NASA's Dawn spacecraft turned science fiction into science fact by using ion propulsion to explore the two largest bodies in the main asteroid belt, Vesta and Ceres. The mission will end in fall 2018, when the spacecraft runs out of hydrazine, which keeps it oriented and in communication with Earth.



[Marc Rayman] You know, when you work on a mission this long it feels like a part of you.

I've been a space enthusiast since I was four years old.

Getting to work on a mission like this's a dream come true.

To me, Dawn is truly Earth's first interplanetary spaceship. No other spacecraft has gone to a distant body, gone into orbit around it, maneuvered there, then broken out of orbit, traveled elsewhere in the solar system to another alien world and going into orbit around it. And it does that with ion propulsion which I first heard of on a Star Trek episode. We've turned ion propulsion from science fiction into science fact.

[Carol Raymond] The Dawn mission really is a journey back to the beginning of the solar system. That's why we call it Dawn. We chose two time capsules from the beginning of the solar system, Vesta and Ceres, which are the most massive and largest bodies in the main asteroid belt. They both formed very early when the solar system was forming out of the protoplanetary disk and yet they ended up in these two very different states.

Vesta is a dry, rocky body that looks a lot like our moon. Whereas Ceres had a lot of water and it looks much more like the icy moons of the outer solar system.

[Rayman] And it seems like what determined their eventual fate was the location where they started. And we now believe that Ceres formed much farther from the sun than it is now.

[Raymond] When Dawn found the bright material on Ceres, what we saw was completely mind blowing. It was made of sodium carbonate. Sodium carbonate is not common in the solar system but we see it coming out of the plumes of Enceladus, we see it in lakes on Earth, and here it was on the surface of Ceres.

[Rayman] The mission will end when Dawn runs out of the conventional chemical propellant that it uses to orient itself in the zero gravity of space. Dawn will become this inert celestial monument in orbit around the dwarf planet that it unveiled.

Dawn serves a lasting reminder that the passion for bold adventures and our noble aspirations to reach out into the cosmos take us far far beyond the confines of our humble home here on planet Earth.

[Text] The Dawn spacecraft has operated for 11 years, three years longer than originally planned.

[Text] When its hydrazine fuel runs out in late 2018, the spacecraft will no longer communicate with Earth.

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