Like the massive white whale in Herman Melville’s 1851
classic “Moby Dick,” comets have long been considered swift,
elusive harbingers of change. So it should be of little
surprise that one of the best ways for scientists to study the
mysteries of comets is to harpoon one.
The European Space Agency’s Rosetta spacecraft is scheduled to
lift off on Feb. 26, 2004, at 2:16 am EST, from the Kourou
spaceport in French Guiana, on the northeastern coast of South
America. The launch will be the beginning of a ten-and-a-half
year odyssey to comet Churyumov-Gerasimenko that includes
flybys of Mars (2007) and the Earth (2005, 2007 and 2009).
Among the instruments aboard the Rosetta spacecraft are three
instruments funded by NASA and a key component of a fourth. The
NASA instruments will examine Churyumov-Gerasimenko from the
orbiter.
“This comet has only about three-hundred-thousandths the
gravity of Earth,” said Dr. Claudia Alexander, project
scientist for the U.S. role in the mission, from NASA’s Jet
Propulsion Laboratory (JPL), Pasadena, Calif. “The Rosetta
spacecraft will be able to make observations from as close as 2
kilometers (1.2 miles). The data from our state-of-the-art
instruments will be amazing,” she added.
Rosetta will reach Churyumov-Gerasimenko, a four-kilometer
(2.5-mile) diameter comet, in May 2014. When this rendezvous
occurs, Churyumov-Gerasimenko will be about three times as far
from the sun as the Earth is. Over the next 18 months Rosetta
will study how the comet changes as it moves closer to the sun.
In November 2014, Rosetta will drop its experiment-laden,
harpoon-firing lander on Churyumov-Gerasimenko’s icy nucleus.
“What you have to understand is that comets are primordial
remnants of the early solar system,” explained Dr. Paul
Weissman of JPL. “They are the keys to understanding the way
the whole solar system, the Earth, and how even we came into
being. And with Rosetta we will be able to observe, study and
analyze this primordial material up close for more than a
year,” he said.
JPL supplied the Microwave Instrument for Rosetta Orbiter, the
first of its type on any interplanetary mission. This
instrument can reveal the abundances of selected gases, their
temperatures, the speed at which they are coming off the
nucleus, and the temperature of the nucleus. Scientists will
use it to monitor changes in how vapors are released from the
nucleus as the coma and tail grow. They will be studying water,
carbon monoxide, ammonia and methanol, four of the most
abundant gases from comets. Dr. Samuel Gulkis of JPL’s Earth
and Space Sciences Division is principal investigator.
The Southwest Research Institute, based in San Antonio,
supplied two NASA instruments for Rosetta. One is an imaging
telescope/spectrometer capable of analyzing the composition
both of gases released by the comet and of the comet’s surface.
A goal of scientists using the instrument is to learn about the
temperatures at which comets form and evolve, by determining
the relative abundance of noble gases, such as helium, neon and
argon. Principal investigator for the ultraviolet instrument is
Dr. Alan Stern of the institute’s Space Studies Department in
Bolder, Colo.
Dr. James Burch, of the Institute’s Instrumentation and Space
Research Division, San Antonio, is principal investigator for
Rosetta’s Ion and Electron Spectrometer. This device will
measure the environment of charged particles surrounding comet
Churyumov-Gerasimenko. It will also study the interaction
between that environment and the solar wind of charged
particles speeding outward from the sun.
Key electronics for a fourth instrument, the Rosetta Orbiter
Spectrometer for Ion and Neutral Analysis, have been supplied
by Lockheed Martin Advanced Technology Center, Palo Alto,
Calif. This instrument will examine gases surrounding the
comet.
JPL, a division of the California Institute of Technology in
Pasadena, manages the microwave instrument for NASA’s Office of
Space Science, Washington, D.C.
For information about the Rosetta mission visit:
