Just as Earth-bound humans wear protective lotion to prevent sunburn, future Mars explorers will need to shield themselves against high-energy radiation from the sun and the rest of the cosmos.
Of course, to do this, they need to know the amount of radiation they might encounter along the way. Thanks to an instrument recently installed on the International Space Station, they will have a pretty good idea what to expect above the Earth and on Mars.
The instrument, known as the High-Energy Neutron Detector, has been continuously monitoring radiation at Mars since 2001 on board NASA’s Odyssey spacecraft. A twin instrument is now also monitoring radiation above Earth’s atmosphere on the space station. U.S. astronaut Michael Lopez-Alegria and Russian cosmonaut Mikhail Tyurin completed its installation Feb. 22, 2007.
Will Monitor Solar Radiation
"These instruments can be used to monitor the effects of the Sun's activity across the solar system," notes JPL planetary scientist Jeff Plaut, "especially during solar flares. We now have the same detector in two different places."
The instrument was built for the Odyssey spacecraft by the Russian space agency. As is often the case, two identical instruments were built -- a primary and a flight spare. One went to Mars and one stayed behind. At Mars, the device detected buried ice in Martian soil. Russian researchers then proposed installing the unused instrument on the space station.
Earth's magnetic field and atmosphere preclude using the device to measure neutrons interacting with water molecules at the surface. But the High-Energy Neutron Detector will be able to measure neutrons from the upper atmosphere.
"This is exciting because, usually, when we build a planetary detector, we build it for a specific environment," says Gaylon McSmith, Odyssey science manager. "It's not often we get to use the same instrument at both Mars and Earth."