At 7 a.m. PDT on Tuesday, May 18, however, the experiment team detected an anomaly that interrupted execution of the experiment. The first indication occurred when Remote Agent did not command the spacecraft's ion propulsion system to shut down as expected. While some portions of the Remote Agent software continued to operate, the component that issues commands had suspended operation.

The spacecraft was determined to be safe and healthy. The experiment software appeared active and was allowed to continue processing while the experiment team and Deep Space 1 flight team analyzed the problem. After retrieving diagnostic data from the spacecraft, a ground command was issued at 4:10 p.m. PDT Tuesday that halted the experiment.

By the time it was halted, the experiment had already achieved approximately 70 percent of its test objectives. A small bug in the very complex software has been identified as the probable cause of the suspension. A follow-up experiment is being considered for Friday, May 21, to complete the remaining objectives for the Remote Agent test.