Computerized rendering of Dawn spacecraft and ion propulsion.

Distant mission to Ceres- dwarf planet

It’s what is known as a dwarf planet, just under 1000-kilometres in diameter orbiting out in the darkness of space out beyond Mars. It’s called Ceres.

“Dawn” is NASA’s probe to Ceres, on an archaeological mission of sorts.  It seeks to orbit the dwarf planet sending data back to Earth which will help scientists understand a little more about the origins of the solar system.

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As Dawn maneuvers into orbit, its trajectory takes it to the opposite side of Ceres from the sun, providing these crescent views. These pictures (part of the OpNav 5 activity), were taken on March 1 at a distance of 49,000 kilometers © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Paul Delaney (MSc) is Senior Lecturer of physics and astronomy in the Faculty of Science at York University in Toronto,  Ontario

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Paul Delaney (MSc) Senior Lecturer, Dept of Physics and Astronomy, York University, Toronto Ontario © supplied

The Dawn mission has taken eight years to reach it’s goal.  It is now orbiting the dwarf planet Ceres, after spending a year orbiting the smaller body, Vesta, a giant asteroid. It then fired its ion engine and continued on to reach Ceres which it finally reached this weekend.

It is the first satellite sent to a dwarf planet, and also the first to orbit two targets on a single mission.

Currently in high orbit at thousands of kilometers above the dwarf, Dawn will slowly spiral lower over the next month to reach a height of about 250 kilometres.

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Dawn trajectory

The mission is possible only because of use of ion propulsion which uses electricity to convert xenon gas, ionize it, and accelerate it out the back of the space craft.  The force is miniscule, but because it is constant high speeds are eventually achieved. The solar panels provide electricity for onboard systems including the 3 ion engines (only one is engaged at a time, 2 main, and one backup).

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The crater Numisia, with a diameter of 30 kilometers, show dark material both on the crater walls, and in the material that was ejected by the impact – See more at: http://dawn.jpl.nasa.gov/multimedia/vesta_dawn_gallery.asp#sthash.rheZ9bK2.dpuf © NASA/JPL-Caltech /UCLA/MPS/DLR/IDA

Dawn carries a framing camera in black and white and three colours, a visible and infrared spectrometer, a gamma ray and neutron detector, and gravity science analytics to determine mass, gravity field, principal axes, rotational axis and moments of inertia.

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Using the framing camera’s color filters breaks the reflected light into individual wavelength ranges to make many more variations in the surface composition in and around the crater Numisia visible. In such data, the researchers found the characteristic fingerprints of the mineral serpentine. © NASA/JPL-Caltech /UCLA/MPS/DLR/IDA

Delaney notes that this Dawn mission is the precursor to another set for 2016 called Osiris Rex (Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer,) which will involve a trip to an asteroid, collection of physical samples and a return to Earth.

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Extending the solar panels in the development facility, gives an idea of scale of panels and cratt

York University’s Michael Daly (PhD) is the lead Canadian instrument scientist for the instrument called OLA (OSIRIS-REx Laser Altimeter). In close collaboration with colleagues at Johns Hopkins University Applied Physics Laboratory, he will develop the data collection and processing methodologies for OLA as well as analyzing the actual OLA data. Daly is also the Deputy Canadian principal investigator (PI) for the overall science team who will participate in the analysis of the returned sample. The Canadian PI is Dr. Alan Hildebrand of the University of Calgary and science team members include Dr. Ed. Cloutis of the University of Winnipeg, Dr. Catherine Johnson of the University of British Columbia and Dr. Rebecca Ghent of the University of Toronto.

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