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Current Status

RAX is now Complete ( Friday 5/21/99 )

Friday PM

A second remote agent experiment was conducted on Friday, May 21, starting at 7:15 a.m. Pacific Time, accomplishing all of the remaining test objectives of the remote agent team.

The remote agent was presented with three simulated failures on the spacecraft and correctly handled each event. The simulations were: 1) a failed electronics unit, which remote agent fixed by reactivating the unit; 2) a failed sensor providing false information, which remote agent recognized as unreliable and therefore correctly ignored; and 3) an attitude control thruster (a small engine for controlling the spacecraft's orientation as needed) stuck in the "off" position, which remote agent detected and compensated for by switching to a mode that did not depend on that thruster.

The only planned activity not conducted was thrusting with the ion propulsion system. The ion propulsion system is healthy but software supporting the experiment did not confirm that remote agent's command to the ion propulsion system was executed. Therefore remote agent proceeded with the rest of its plan and correctly avoided further commanding of the ion propulsion system. The cause of the missed confirmation is under investigation but because remote agent successfully operated the ion thruster earlier in the week, today's thrusting was not necessary for completing test objectives.

Once the test objectives were successfully achieved, the mission team resumed control of the spacecraft by sending a prepared command to stop remote agent at 1:30 pm.

With the remote agent experiment complete, the DS1 mission team is now turning its attention to other technologies. These include tests of DS1's two science instruments (the combined camera/spectrometer and the ion/electron spectrometer), along with collection of data to detect changes in performance, if any, of the ion propulsion system after thrusting for more than 74 days.

Friday AM

The command to start RAX was sent at 7:52 am pst. Telemetry is now flowing. For a detailed look at Remote Agent's activities, follow these links:

Thursday AM

Overnight Tuesday, the RAX team diagnosed the anomaly that had interrupted execution of the experiment earlier in the day and then replicated the problem on a ground-based spacecraft simulator. The team then designed a new, shorter experiment to achieve the remaining experiment objectives. The shortened testing scenario lasts about 6 hours.

At a project meeting in the morning of Wednesday, 5/19/99, Pacific Daylight Time, the RAX team and the DS1 spacecraft team decided that, pending further testing being conducted now, the risk of the anomaly recurring again while running the new experiment was acceptable. The team's current plan is to activate the new experiment early Friday morning, 5/21/99 PDT.

Wednesday AM

On Tuesday 5/18/99, at 7:00 am PDT the RAX team detected an anomaly that interrupted execution of the experiment. The spacecraft was determined to be safe. The RAX software appeared active and was allowed to continue processing. The RAX team together with the DS1 flight team immediately started analyzing the problem. After retrieving diagnostic data from the spacecraft, a ground command was issued on Tuesday afternoon that halted RAX. By the time it was halted, RAX had already achieved approximately 70% of its validation objectives. The team is currently analyzing the data to understand the cause of the anomaly. A followup experiment is being planned to capture the remaining technology validation objectives.

The first indication of an anomaly occurred when RAX failed to shut down the main engine (SEP) as expected. The beginning of the engine thrusting period is visible at the end of the telemetry log. There currently is no useful telemetry to display with RAX shut down, and the telemetry-to-email and telemetry-to-web services have been disabled.

Despite the anomaly, the experiment has achieved most of its objectives. We will post more information here when we hear more from the RAX team down at JPL.

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