23 Sep 2002
Japanese Mars Probe Back on Track
Scientists have re-established communication with the Nozomi spacecraft
by Elesa Janke
Scientists at the Institute of Space and Astronautical Science (ISAS) in Japan are bringing their first interplanetary mission, Nozomi, back to life. On April 21, 2002, the spacecraft was bombarded by extremely energetic solar particles from a coronal mass ejection, which pounded the craft for over six hours and caused a temporary shutdown. But engineers are now confident that the mission will soon be back on track.
Originally known as "Planet-B," Nozomi was renamed after launch to the Japanese word for "hope." It is en route to Mars, where it will study the planet's atmosphere and ionosphere. Carrying 14 instruments from five nations, including NASA's Neutral Mass Spectrometer, the mission will bring scientists valuable information about the interaction between the atmosphere and the solar wind. The spacecraft will also send pictures back to Earth of the Red Planet's surface.
After months of hunting down the source of the problem, ISAS scientists discovered that the coronal mass ejection caused one of the electrical power converters to "latch up," knocking out the main power and freezing the onboard propellant. They have since restored communication with the spacecraft and will maneuver its attitude (orientation) when the craft re-approaches Earth later this month, allowing the propellant to unfreeze.
Launched in July 1998, the craft was originally scheduled to arrive at the Red Planet in 1999. But due to a course-correction maneuver that used more fuel than planned, Nozomi did not have enough acceleration to propel it into its planned route. It is now scheduled for a December 2003 arrival, when it will begin to fly around Mars in an oval-shaped orbit that will range from 96 to 27,000 miles from the planet's surface.