# Summary

An Anomaly Review Team (ART) was formed to investigate the recurring
upset of the GGS Telemetry Module (GTM) onboard the POLAR spacecraft.
Since launch the primary GTM side (GTM-1) upset four times between May
1998 and September 2000. A separate anomaly required the switchover to
the redundant GTM side (GTM-2) in March 2001. Since the switchover GTM-2
has upset eight times (see summary in Tables 1 & 2 below). The upset
anomaly is characterized by a corruption of all real-time data, with the
exception of parameters for the minor frame sync pattern and the minor
frame number. All housekeeping and science data is corrupted for the
duration of the anomaly. This corrupt data is also recorded to the
onboard tape recorders and is likewise corrupt when the recorded data is
downlinked and analyzed.

The primary focus of this ART was on the possible reasons for the
upsets. A secondary focus was to determine the science impact and if
proper recovery procedures are in place. This report documents the
history and status of the GTM, the investigation undertaken by the ART,
and the findings of that investigation. In summary, it is not possible
to definitely determine a cause of the upsets at this time, but it is
believed to be caused by environmental conditions in the mission orbit.
At this time the flight operations team (FOT) is able to recover from
the upset quickly and return all the instruments to science mode while
minimizing the impact to science data collection. Currently the upset is
an inconvenience to the missions operations but is recoverable.

# Background

The GTM collects and formats spacecraft telemetry and instrument science
data into a continuous bit stream. A block diagram is shown in Figure 1.
As shown in the figure the GTM is internally redundant.

The telemetry stream is formatted in one of four fixed schemes, as
follows:

-   Science Mode -- nominal mode for the mission, with most of the
    available bandwidth utilized by the instruments

-   Maneuver Mode -- used during orbit or attitude adjust maneuvers and
    during deployments. It provides higher repetition rates for certain
    Attitude Control and Determination Subsystem (ACADS) channels at the
    expense of some science data.

-   Contingency Mode -- designed for use in the event of a total failure
    of the despun platform. Science data is collected only from the main
    body instruments, with no provision for science data from despun
    instruments. Currently used to provide increased bandwidth to the
    main body instruments during periods when the platform instrument
    data are not particularly useful.

-   Engineering Mode -- only utilized during recovery from certain
    spacecraft anomalies. The bite rate is much slower, at only 2% of
    the other modes. The entire bandwidth is occupied by spacecraft
    subsystem data without any instrument science data.

The GTM responds to the mode select commands received serially from the
Command Distribution Unit (CDU) and changes mode at the end of the major
frame currently in progress.

![](media/image1.jpeg){width="6.706944444444445in"
height="7.173611111111111in"}

### Figure 1: GTM Block Diagram

During each of the GTM events all of real-time housekeeping and science
data is corrupted, with the exception of parameters for the minor frame
sync pattern and the minor frame number. This corrupt data is also
recorded to the onboard tape recorders and is likewise corrupt when the
recorded data is downlinked and analyzed.

  ----------------- -------------------------- --------------------------
  **Upset \#**      **Date**                   **Time**

  1                 05/06/1998                 08:15 UT

  2                 09/30/1998                 14:00 UT

  3                 10/22/1998                 21:48 UT

  4                 09/22/2000                 01:26 UT

  Switch to GTM-2   03/27/2001                 22:10 UT
  ----------------- -------------------------- --------------------------

### Table 1: GTM-1 Upset Summary

  ----------------- -------------------------- --------------------------
  **Upset \#**      **Date**                   **Time**

  1                 11/10/2003                 18:26 UT

  2                 11/17/2003                 15:13 UT

  3                 11/24/2003                 16:38 UT

  4                 12/06/2003                 21:44 UT

  5                 12/18/2003                 09:36 UT

  6                 02/12/2004                 03:04 UT

  7                 03/03/2004                 20:14 UT

  8                 04/03/2004                 09:04 UT
  ----------------- -------------------------- --------------------------

