklists. We do instrument rehearsals. Because I don't fly that often - a few times a year - almost every time I have to go through an ejection seat refresher course and a survival refresher. That's done out there. We install equipment in the airplane. There are several engineers and technicians involved and then we go through a pretty extensive alignment and test of the equipment before we fly. And then usually we have time off. We like to finish all the stuff early in case there are problems.
We get a little dinner - the missions are almost always in the dark. Almost every time we go out there [the Dryden Flight Research Facility in the Southern California desert] we have to have the flight suit, G-suit, the harness and all that checked again in case we have to get out of the airplane. We brief the pilot in detail to the way we want to conduct the mission. We suit up, go out to the airplane about an hour ahead of time, get on board and fire up the instrumentation. Then we strap in the ejection seat. It's not like putting on a lap belt to a car. For example, in the Hornet there are - you can count right down the list - fifteen separate connections you make the airplane that are either buckles that your legs or ankles or waist or chest or your shoulder harness or the oxygen of the G-suit or the communications, all that. And once we are part of the airplane, when the pilot's ready and the airplane's ready we close the canopy and we taxi and lift off.
It's a bubble canopy so the view is tremendous. It's night and the cockpit looks real high tech. And of course all you see out the front is the back of the ejection seat for the pilot and his helmet. And then you see the stars all around.
When you're going up, do you just kick the afterburners and go?
We don't need to do that. I've been on afterburner missions and we've flown supersonic runs as well. Usually, we try to keep turns under 2 Gs because we are flying this sensitive gear. We don't do aerobatics. We have a flight plan that is literally worked to the minute. The F-18 has a targeting computer for bombing runs that let us hit waypoints in space and time very accurately using GPS. We can throttle up if we're running a little late or if you're running fast you can either throttle back or do turns to extend. We hit usually between four and 12 waypoints on the flight where specific things have to happen - to either get into position, to calibrate the instrument or to take the data.
And then we come home, we land and we taxi and we get out of the airplane. Usually you're wringing wet because it's hot. We deintegrate the equipment off the airplane, get unsuited and go have a beer. It's usually midnight.
Now that you have the pictures, how will you spot a Vulcanoid?
We have an image of a given star field. We eliminate all the stars systematically. We know where they all are. We look for anything else that's there and we compare those images night to night to see if objects are moving. Now, the trick is you don't want to detect known asteroids, which are in the background. If you can picture in your head, we're looking off the limb of the Sun, but once you get beyond the Sun, your line of site goes all the way out to Oort Cloud so there are going to be asteroids in there. We don't want to announce the discovery of a Vulcanoid and have egg on our face if all we discovered was some asteroid we've known about for 100 years. So we also put on there by computer the position of all the asteroids that would be in that field to the faintness that we can detect.
We require that the object be moving at just the right rate and direction predicted by what a Vulcanoid orbit would be and that it not be one of the known stars or asteroids. So far we haven't found anything that's held up under scrutiny, but I have to tell you that we have only begun. We're not even near the limiting performance of this instrument.
What makes you think they are there?
I don't know if they are really there. What I can tell you from experience is that everywhere in the solar system, where there are stable orbital niches - the asteroid belt, the Kuiper Belt, the Trojan regions of Jupiter, you can go right down the list - every place there is a stable niche, material is there. So experience would tell us it's a fair bet that there may be some Vulcanoids. But we could be completely wrong. This is a different place. It's much hotter and so only certain materials could persist there. And because it's close to the Sun, radiation pressures can actually clean the region out. It is so much more affected than for example the asteroid belt; it may be that there are no Vulcanoids. I can't tell you until we finish, but I guarantee if we find them you won't have a hard time hearing about it.
How did you wind up working on the Pluto mission on the other end of the solar system as well?
I actually started my career in planetary science with a master's thesis on Pluto.
What's your title with the New Horizons Pluto mission?
I am the principal investigator.
Why do we need to send a spacecraft to Pluto and the Kuiper Belt?
We're in the space exploration business and the outer solar system is a wild, wooly place. We haven't explored it very well. Pluto and the Kuiper Belt have been just ranked by our once-every-ten-years decadal survey to be the highest priority for exploration in the solar system. That's not by our group, but an independent panel from the National Academy of Sciences. It's No. 1 on the runway for making progress toward understanding the birth of the solar system.
Why is that?
In part, it's because that region of the solar system is much more primitive. It's much more like the formation days. And also because we know so little, we have so much to gain.
Sort of like the way we learned so much in so few years from the Voyager missions?
Exactly. If you really want to learn more about this, I wrote a long article in Scientific American this year. It's called 'Mission to the Farthest Planet.'
It sounds like you love your job. Is there anything you don't like about your career?
No one working as an astronomer is shackled in chains. This is a tremendous profession. There are lots of neat people and you get to cool things. If I had to say something negative, it's that there's often a whole lot of travel that takes me away from my children. That can be a bummer a lot of times.
When did you know you wanted to be involved in space science?
I would say since I was 7 or 8. I've had this illness a long time.
What inspired you?
I just got real excited by the Apollo program and wanted to be part of space exploration.
How did you decide to focus on the planets of our solar system?
I like the planets because they are real places that you can go to and send machines to. Faraway astronomy - galactic astronomy and extra-galactic astronomy - is really cool stuff, but to me it's about destinations. I picked the outer solar system because by the time I was in graduate school all the first explorations of Mars and Venus and Jupiter, Saturn and Uranus were already out of the way and there was no chance to get on board something really groundbreaking. With Pluto and the Kuiper Belt, it's wide open. It's like the Wild West. You get to be the first to do things. It has its own romance and excitement in addition to the actual research value.
What kind of advice would you give to someone who wants to take the same career path as you?
Study hard. Whether it's atmospheric science, geology or engineering, whatever it might be - pick something that you really like to do because the hours are long. Go to the best school and hook up with the best people you can find. But also take some time out to be a well-rounded person.
Are there any people that inspired you?
John Young, Dave Scott and Harrison Schmidt, Apollo astronauts, all inspired me. If I had to pick people who really inspired me, it would be those guys and Carl Sagan.
What do you do for fun?
I raise my kids. I have three children. Between work and my kids, I pretty much gave up my other hobbies. I used to fly Cessnas, but I can't talk myself into it anymore. It's pretty hard to get into that Volkswagen once you've driven Mach 1 racers. I like gardening. I like photography. I've written some books and I like writing. But more than anything, I like raising my kids.
I also like my work. And there's way too much exploring to be done for a 40-hour week.
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