During the spacecraft’s approach, the Earth appeared as a crescent. This image of the Earth was taken around the same time by the OSIRIS camera on Rosetta. Credit: ESA 2009 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA
On November 13, the European Space Agency’s comet orbiter spacecraft, Rosetta, swooped by Earth for its third and final gravity assist on the way to humankind’s first rendezvous to orbit and study a comet in more detail than has ever been attempted.
One of the instruments aboard Rosetta is the NASA-funded ultraviolet spectrometer, Alice, which is designed to probe the composition of the comet’s atmosphere and surface – the first ultraviolet spectrometer ever to study a comet up close. During Rosetta’s recent Earth flyby, researchers successfully tested Alice’s performance by viewing the Earth’s ultraviolet appearance.
“It’s been over five years since Rosetta was launched on its 10-year journey to comet Churyumov-Gerasimenko, and Alice is working well,” says instrument Principal Investigator Dr. Alan Stern, associate vice president of the Space Science and Engineering Division at Southwest Research Institute.
“As one can see from the spectra we obtained during this flyby of the Earth, the instrument is in focus and shows the main ultraviolet spectral emission of our home planet. These data give a nice indication of the scientifically rich value of ultraviolet spectroscopy for studying the atmospheres of objects in space, and we’re looking forward to reaching the comet and exploring its mysteries.”