### Table 2: GTM-2 Upset Summary

For the first eight GTM upsets, the FOT followed the *Real-Time
Telemetry Downlink Anomaly* contingency procedure (PCPG-05) to recover
the GTM to its previous configuration. To accomplish this, the
contingency flow calls a previously developed TPOCC Spacecraft Test and
Operating Language (TSTOL) procedure that was designed to switch GTM
sides in the blind. The TSTOL procedure performs the following steps:

1.  Place the digital tape recorders (DTR) in standby (in case a data
    rate change is required),

2.  Disable clock to both GTMs,

3.  Select the GTM to be used,

4.  Select the telemetry mode for the Command and Attitude Processor
    (CAP), GTM, and Remote Interface Unit (RIU)

5.  Re-enable the clock to the correct side of the GTM.

6.  Place the DTR back into record mode to resume science data
    collection.

The spacecraft subsystems were never endangered by the anomaly and
remained healthy.

A consequence of the GTM upset is that several of the instruments must
also be recovered. The following instrument anomalies follow almost
every GTM upset:

1.  TIMAS telemetry latchup.

2.  TIDE telemetry latchup.

3.  MFE ADC upset.

4.  HYDRA eeprom write protect flag switches to the \"enabled\" state

Immediately following recovery of the GTM, the following instrument
recovery is initiated:

1.  Reset MFE ADC and restart MagAz/El processing.

2.  Reset HYDRA EEPROM write protect flag to the \"disabled\" state.

3.  Return TIMAS to full operation.

4.  Return TIDE to full operation.

The exact reason for the subsequent instrument anomalies was originally
suspected to be due to the loss of clock sync in the recovery procedure
when disabling the GTM.

After several GTM upsets, analog telemetry parameters were found to have
invalid or altered readings. Telemetry parameters affected by GTM Side-1
upsets remained impaired after the switch to GTM Side-2. The affected
parameters are not considered crucial to the monitoring of spacecraft
health and safety. A history of the affected telemetry parameters is
given in Appendix A.

Review of the design information noted that several actions are required
when changing the telemetry format. Each format-sensitive component has
to be commanded to change format. This means one or more commands to
each instrument, to the RIU, to Flight Software (FSW) in the currently
selected CAP, and to the GTM itself. Data will be garbled if these
components are in any way mismatched, therefore, all of these commands
should be executed within a single major frame, to take effect together
at the next major frame sync pulse. For operational simplicity the
individual commands are stored in macros for rapid execution by the CAP
to insure that all commands are executed within the same major frame. If
this condition is adhered, there should be no interruption in the data
for changes between science, maneuver, and contingency formats. However,
changes into and out of the engineering format have complications
associated with changes in bit rate.

At the ART meeting following the fourth GTM-2 upset, it was suggested
that for future recovery operations, only the telemetry mode commands of
the recovery procedure be sent to determine which command or commands
were directly responsible for recovering from the GTM upset. It was
hypothesized that the GTM clock disable/enable commands were not
necessary for recovery and may be contributing to the upset of the
science instruments as noted above.

After the fifth GTM-2 upset on December 18, 2003, the telemetry select
commands were sent individually to observe each potential response. The
CAP science mode telemetry select was sent first without affect. The GTM
select command was then sent, and the telemetry was restored. This
demonstrated that the upset is occurring in the GTM itself and that the
clock disable/enable commands were not necessary for recovery. The
revised recovery process using only the telemetry select commands has
been used for all subsequent upsets. Unfortunately, the associated
instrument anomalies still occurred. The cause of the associated
instrument anomalies is still unknown, but they are now believed to
occur when the GTM is upset and not during the associated recovery.

# Current Status

After the eighth GTM-2 upset on April 3, 2004, the GTM and instruments
were fully recovered. Currently the GTM is working properly, and the
spacecraft and instruments are healthy.

# ART Charter

1)  Analyze all relevant telemetry and other data to assess; if
    possible, the cause of the GTM upsets.

2)  Determine, if possible, any detrimental affects from the upsets on
    the GTM.

3)  Review the recovery procedures and the impact on the science data
    collection.

