Saturday, July 16, 2011

Fiction comes to life, as Dawn approaches orbit around Vesta

Image Credit: Gregory J. Whiffen JPL

I'm not sure what is more impressive - the scientific feat, or the sense of humor with which it has been carried out.

This excellent (and funny) video outlines the development of the Dawn mission control center and the use of an Ion Drive in the mission, and where the Ion drives first ....ah... connects with our scientific cultural heritage. [Star Trek Movies]
The actual concept of ion propulsion was first put to paper in 1911 by Konstantin Tsiolkovsky with Harold Kaufman testing the first prototype drive in 1959 after decades of research. Ion Drives have been used in a number of recent missions including Deep Space 1 and Hayabusa.

Image Credit: NASA JPL Dawn Mission

Chief Engineer Marc Rayman like all good Trekkies keeps a "ship's log". On July 13th Dawn was about 23,000 kilometers (14,000 miles) from Vesta, and approaching it at 37 meters per second (83 mph). Dawn remains on course as it continues ion thrusting to reach its first science orbit this weekend.

The Dawn spacecraft, on its way to Vesta then Ceres, will be the first spacecraft to enter an orbit around a main belt asteroid, it carries a scientific payload, with four experiments.

- Framing camera for guidance
- Infrared and visual spectrometer
- Gamma ray and Neutron spectrometer
- Gravity science

Mission controllers are looking for return of the following data:

1) Images of Vesta and Ceres in three colors and black and white

2) Full surface with mapping spectrometer in three bands, 0.35 to 0.9 micron, 0.8 to 2.5 micron and 2.4 to 5.0 micron

3) Neutron and gamma ray spectra to produce maps of the surface elemental composition of each asteroid, including the abundance of major rock-forming elements (O, Mg, Al, Si, Ca, Ti, and Fe), trace elements (Gd and Sm), long-lived radioactive elements (K, Th, and U), and light elements such as H, C, and N, which are the major constituents of ices.

4) Radio tracking to determine mass, gravity field, principal axes, rotational axis and moments of inertia.

Scientists hope to learn about the makeup and composition of main belt asteroids, study their elements, identify any metals, trace elements and ice.

Recently main belt asteroid Scheila exhibited a brief cometary outburst (photos here) providing further possible evidence that some asteroids could carry significant amounts of ice.

The ten Kilogram GRaND - Gamma Ray and Neutron Spectrograph, perhaps the most complex of the instruments, will detect what radiates off the asteroid as it is hit by cosmic waves. The Mission "Splat Diagram" explains the different forms of radiation that are emitted and how this is captured by the instrument.

Based on the data the mission controllers hope to learn more about how the asteroids in the belt were formed.

Image: Data control interface for Ion Drive.

The data could also be also very useful, it we ever decide to paint an asteroid in an attempt to divert its path over a number of years. It would be good to know which color to use, and any additives. ;-)

Congratulations once again to the NASA JPL team.

UPDATE: July 16. Dawn has successfully entered orbit around Vesta.

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