Dawn: NASA's Mission to the Asteroids



This comes under the heading of: “I really should have known more about this.”

In September, Dawn will launch toward the asteroid belt. Running on an ion engine, it will have the ability to maneuver into orbit around Vesta, stay there for over a year, then blast off to Ceres and place itself into orbit there.

There are several reasons to love this mission. First of all, the target. I’ve always been interested in the asteroids. It seems to me that while landing on Mars may well be psychologically important, there probably isn’t anything there worth going to. Getting in and out of that gravity well completely defeats the purpose of doing anything useful (as opposed to pure scientific work).

The asteroids, on the other hand, have a negligible gravity well. It is easy to approach them, do your business, than leave again. No atmosphere, no heavy braking, no need to carry or create propellants to lift off again. If you are looking for an economical way of exploring and exploiting our solar system, the place to start is the asteroids.

Vesta is the second largest asteroid, with a diameter of 330 miles – Ceres is the largest at 570 miles. Both are made of different stuff. Indeed, the material making up Vesta is so unique it has been possible to trace meteorites on Earth to it.

The second reason to love the mission is the whole concept of an ion drive. Dawn shoots out a very small stream of particles accelerated to a fantastic speed to keep a constant, very small level of propulsion. With an extremely high specific impulse, the ion engine essentially turns electricity directly into motive force. Perfect for a deep space rocket.

Back in 1992, when I was working in Moscow for Apple, we had the occasion (usually several times a week) to call for a gathering in one place or other. On a particularly cold and snowy night, one of us had located a new bar that actually made realistic margaritas located just outside of the Kropotkinskaya Metro Station – a truly unique pleasure at the time.

At the gathering were three of the four western Apple officers, a couple of Russian friends and colleagues, and a stranger who showed up a couple of times that winter. I don’t remember his name, but he was in his mid-twenties, a little pudgy, and a recent graduate from Tulane with a degree in space policy. He was NASA’s local Moscow rep.

After a couple of margaritas, my science-fiction-inspired youth couldn’t resist peppering him with question after question about what he was doing. After a couple of dozen questions, he finally said, “So let me tell you what I really do here. It’s not that interesting. The Soviet space program isn’t like NASA. There is no central governing body. There are, and were, lots of independent little groups, all doing one thing or another. Some of them are well integrated with the others, most of them aren’t.

“My job is to go through the files…” (physical files, since even the space program wasn’t really computerized) “…find things that are interesting and fax them to my bosses. Then they’ll look them over and say, ‘Yeah, no big deal.’ ‘We knew about that.’ ‘So what?’

“Just once I sent them something and they said, ‘They have a WHAT? Buy one, and send it over here.'” He didn’t tell us what that thing was he’d found. Even with all of the margaritas (I think he’d had three, and clearly wasn’t used to them), he kept quiet about that.

A couple of years after that, I started seeing reports of an ion drive that the Soviets had had since early in their program. Its discovery by the West, as documented here, clearly puts it in the same time sequence as our little party on a very, very cold Moscow night fifteen years ago.

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