Deep Space 1, JPL’s successful mission to test 12 advanced
technologies in deep space to lower the cost and risk to future
science-driven missions that use them for the first time, comes to
an end Dec. 18.

Launched in October 1998, Deep Space 1 completed its primary
mission in September 1999. An extended mission to fly by Comet
Borrelly was achieved despite the loss of DS1’s star tracker-which
helps determine the spacecraft’s orientation-on Sept. 22, 2001,
providing researchers the best-resolution of the comet to date.

Project Manager Dr. Marc Rayman reflects on “the little spacecraft
that could” and the legacies it will leave.

Marc Rayman:

I remember when my grandfather died at an old age, a friend of mine
from China said, “Oh, you should be happy.” I immediately
understood: rather than being sad he died I was happy he had lived
so long. So I suppose I have the same feeling with Deep Space 1.
While there certainly are sad feelings saying goodbye to this
extension of ourselves, this event underscores what a wonderful
mission it was. I’m not sad it’s ending, I’m happy it accomplished
so much! And the mission ends on our terms, with a graceful and
planned termination after all objectives are complete.

I think we were able to accomplish so much because we had a small
but extraordinarily capable and dedicated team. And I wouldn’t
exclude the star tracker problem from that. Indeed, the recovery
from the loss of the star tracker was one of our finest
accomplishments. With a small team we had the agility to respond
quickly and efficiently. Our careful evaluation and acceptance (not
avoidance) of risk allowed us to have a very productive mission.

As I wrote in my most recent mission log (http://nmp/ds1/mrlog.html)
with respect to the comet encounter, “With a small team and a very
complex mission, too often we found ourselves having to choose which
problems we would penetrate. For the others, it generally became
necessary to go with our best estimate through a combination of
specific and limited technical information and a strong dose of
human judgment. But what if we had made a wrong choice in which
areas to focus our greatest attention, or what if the less well
considered decisions proved to be wrong in an important way? Well,
in that case, I wouldn’t be writing about the jubilation that
followed a truly flawless encounter.”

Indeed, the mission accomplished far more than I ever expected. I
did not even anticipate that we would be able to test all 12
technologies in the primary mission. That is a large payload, and it
required a tremendous amount of work to put them through their paces.

Many times I thought that if the mission ended then, we could all be
proud and happy with the results: Accomplishing NASA’s “minimum
mission success” criteria (defined before launch), accomplishing and
then surpassing the complete mission success criteria, recovering
from the loss of the star tracker, etc. At each stage, we kept going
and the team’s pride and sense of accomplishment only increased.

I think there are several legacies of Deep Space 1. Because of Deep
Space 1’s technology testing, many future missions that would have
been unaffordable or even impossible now are feasible. I think that
the results of the mission can contribute to a future with more
frequent, affordable, capable, and exciting space and Earth science
missions. Indeed, I’ve always maintained that the real science
return from Deep Space 1 is in the future missions that are enabled
by the technologies we tested.

Deep Space 1 took the risks to reduce the cost and risks of future
missions. Still, there is a more immediate scientific legacy from
the bonus comet encounter. We learned a great deal about comets with
the encounter, and the fantastically rich science data from Borrelly
will be the basis for much of the scientific work on comets for
years to come. In addition, there are now many comet missions in
flight or in development (Stardust, Contour, Deep Impact and
Rosetta) that will benefit from our experience.

I think the mission inspired many people who saw it as JPL and NASA
at our best-bold, exciting, resourceful and productive.