Thermal Emission Spectrometer: the Instrument
By S.W. Ruff
Who Built TES?

MGS Thermal Emission Spectrometer

An Instrument is Born
In response to a NASA request for instrument proposals, Dr. Phil Christensen developed the idea of TES. His experience as a graduate student at UCLA exposed him to Mars exploration. It was there that he worked with data from the Infrared Thermal Mapper. The IRTM was a more primitive version of TES that flew on the two Viking orbiters in 1976. In 1983, when NASA called for instruments to fly on board the planned Mars Observer spacecraft, Phil answered with the TES concept. He assembled many of the same IRTM engineers from the Hughes Santa Barbara Research Center (SBRC), to help design and build TES. A team of scientists also was recruited by Phil to help guide the process. One of these scientists, Dr. Hugh Kieffer, was the principal investigator for the IRTM instrument.

A Small Army of Talent
The design, development, and construction of a space-bound instrument is a major undertaking. Every component of such an instrument must survive the intense vibrations of a rocket launch and the extreme temperatures in the vacuum of space. The instrument must perform its job in this environment for extended periods of time. The men and women who produced the TES instrument at SBRC and Arizona State University responded to the challenge with great ingenuity and hard work. Some of the hands and minds behind the TES posed for a picture following a rigorous vibration test. They and the rest of the dedicated army of individuals who made TES a reality, had the privilege of signing their names to a plaque that has accompanied TES to Mars. Among the signatures is a tiny piece of Mars that will be returned to its parent body.

Mars Global Surveyor Thermal Emission Spectrometer
Carries Zagami Meteorite Back to Mars

Professor Sends Martian Meteorite Back to Home Planet
By Steve Koppes, Arizona State University

NASA's Mars Global Surveyor spacecraft is taking a small piece of the Zagami meteorite back to Mars after a visit of only 34 years on Earth.

The Zagami meteorite started off as a volcanic rock that cooled on the Martian surface about a billion years ago. The rock was flung into space after a comet or an asteroid slammed into Mars about 2.5 million years ago.

Following a long journey through the inner solar system, the meteorite fell to Earth in Zagami, Nigeria, in 1962. The return trip began Nov. 7 of last year with Surveyor's launch from Cape Canaveral, Fla. Surveyor will begin orbiting Mars on September 11.

ASU geology Professor Philip Christensen used his own funds to buy a small piece of the meteorite from a private collector to conduct tests for his thermal emission spectrometer. TES, which will map the surface minerals of Mars, is one of Surveyor's seven instruments.

Christensen chipped a sand grain from the greenish-white meteorite and attached it to a plaque on the instrument last summer. His motivation: to commemorate the accomplishments of space scientists and engineers.

"This tiny fragment of Mars represents the culmination of science and engineering capability never before seen on this planet," he said.

The grain was encapsulated in a resin bubble attached to the TES signature plaque. The resin containing the sand grain was molded into a specially designed niche on the plaque to ensure it could not break loose during the flight to Mars.

For hundreds of years, geologists and atmospheric scientists have worked to understand the composition of rocks and gases on Earth. The work has enabled researchers to develop powerful theories explaining Earth's origin and history. In the past 25 years, planetary scientists also have studied similar data from spacecraft sent to Mars to learn how it differs from Earth in composition and origin.

"As a result of these achievements, we now, for the first time in our history, know enough about our planet and the solar system we live in to be able to recognize rocks that did not originate on the Earth," Christensen said. "We are now able to identify a class of meteorites that came from Mars. The engineering capability of the human race has also reached a spectacular level - to the point where we can send multiple, complementary spacecraft from our planet to explore Mars."

During its 2-year mission, Surveyor will create a global portrait of Mars, setting the stage for the success of all future landers. Through the Zagami meteorite attached to TES, Christensen also sees it as a reminder of the past.

"This sand grain is a symbol of the achievements of all the scientists and engineers who have worked to develop the understanding, insight, and technical capability to make this first ever interplanetary 'sample return mission' a reality," Christensen said.