NASA scientists say that we are about to loose our favourite Dawn spacecraft that has been studying the Asteroid Belt largest objects Ceres and Vesta for the past 11 years. In the next few weeks Dawn will run out of fuel needed to keep the spacecraft’s antennas pointed to the Earths and instruments to the target. When it happens, Dawn will not be able to do any more science or talk to the ground control. It will continue silently orbiting the dwarf planet Ceres for quite some time, possibly for the next twenty years.

1. The last days of Dawn spacecraft

2. Why asteroids?
Ceres and Vesta are so very different form each other that
it is hard to believe they both reside in the same area,
called the Asteroid Belt, between the orbits of Mars and
Jupiter. Vesta is a planets-like rocky asteroid over 500
kilometers across. Ceres, which is about twice as big, is
an icy dwarf planet.
Asteroids are primitive bodies, space bricks, that in time
turned into planets and moons. They can tell us a story of
the Solar System formation and explain what kind of
conditions were there in its early years.

3. Mission timeline
2007, September 27 Launch
2009, February 18 Flyby of Mars (closest point)
2011, July 16 Entered orbit of Vesta
2012, September 04 Left orbit of Vesta
2015, March Entered orbit of Ceres

4. Our favourite Dawn spacecraft facts
•It’s got a fantastic engine
Dawn uses ion propulsion rather than chemical
propulsion. This technology was first tested on “Deep
Space 1” mission to the asteroid belt. But Dawn is the first
spacecraft to use ion drive not in a test, but in a real
mission. It allowed the spacecraft to get into one celestial
body’s orbit, maneuver, break free and move into the orbit
around another target. Ion propulsion is very effective. It
allows engineers to use less propellant and smaller launch
vehicles! Maybe ion propulsion will help humans reach
Mars one day!

5. •It is the only multiple-target mission to orbit both target bodies
The previous multiple-destination missions (like “New Horizons” mission to
Pluto and its future target Ultima Thule, “Voyager 1” to Jupiter, Saturn and
Titan, “Voyager 2” to Jupiter, Saturn, Uranus and Neptune) only flew past
their targets!
•It can take a really close look at the surface
Dawn is currently orbiting dwarf planet Ceres, its orbit takes the spacecraft
as close as 35 kilometers to the surface. That allows the spacecraft to use
one of its really cool instruments called gamma ray and neutron detector,
or GRaND, built by engineers from Los Alamos National Lab (Are you
thinking what I am thinking? Yep, Manhattan Project! )
This instrument detects particles that bounce off the asteroid’s surface
after it’s been hit by cosmic rays. By comparing the GRaND measurements
with the models (of how cosmic rays would have bounced off different
types of surfaces), scientists can figure out the dwarf’s surface
composition. Clever!

6. •It made lots of amazing discoveries and confirmed some or our
theories
…about Vesta
Dawn spacecraft studied Vesta’s surface features, especially its two
huge craters that formed long ago when Vesta collided with another
space object. The material ejected during the impact added more
rocks to the Asteroid Belt. It is also responsible for a certain type
of meteoroids found on Earth.
…about Ceres
Dawn’s pictures revealed surface deposits on Ceres, that turned out
to be epsom salts. The presence of these deposits indicates that in
the recent past there was a subsurface ocean that froze leaving the
salts exposed. Maybe the water is still there, under the ice? Organic
molecules were also found in a few places on the surface of Ceres.
But where these molecules came from and whether they have
anything to do with life remains unclear.
Planning a lesson about asteroids?
Feel free to use the Small bodies of the Solar System lesson plan
and other useful resources listed on our inflatable
planetarium website.