An artist's concept of the Rosetta spacecraft and its lander headed to Comet Wirtanen. Credit: ESA

An instrument called ROSINA, with key components designed and built at the Lockheed Martin Advanced Technology Center (ATC) in Palo Alto, will be launched early next year on the European Space Agency's (ESA) Rosetta spacecraft. The goal of the ambitious international mission is to catch up with, orbit, and land on Comet Wirtanen in an effort to answer questions about the origin of our Solar System. "Rosetta has the most instruments of any spacecraft -- that makes it challenging and one of the most exciting missions ever," said Dr. Claudia Alexander, U.S. Project Scientist for the mission and NASA Jet Propulsion Laboratory (JPL) scientist. "We're going to see some big discoveries, just like Galileo and Cassini."

Chosen among hundreds for its uniquely high volatile and organic material content, Comet Wirtanen was discovered by Carl A. Wirtanen on January 17, 1948 at the University of California, Santa Cruz Lick Observatory. His wife Edith Wirtanen, who still devotes time to the Visitors' Services Department at Lick, succeeds him. "Carl would have been very excited about the Rosetta mission," said Mrs. Wirtanen. "He wanted to see what was inside the comet like everybody else. We always teased him about discovering comets--that you'd get a medal for each comet you discovered and at this rate, that he could use them to tile the floor. He discovered about five of them. He had no idea that it [Comet Wirtanen] would be this famous."

Comets are icy preserves of the material present during the formation of the solar system, unhindered by the Sun's scorching effects. Ground-based studies show strong indications that complex organic molecules, such as hydrogen, carbon, oxygen and nitrogen, sit beneath the surface of comets. These elements make up nucleic and amino acids, which are essential for creating life. Was life on Earth spawned by a chance comet encounter? ATC helped develop ROSINA with the University of Bern and other institutions to help scientists find the answer.

The Rosetta Stone was used to decipher the meaning of a language -- the hieroglyphics of ancient Egypt -- that previously eluded anyone who dared to try. ESA's spacecraft aims to be the Rosetta Stone of the solar system -- the decipherer of the many secrets comets hold in their icy, dusty cores. Leading theories regarding their physical and chemical composition, mass, surface and evolution differ widely. Only with an instrument like the one designed with an international team including the ATC can the various theories be tested.

This artist's impression shows the Rosetta lander on the comet's surface. Credit: ESA

ROSINA -- for Rosetta Orbiter Spectrometer for Ion and Neutral Analysis -- will perform composition analysis on the Rosetta mission. A mass spectrometer uses electric and magnetic fields to map the mass of an ion to its chemical composition.

ROSINA will analyze particles in the comet's atmosphere by mass, physical and chemical composition, temperature, and velocity. Such data will yield important results about the formation, position and origin of comets, the similarities between cometary material and the interstellar material present during the birth of the solar system, and help to determine relationships between comets and asteroids.

As the highest resolution mass spectrometer ever flown, ROSINA will measure the isotopes Carbon 12 and Carbon 13, which differ by a single neutron. Such elements are used in carbon dating, which determines the age of an organism. "The Carbon 12 to Carbon 13 ratio in a comet tells us about the material that was present in the dense interstellar medium that formed our Sun. Only comets have this information frozen within them," said Dr. Stephen Fuselier of Lockheed Martin's ATC and U.S. lead co-investigator for the ROSINA instrument.

"One of the mission's most exciting pieces of information will come from the ROSINA instrument," said Alexander. "ROSINA will perform carbon dating on the comet's nucleus. One of the things that we don't know is whether comets were part of our solar system in the beginning. Figuring out the age of the surface of the comet will help us to figure out what their role was to make the solar system come to being and whether they bring in particles from outside the solar system."

ROSINA will also find out what generation star our Sun is. "ROSINA will determine the metal content of the interstellar medium that formed our Sun by using the Carbon 12 and 13, and carbon monoxide and nitrogen ratios found inside comets," said Fuselier. "If it is very metal rich, we know our Sun is not a second generation star because the Big Bang only created hydrogen and helium. By determining the metalloids inside the comet we can also deduce the size of the star that created our Sun."

Rosetta's ten-year mission begins with a launch in January 2003 from Kourou, French Guiana. Flying first out to Mars and then back to Earth, Rosetta will use the gravitational momentum from both planets to slingshot it farther into space. It will then pass by asteroid Otawara in July 2006 and complete another Earth gravity assist in November 2007. Rosetta will fly by asteroid Siwa in July 2008 and finally reach comet Wirtanen in November 2011. The spacecraft will spend two years mapping and examining the surface using remote sensing, analyzing dust and vapors, and finally releasing a lander.

The Rosetta orbiter swoops over the lander soon after touchdown on the nucleus of Comet 46P/Wirtanen. Credit: ESA

During its mission, Rosetta will fly by asteroids Otawara and Siwa on its eight-year journey to comet Wirtanen. Otwara is the smallest asteroid to be visited by a spacecraft; Siwa is the largest. Asteroids are referred to as planetesimals -- tiny seeds that were denied the chance to accrete into anything larger. At times containing impact marks nearly as big as the size of the asteroid itself, asteroid collisions tell us about the turbulent nature of our solar system during its formation. Analyzing their composition and mass can help determine the likelihood of an asteroid-Earth collision.

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