4)  Issue a recommendation regarding the recovery of the GTM.

5)  Produce a report detailing the findings of the ART.

# ART Membership

Scott Glubke / GSFC 444 / SSMO Spacecraft Engineering Lead (ART
Chairman)

Steve Odendahl / GSFC 444 / POLAR Mission Director\
Patrick Crouse / GSFC 444 / SSMO Deputy Project Manager

Terry Smith / GSFC 561 / C&DH Engineer\
Steve Hearn / LMECO / GGS-POLAR Spacecraft Lead Engineer

Barbara Giles / GSFC 692 / POLAR Project Scientist

Mike Machado / HTSI / POLAR FOT Lead

# ART Investigation

## Telemetry review

Following each anomaly the FOT would review the telemetry data to
determine when the upset occurred. Because the upset causes all the
telemetry to be corrupted, data review post-upset is not possible. This
is also the reason that the cause for the associated instrument
anomalies is unknown.

## Failure Analysis

Various schematic diagrams of the GTM subassemblies were obtained from
the FOT. These diagrams were reviewed with the GSFC C&DH engineer, Terry
Smith. A complete set of schematics was not available so only a limited
failure analysis was done. Despite the limited information, several
potential components were identified that could be the specific
component affected. Without further design details or access to the
design engineers, further identification of the affected components is
not possible. A task allowing discussion with the design engineers has
been initiated but is not in place at this time.

As previously noted the FOT found that sending the GTM telemetry select
command always cleared the errors. Knowing this, the limited schematic
diagrams were reviewed to identify what components might be affected.
Terry Smith was able to narrow down the problem to three potential
sources:

1.  Component U28 (CD4035B) -- a CMOS 4-Stage Parallel In/Parallel Out
    Shift Register on the GTM Miscellaneous Logic Board. This part
    receives the serial mode command from the Command Distribution Unit
    (CDU) and selects the GTM telemetry format. It is the only register
    that gets upset as a result of the GTM telemetry select command.
    Corruption of the contents of this shift register is the only
    possible explanation for the errors that we are seeing and the
    clearing of the error condition.

2.  Component U28 could be getting corrupted by noise on the GTM +10 V
    Line. Very little of the electronics requires +10V. U28 is one of
    the few ICs that are powered from this line. The noise could be
    coming from the GTM power supply.

3.  Component U28 could be getting corrupted by noise on the Mode
    Command Lines from the Command Distribution Unit. However, this is
    rather unlikely because it would require that noise be present
    simultaneously on both the Mode Command Start line and the Mode
    Command Clock Line.

## Additional Testing/Investigation

No additional testing has been done after the identification of the GTM
as the component being upset. No other testing is planned at this time.

# ART Discussion & Findings

The GTM has been identified as the source of the telemetry corruption.
Some suspected environmental effect is upsetting the telemetry format
definition within the GTM and subsequently causing the instrument
anomalies. Even though components have been identified as having the
potential to be upset, further refinement is not possible without
additional design details. Once potential upset scenarios have been
reviewed and resolved, individual component susceptibility to
environmental conditions (e.g. proton flux, radiation, etc.) can be
reviewed.

With the exception of the loss of several non-crucial analog telemetry
points there doesn't appear to be any detrimental affect on spacecraft
subsystems or instruments from the GTM upsets and no indication of
potential failure. The only impact is the loss of science and
engineering data for a period of time. Streamlining the FOT recovery
procedures and close cooperation with the instrument teams has minimized
the overall data impact.

# Final Disposition & Recommendation

The final recommendation of the ART is to continue the mission
operations with GTM-2. The spacecraft and instruments are currently
healthy and operating properly. The upset of the GTM causes a loss of
science data but does not appear to have any potential impacts or
failure of the GTM. Procedures exist to successfully recover from upsets
with minimal science data impact. Further review of design information,
discussions with design engineers, and analysis to determine the root
cause will occur in the future as information becomes available. No
other actions are necessary.

