Rosetta-Alice spectrograph obtains first far ultraviolet spectra of a cometary surface while orbiting Churyumov-Gerasimenko
NASA’s Alice ultraviolet (UV) spectrograph aboard the European Space Agency’s Rosetta comet orbiter has delivered its first scientific discoveries. Rosetta, in orbit around comet 67P/Churyumov-Gerasimenko, is the first spacecraft to study a comet up close.
Image Courtesy of Southwest Research Institute
The Alice ultraviolet imaging spectrometer will be the first to study a comet up close. The shoebox-sized instrument is one-third to one-half the mass of comparable UV instruments, yet with more than 10,000 times as many imaging pixels as the spectrometer aboard Galileo.
As Alice began mapping the comet’s surface last month, it made the first far ultraviolet spectra of a cometary surface. From these data, the Alice team discovered that the comet is unusually dark at ultraviolet wavelengths and that the comet’s surface — so far — shows no large water-ice patches. Alice is also already detecting both hydrogen and oxygen in the comet’s coma, or atmosphere.
“We’re a bit surprised at both just how very unreflective the comet’s surface is, and what little evidence of exposed water-ice it shows,” says Dr. Alan Stern, Alice principal investigator and an associate vice president of the Southwest Research Institute (SwRI) Space Science and Engineering Division.
Developed by SwRI, Alice is probing the origin, composition and workings of the comet, gaining sensitive, high-resolution compositional insights that cannot be obtained by either ground-based or Earth-orbital observations. The ultraviolet wavelengths Alice observes contain unique information about the composition of the comet’s atmosphere and the properties of its surface.
“As the mission progresses, we will continue to search for surface ice patches and ultraviolet color and composition variations across the surface of the comet,” says Dr. Lori Feaga, Alice co-investigator at the University of Maryland.
Alice is one of three instruments funded by NASA flying aboard Rosetta. Alice has more than 1,000 times the data-gathering capability of instruments flown a generation ago, yet it weighs less than 4 kilograms and draws just 4 watts of power. A sister Alice instrument was developed by SwRI and was launched aboard the New Horizons spacecraft to Pluto in January 2006 to study that distant world’s atmosphere. It will reach Pluto in July 2015. SwRI also built and operates Rosetta’s Ion and Electron Spectrograph (IES), another instrument with miniaturized electronic systems. With a mass of 1.04 kilograms, IES achieves sensitivity comparable to instruments weighing five times more.
To reach its comet target, the Rosetta spacecraft executed four gravity assists (three from Earth, one from Mars) and a nearly three-year period of deep space hibernation, waking up in January 2014 in time to prepare for its rendezvous with Churyumov-Gerasimenko. Rosetta also carries a lander, Philae, that will drop to the comet’s surface in November 2014, attempting the first-ever direct observations of a comet surface.
Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta’s Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Airbus Defense and Space built the Rosetta spacecraft. NASA’s Jet Propulsion Laboratory (JPL) manages the U.S. contribution of the Rosetta mission for NASA’s Science Mission Directorate in Washington, under a contract with the California Institute of Technology (Caltech). JPL also built the Microwave Instrument for the Rosetta Orbiter and hosts its principal investigator, Dr. Samuel Gulkis. SwRI (San Antonio and Boulder, Colo.) developed the Rosetta orbiter’s Ion and Electron Sensor and Alice instrument and hosts their principal investigators, Dr. James Burch (IES) and Dr. Alan Stern (Alice).
Editors: An image of the Alice ultraviolet (UV) spectrograph is available at http://www.swri.org/press/2014/alice-ultraviolet.htm.
For more information, contact Maria Stothoff, (210) 522-3305, Communications Department, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510.
Maria Martinez Stothoff | Eurek Alert!
Astronomers identify a young heavyweight star in the Milky Way
22.08.2016 | University of Cambridge
Venus-like exoplanet might have oxygen atmosphere, but not life
19.08.2016 | Harvard-Smithsonian Center for Astrophysics
Waveguides are widely used for filtering, confining, guiding, coupling or splitting beams of visible light. However, creating waveguides that could do the same for X-rays has posed tremendous challenges in fabrication, so they are still only in an early stage of development.
In the latest issue of Acta Crystallographica Section A: Foundations and Advances , Sarah Hoffmann-Urlaub and Tim Salditt report the fabrication and testing of...
Electrochemists at TU Graz have managed to use monocrystalline semiconductor silicon as an active storage electrode in lithium batteries. This enables an integrated power supply to be made for microchips with a rechargeable battery.
Small electrical gadgets, such as mobile phones, tablets or notebooks, are indispensable accompaniments of everyday life. Integrated circuits in the interiors...
Recent findings indicating the possible discovery of a previously unknown subatomic particle may be evidence of a fifth fundamental force of nature, according...
A nanocrystalline material that rapidly makes white light out of blue light has been developed by KAUST researchers.
Malignant cancer cells not only proliferate faster than most body cells. They are also more dependent on the most important cellular garbage disposal unit, the proteasome, which degrades defective proteins. Therapies for some types of cancer exploit this dependence: Patients are treated with inhibitors, which block the proteasome. The ensuing pile-up of junk overwhelms the cancer cell, ultimately killing it. Scientists have now succeeded in determining the human proteasome’s 3D structure in unprecedented detail and have deciphered the mechanism by which inhibitors block the proteasome. Their results will pave the way to develop more effective proteasome inhibitors for cancer therapy.
In order to understand how cellular machines such as the proteasome work, it is essential to determine their three-dimensional structure in detail. With its...
12.08.2016 | Event News
02.08.2016 | Event News
29.07.2016 | Event News
23.08.2016 | Information Technology
23.08.2016 | Life Sciences
23.08.2016 | Earth Sciences