Artist's impression of CHAMP in orbit after launch. Photo: Astrium

The German CHAMP Earth sciences satellite is proceeding successfully through a series of on-orbit checks of its systems even though controllers believe the craft was hit as the Cosmos rocket's nose cone separated during launch two weeks ago.

CHAMP was hurled into Earth orbit on July 15 from the Plesetsk Cosmodrome in Russia.

The satellite separated from the second stage of the Cosmos while over Hawaii just half-an-hour after launch. After a telemetry pass over the NASA McMurdo tracking station in Antarctica, it was determined that the CHAMP spacecraft was in a near-perfect orbit with an apogee, or high point, of 475 km, a perigee, or low point, of 422 km, and an inclination of 87.2744 degrees.

Shortly after arriving in orbit, the attitude control system was brought on-line to keep the craft on course.

On July 16, power supply systems from the solar panels were successfully checked out, as were the on-board computers and command and data handling systems. The 4 meter-long boom was also successfully deployed. However, one of the six sun trackers that would be used should the spacecraft go into safe mode failed. Also on July 16, the GPS receiver was switched on and verified to be functioning properly, four main star sensors used to aid in attitude control were turned on successfully, and the magnetometers were checked out and brought into service.

On July 17, another of the six Earth/sun sensors failed. After analyzing telemetry data from both the launch and the time in orbit, flight controllers concluded that these two failures were probably caused by a collision with the payload fairing during its jettison. Also, on the same day, ground engineers discovered that the main navigation mode was using more nitrogen propellant than was expected.

Flight controllers also discovered off nominal behavior of the battery charge control system. It is thought that this problem was due to a solar magnetic storm on July 16 and engineers took preventive measures that successfully ensured good health of all the batteries for use in future operations.

CHAMP under construction. Photo: GFZ Potsdam

The next day, flight controllers in Germany successfully achieved stable fuel consumption of the craft's gaseous nitrogen fuel supply. This break-through allowed the planned five-year mission to again become reality.

By the middle of last week, all science experiments had been turned on and were operating as planned.

CHAMP is set to begin regular scientific observations some time in early August.

CHAMP is on a mission to study the interaction of all Earth's systems and the way those interactions effect life on Earth. Magnetometers will study our planet's magnetic field, a GPS receiver will both accurately track the orbit of the spacecraft and study the upper atmosphere and ionosphere. For the atmospheric studies, the GPS signals will be refracted from the upper atmosphere back up to the GPS receiver on CHAMP. Scientists hope that the data from the refracted signals will be able to be converted so that they can tell the contents of the upper atmosphere, such as water vapor and temperature, for the very first time.

Accelerometers aboard the craft will be used to monitor the orientation of the spacecraft for gravitational studies.