#### GTM Upset #1

  -------------- ----------- ---------------------- -----------------------------
  **Mnemonic**   **Event     **Comment**            **Status**
                 Effect**                           

  H_TH1          Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  H_TH2          Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  H_TPPA1        Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  H_TPPA2        Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  M_ELTEMP       Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  M_IBTEMP       Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  M_OBTEMP       Corrupted   Corrupt value not      Not required for operations
                             identifiable           

  ISIESTEMP      Biased      Reading Biased By      Not required for operations
                             \~+18° C               
  -------------- ----------- ---------------------- -----------------------------

#### GTM Upset #2: No Apparent Damage

#### GTM Upset #3

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| D      | Cor    | Corrupt value not   | Represents powered-off side |
| GTM25V | rupted | identifiable        | of GTM.                     |
|        |        |                     |                             |
|        |        |                     | Not required for operations |
|        |        |                     | while unit is powered off.  |
+--------+--------+---------------------+-----------------------------+
| DG     | Cor    | Corrupt value not   | Represents powered-off side |
| TM210V | rupted | identifiable        | of GTM.                     |
|        |        |                     |                             |
|        |        |                     | Not required for operations |
|        |        |                     | while unit is powered off.  |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2128 |        | approximately one   | of GTM.                     |
|        |        | decimal count       |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2256 |        | approximately two   | of GTM.                     |
|        |        | decimal counts      |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2384 |        | approximately three | of GTM.                     |
|        |        | decimal counts      |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2512 |        | approximately four  | of GTM.                     |
|        |        | decimal counts      |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+

GTM Upset #4

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| NX     | A      | Reading bounces     | Not required for operations |
| 2INTTP | ltered | between zero and    | while unit is powered off.  |
|        |        | one decimal count   |                             |
|        |        |                     | Represents un-powered       |
|        |        |                     | reading of temperature.     |
+--------+--------+---------------------+-----------------------------+
| NX     | Biased | Powered-off reading | Only powered-off reading is |
| 1PWLVL |        | biased one decimal  | affected.                   |
|        |        | count               |                             |
|        |        |                     | Does not affect monitoring  |
|        |        |                     | of operational unit.        |
+--------+--------+---------------------+-----------------------------+
| NX     | Biased | Reading biased one  | Not required for operations |
| 2PWLVL |        | decimal count       | while unit is powered off   |
+--------+--------+---------------------+-----------------------------+
| NS     | A      | Reading bounces     | Not required for operations |
| 2PWLVL | ltered | between zero and    | while unit is powered off.  |
|        |        | one decimal count   |                             |
|        |        |                     | Represents un-powered       |
|        |        |                     | reading.                    |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2128 |        | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2256 |        | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2384 |        | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Biased              | Represents powered-off side |
| TM2512 |        | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| GMTRBI | Biased | Biased              | Represents powered-off side |
|        |        | approximately one   | of DPM.                     |
|        |        | decimal count       |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+

#### Post GTM Upset #4: 00/267/15:00 UTC

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| NX     | A      | Powered-off reading | Only powered-off reading is |
| 1PWLVL | ltered | bounces between     | affected.                   |
|        |        | zero and one        |                             |
|        |        | decimal count       | Does not affect monitoring  |
|        |        |                     | of operational unit.        |
+--------+--------+---------------------+-----------------------------+
| NS     | Re     | Apparently          | Not required for operations |
| 2PWLVL | stored | restored. Reading   | while unit is powered off.  |
|        |        | unexpectedly        |                             |
|        |        | returned to zero    | Represents un-powered       |
|        |        | counts.             | reading.                    |
+--------+--------+---------------------+-----------------------------+
| DG     | Rest   | Reading             | Represents powered-off side |
| TM2128 | ored\* | unexpectedly        | of GTM.                     |
|        |        | returned to biased  |                             |
|        |        | value seen prior to | Not required for            |
|        |        | Upset #4            | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Rest   | Reading             | Represents powered-off side |
| TM2256 | ored\* | unexpectedly        | of GTM.                     |
|        |        | returned to biased  |                             |
|        |        | value seen prior to | Not required for            |
|        |        | Upset #4            | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Rest   | Reading             | Represents powered-off side |
| TM2384 | ored\* | unexpectedly        | of GTM.                     |
|        |        | returned to biased  |                             |
|        |        | value seen prior to | Not required for            |
|        |        | Upset #4            | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Rest   | Reading             | Represents powered-off side |
| TM2512 | ored\* | unexpectedly        | of GTM.                     |
|        |        | returned to biased  |                             |
|        |        | value seen prior to | Not required for            |
|        |        | Upset #4            | operations.                 |
+--------+--------+---------------------+-----------------------------+

