Special activities conducted during first part of April

The month began with a non-thrusting period, scheduled to allow special activities. 1. The Gamma Ray and Neutron Detector (GRaND) was operated for about a week to collect data on the "noise" cosmic rays create in its detectors. By making such measurements, scientists will be able to compensate for this noise when GRaND Is operated at Vesta and Ceres.

2. The visible and infrared mapping spectrometer (VIR) observed the star Canopus and Mars. Both are well characterized, so these observations aid in calibrating VIR's detectors.

3. New software was transmitted to both science cameras, and tests confirmed that the software operates correctly.

4. A software patch was loaded into the spacecraft's backup main computer, bringing it to the same version already operating in the primary computer.

5. A test of the pointing accuracy of one of the ion thrusters was interrupted when software detected a signal that appeared incorrect. The combined attempt to process the response from other software and commands sent by the mission operations team led to a conflict and the computer called "safe mode." After controllers returned the spacecraft to its normal configuration, ion thrusting resumed on April 14. Meanwhile, engineers established that the software that interrupted the thrust test did so because of an unnecessary step. On April 21 they updated the software, removing that step.

The rest of the month was devoted to ion thrusting, as usual.