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Long wait is over for UA astronomer

By Sean McLachlan
Arizona Summer Wildcat
July 21, 1999
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Arizona Summer Wildcat

Planetary sciences Professor Robert Strom has waited 25 years to get a second look at the planet Mercury.

Now it looks like he will have his chance.

The catch - he will have to wait another nine.

In 1974, Strom and his team members watched as the unmanned probe Mariner 10 sent the first images of the little-known planet back to Earth.

That was the last probe to be sent to the small, rocky planet. While dozens of missions went to Venus, Mars, and the outer planets, Mercury was left out.

NASA has remedied the situation by accepting the proposal to launch the Mercury Surface, Space Environment, Geochemistry and Ranging mission, or Messenger for short, Strom said.

The probe will launch into space in the year 2004 and reach Mercury four years later.

Because of it's proximity to the Sun, the planet is difficult to study with ground-based telescopes.

The Mariner photos showed a rocky, cratered planet blasted by extremes of heat and cold. The sunward side baked at 900 degrees, while the dark side plunged to minus 300.

While the probe gave astronomers plenty to study, the mission was limited in scope and technology. Less than half of the planet was photographed, and many questions were left unanswered.

The Messenger probe will carry a variety of instruments to answer those questions, Strom said.

Imaging systems will determine the chemical content of the planet, while other instruments will study the planet's thin atmosphere and weak magnetic field.

Strom said that although the probe will give him a great deal of information about Mercury, the project will only cost $286 million, about the cost of one Space Shuttle mission.

The probe will also investigate if water ice is present in the shadowy craters at the north and south poles, he said.

The project is directed by the Carnegie Institution of Washington. Over a dozen institutes and universities are contributing their expertise.