**GTM Side Switch**

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| NX     | Re     | Reading returned to | Not required for operations |
| 2INTTP | stored | zero counts         | while unit is powered off.  |
|        |        |                     |                             |
|        |        |                     | Represents un-powered       |
|        |        |                     | reading of temperature.     |
+--------+--------+---------------------+-----------------------------+
| NX     | Re     | Off reading         | Powered-off value restored  |
| 1PWLVL | stored | returned to zero    | after switch                |
|        |        | counts              |                             |
+--------+--------+---------------------+-----------------------------+
| NX     | Re     | Reading returned to | Not required for operations |
| 2PWLVL | stored | zero counts         | while unit is powered off   |
+--------+--------+---------------------+-----------------------------+
| D      | Re     | Restored after      | Restored by GTM Side switch |
| GTM25V | stored | switch to GTM Side  |                             |
|        |        | 2                   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | Re     | Restored after      | Restored by GTM Side switch |
| TM210V | stored | switch to GTM Side  |                             |
|        |        | 2                   |                             |
+--------+--------+---------------------+-----------------------------+
| D      | Cor    | Corrupted after     | Represents powered-off side |
| GTM15V | rupted | switch to GTM Side  | of GTM.                     |
|        |        | 2                   |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Cor    | Corrupted after     | Represents powered-off side |
| TM110V | rupted | switch to GTM Side  | of GTM.                     |
|        |        | 2.                  |                             |
|        |        |                     | Not required for            |
|        |        | Value mimics        | operations.                 |
|        |        | mnemonic DSRVOER2   |                             |
|        |        | in Science          |                             |
|        |        | Telemetry Format.   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | Re     | Restored after      | Restored by GTM Side switch |
| TM2128 | stored | switch to GTM Side  |                             |
|        |        | 2                   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | Re     | Restored after      | Restored by GTM Side switch |
| TM2256 | stored | switch to GTM Side  |                             |
|        |        | 2                   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | Re     | Restored after      | Restored by GTM Side switch |
| TM2384 | stored | switch to GTM Side  |                             |
|        |        | 2                   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | Re     | Restored after      | Restored by GTM Side switch |
| TM2512 | stored | switch to GTM Side  |                             |
|        |        | 2                   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Values resemble GTM | Represents powered-off side |
| TM1128 |        | Side 1 values prior | of GTM.                     |
|        |        | to GTM side switch  |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Values resemble GTM | Represents powered-off side |
| TM1256 |        | Side 1 values prior | of GTM.                     |
|        |        | to GTM side switch  |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Values resemble GTM | Represents powered-off side |
| TM1384 |        | Side 1 values prior | of GTM.                     |
|        |        | to GTM side switch  |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | Biased | Values resemble GTM | Represents powered-off side |
| TM1512 |        | Side 1 values prior | of GTM.                     |
|        |        | to GTM side switch  |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| GMTRBI | Biased | Biased reduced      | Represents powered-off side |
|        |        | approximately       | of DPM.                     |
|        |        | one-half decimal    |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| H_TH1  | A      | New pattern to      | Not required for operations |
|        | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| H_TH2  | A      | New pattern to      | Not required for operations |
|        | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| H      | A      | New pattern to      | Not required for operations |
| _TPPA1 | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| H      | A      | New pattern to      | Not required for operations |
| _TPPA2 | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | New pattern to      | Not required for operations |
| ELTEMP | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | New pattern to      | Not required for operations |
| IBTEMP | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | New pattern to      | Not required for operations |
| OBTEMP | ltered | corrupt values      |                             |
+--------+--------+---------------------+-----------------------------+
| ISI    | Cor    | No longer simply    | Not required for operations |
| ESTEMP | rupted | biased reading      |                             |
+--------+--------+---------------------+-----------------------------+

