Status Report

NASA’s Hubble Space Telescope’s Imaging Spectrograph Has Failed

By SpaceRef Editor
August 6, 2004
Filed under , ,
NASA’s Hubble Space Telescope’s Imaging Spectrograph Has Failed

TO: Distribution

FROM: 441/Operations Manager, HST Operations Project

PROGRAM: Hubble Space Telescope, HST Operations Project/Code 441

DATE OF INCIDENT: August 3, 2004 @ 16:38 GMT (12:38 PM EDT)

LOCATION OF INCIDENT: HST Space Telescope Imaging Spectrograph (STIS)


On August 3, 2004 @ 16:38 GMT (12:38 PM EDT) the Space Telescope
Imaging Spectrograph (STIS) suspended after suffering a failed command
echo check between the Control Section (CS) of the STIS Main
Electronics Box (MEB) and the Multi-Anode Micro-channel Array (MAMA)
Control Electronics (MCE).

Accompanying the Suspend was an anomalous rapid rise in the STIS input
current of approximately 1A just prior to the Suspend entry.
Additionally, a voltage dropout of the Main Electronics Box
(MEB)/Support Electronics +5 Volt power converter occurred
approximately 43 minutes prior to the Suspend. Further investigation
has now revealed a probable failure mechanism linking these anomaly
signatures. Accordingly, it is now believed that STIS’s mechanism
functions are inoperable and unrecoverable. Because STIS has been
single-string in its electronics since May 2001, it can no longer be
used for science observations.

With support from the +5 Volt power converter manufacturer
(Interpoint), investigators have duplicated the power converter
failure under loading conditions nearly identical to that seen onorbit.
The incipient failure is believed to have been in an inductor
within the power converter, which failed during the orbit night
preceding the Suspend. The inductor failure caused the power
converter +5 volt output to drop to zero volts, as seen in telemetry.
Following this dropout the converter remained relatively stable until
entry into orbit day, after which slight (and nominal) increases in
its input voltage caused its current draw to rapidly rise.

The large and rapid current draw resulted in the 1A increase in STIS
input current noted in telemetry just prior to the Suspend.

Additionally, current limiter logic within the electronics card
housing the power converter responded by reducing the supply voltage,
which in turn caused a reduction in voltage to the MAMA Control
Electronics (MCE). This, in turn, is believed to have caused the interface communications failure with the Control Section and the
subsequent Suspend action. The MAMA detectors are believed to have
been unharmed by this sequence of events since they were not active
(no high voltage on) when the anomaly occurred.

The highly probable consequence of this scenario is the total failure
of the MEB/Support Electronics +5V power converter. Since this
component is essential to the operation of all of the 8 mechanisms
within the instrument (including shutters), its demise renders those
mechanisms inoperable. A re-configuration to the Side 1 electronics
(current operations are on Side 2) is not possible. (The Side 1
electronics failed in May 2001.)

The instrument remains in Suspend mode. The Project will convene a
follow-up meeting on August 6, 2004 to continue the review and
analysis of data and to discuss a forward plan.


The STIS science program timeline was interrupted when Suspend mode
was entered. The Project and Space Telescope Science Institute will
cease scheduling STIS science. Alternate observations from other
instruments will replace STIS observations. All other HST science
instruments are functioning nominally.


The corrective actions to be taken are as follows:
Continue investigations and develop a plan to confirm the proposed
failure mechanism. Ball Aerospace, GSFC AETD, Interpoint, ST ScI, and
HST Program personnel are actively participating in the investigation.
Assess the pros and cons of leaving the STIS in Suspend mode versus
Safe Mode, pending performance of possible tests.

Form a Failure Review Board to perform a thorough investigation of the


John Gainsborough/Operations Manager/Code 441

Mike Prior/Observatory Systems Manager/Code 441

  • 5 August 2004: NASA Hubble Space Telescope Daily Report # 3668

    “Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTAR 9504: OTA SE review of PTAS processing log for SMS SA208O revealed LOL experienced in the GS Acquisition (3,2,2) @ 213/16:09:41Z. Both FGSs were in FLDV @ 213/16:13:01Z, but at 213/16:14:35Z, both returned to SSM control and successfully achieved FLDV by 213/16:15:33Z. Under investigation.”

  • 5 August 2004: NASA Hubble Space Telescope Daily Report # 3667

    “SIGNIFICANT EVENTS: STIS suspended @ 216/16:38:21Z following receipt of two Status Buffer messages (STIS 738 and STIS 734). See HSTARs 9501. Prior to the suspend, STIS was in Operate with Low Voltage on. MEB/SES + 5 Volt Power Supply (OMBMC5V) was flagging OOL low (6.29425-5 Volts) coming out of ZOE @ 216/15:57Z.”

  • SpaceRef staff editor.