Then NASA Deputy Director of Planetary Division Jim Adams, center, and NASA Administrator Charles Bolden, right, review incoming data during the countdown to
launch of the twin GRAIL spacecraft in 2011 at the Cape Canaveral Air Force Station.
Credit: NASA/Bill Ingalls
RS: While working for NASA, you’ve been involved in
the development of several different systems to power
and to propel a spacecraft around the solar system.
What are some of your favorite technologies?
ADAMS: “The Dawn spacecraft uses an ion propulsion
that puts out a steady stream of xenon ions which
slowly changes the velocity of the spacecraft. It’s an
extremely efficient way of executing propulsion if you
have the system right. Because it is so mass efficient
we were able to actually send one spacecraft to two
different destinations in the asteroid belt. Dawn visited
Vesta in 2011 and is now on its way to arrive at Ceres
in 2016. If we were using conv entional propulsion –
chemical propulsion – we would not have been able
to launch a single satellite to both of those destinations.
Radioisotope power systems, those are the things
that have been used since the Voyager days that
take the heat generated from the radioactive decay
of plutonium 238 and make electricity. Then that
electricity is used to run the spacecraft. Voyager uses
one and that’s why we are still talking to Voyager today,
because it is still chugging away and making power
that allows us communicate with the spacecraft.
Two years before I joined the space program NASA
launched Voyager 1 and 2. They are a little bit older
than my career. An amazing factoid is that just now,
after 37 years of traveling to the outer reaches of our
solar system, they are reaching what some people call
the edge of the solar system. It is the edge of space
where the pressure from the gases released from our
Sun is roughly equivalent to the tenuous pressure of the
inter-stellar wind. But that point is just five percent of
the way to the outer reaches of the Sun’s gravity. The
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