Rosetta 'Alice' spectrometer reveals Earth's ultraviolet fingerprint in Earth flyby

Jan 14, 2010
During the spacecraft’s approach, the Earth appeared as a crescent. The drawing (generated by the SwRI-developed Geometry Visualization tool) shows the appearance of the Earth as seen from the spacecraft. The red outline shows the orientation of the long slit off the Alice spectrograph. Credit: SwRI

On Nov. 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 flyby, researchers successfully tested Alice's performance by viewing the Earth's ultraviolet appearance.

"It's been more than 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. We're looking forward to reaching the comet and exploring its mysteries."

The 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

Dr. Paul Feldman, professor of Physics and Astronomy at The Johns Hopkins University, and an Alice co-investigator, has studied the Earth's from the early days of space studies. "Although the Earth's ultraviolet emission spectrum was one of the first discoveries of the space age and has been studied by many orbiting , the Rosetta flyby provides a unique view from which to test current models of the Sun's interaction with our atmosphere."

SwRI also developed and will operate the NASA-funded Ion and Electron Sensor aboard Rosetta. IES will simultaneously measure the flux of electrons and ions surrounding the over an energy range extending from the lower limits of detectability near 1 electron volt, up to 22,000 electron volts.

Thanks to an Earth gravity assist swing-by in November, Rosetta is now on a course to meet its cometary target in mid-2014. Before reaches its main target, it will explore a large asteroid called Lutetia, in July. The Alice UV spectrometer will be one of the instruments mapping this ancient asteroid.

Explore further: Curiosity brushes 'Bonanza king' target anticipating fourth red planet rock drilling

add to favorites email to friend print save as pdf

Related Stories

Rosetta and New Horizons watch Jupiter in joint campaign

Mar 30, 2007

ESA’s Rosetta and NASA’s New Horizons are working together in their joint campaign to observe Jupiter. A preliminary analysis of the data from Rosetta’s Alice ultraviolet spectrometer indicates that the ...

Rosetta, New Horizons team up

Mar 02, 2007

ESA and NASA are mounting a joint campaign to observe Jupiter over the next few weeks with two different spacecraft. Rosetta will watch the big picture from its current position near Mars, whilst New Horizons ...

Boosting the accuracy of Rosetta's Earth approach

Oct 19, 2007

Yesterday, 18 October at 18:06 CEST, the thrusters of ESA’s comet chaser, Rosetta, were fired in a planned, 42-second trajectory correction manoeuvre designed to 'fine tune' the spacecraft's approach to ...

Rosetta's final Earth boost

Nov 04, 2009

ESA's comet chaser Rosetta will swing by Earth for the last time on 13 November to pick up energy and begin the final leg of its 10-year journey to comet 67P/Churyumov-Gerasimenko. ESA's European Space Operations ...

Rosetta monitors Deep Impact

Jun 20, 2005

ESA’s comet chaser Rosetta will take part in one of the world’s largest astronomical observation campaigns - the Deep Impact event - while on its cruise to Comet 69P/Churyumov-Gerasimenko. Rosetta will be ...

Rosetta closes in on Earth -- a second time

Nov 08, 2007

ESA’s comet chaser, Rosetta, is on its way to its second close encounter with Earth on 13 November. The spacecraft’s operators are leaving no stones unturned to make sure Earth’s gravity gives it the ...

Recommended for you

Australian amateur Terry Lovejoy discovers new comet

18 hours ago

It's confirmed! Australian amateur astronomer Terry Lovejoy just discovered his fifth comet, C/2014 Q2 (Lovejoy). He found it August 17th using a Celestron C8 fitted with a CCD camera at his roll-off roof ...

Students see world from station crew's point of view

Aug 19, 2014

NASA is helping students examine their home planet from space without ever leaving the ground, giving them a global perspective by going beyond a map attached to a sphere on a pedestal. The Sally Ride Earth ...

Mars deep down

Aug 19, 2014

Scarring the southern highlands of Mars is one of the Solar System's largest impact basins: Hellas, with a diameter of 2300 km and a depth of over 7 km.

User comments : 0