#### GTM Upset #5

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| NX     | A      | Reading bounces     | Not required for operations |
| 2INTTP | ltered | between zero and    | while unit is powered off.  |
|        |        | one decimal count   |                             |
|        |        |                     | Represents un-powered       |
|        |        |                     | reading of temperature.     |
+--------+--------+---------------------+-----------------------------+
| NS     | A      | Reading bounces     | Not required for operations |
| 2PWLVL | ltered | between zero and    | while unit is powered off.  |
|        |        | one decimal count   |                             |
|        |        |                     | Represents un-powered       |
|        |        |                     | reading.                    |
+--------+--------+---------------------+-----------------------------+
| R      | Biased | Reading Biased By   | Thruster Catalyst Bed       |
| RCBnTP |        | Average of +3° C    | Temperatures continue to    |
|        |        |                     | operate normally with       |
| (n=1   |        |                     | positive bias noted         |
| to 12) |        |                     |                             |
+--------+--------+---------------------+-----------------------------+

#### GTM Upset #6

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New pattern of      | Represents powered-off side |
| TM110V | ltered | corrupt values.     | of GTM.                     |
|        |        |                     |                             |
|        |        | No longer mimics    | Not required for operations |
|        |        | DSRVOER2.           |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1256 | ltered | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1384 | ltered | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1512 | ltered | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| H_TH1  | A      | Returned to         | Not required for operations |
|        | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| H_TH2  | A      | Returned to         | Not required for operations |
|        | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| H      | A      | Returned to         | Not required for operations |
| _TPPA1 | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| H      | A      | Returned to         | Not required for operations |
| _TPPA2 | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Returned to         | Not required for operations |
| ELTEMP | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Returned to         | Not required for operations |
| IBTEMP | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Returned to         | Not required for operations |
| OBTEMP | ltered | post-Upset #1       |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| R      | Biased | Reading             | Thruster Catalyst Bed       |
| RCBnTP |        | Additionally Biased | Temperatures continue to    |
|        |        | By Average of +8° C | operate normally with net   |
| (n=1   |        |                     | positive bias noted         |
| to 12) |        |                     |                             |
+--------+--------+---------------------+-----------------------------+

#### GTM Upset #7

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| NX     | Re     | Apparently restored | Not required for operations |
| 2INTTP | stored | after upset.        | while unit is powered off.  |
|        |        |                     |                             |
|        |        | Reading returned to | Represents un-powered       |
|        |        | zero counts.        | reading of temperature.     |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | Returned to         | Represents powered-off side |
| TM110V | ltered | post-GTM Switch     | of GTM.                     |
|        |        | pattern.            |                             |
|        |        |                     | Not required for            |
|        |        | Value mimics        | operations.                 |
|        |        | mnemonic DSRVOER2   |                             |
|        |        | in Science          |                             |
|        |        | Telemetry Format.   |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1128 | ltered | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1256 | ltered | approximately one   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | count               | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1384 | ltered | approximately two   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | counts              | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | New value biased    | Represents powered-off side |
| TM1512 | ltered | approximately two   | of GTM.                     |
|        |        | additional decimal  |                             |
|        |        | counts              | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| H_TH1  | A      | Returned to         | Not required for operations |
|        | ltered | post-GTM Switch     |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| H_TH2  | A      | Returned to         | Not required for operations |
|        | ltered | post-GTM Switch     |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| H      | A      | Returned to         | Not required for operations |
| _TPPA1 | ltered | post-GTM Switch     |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| H      | A      | Returned to         | Not required for operations |
| _TPPA2 | ltered | post-GTM Switch     |                             |
|        |        | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Altered to new      | Not required for operations |
| IBTEMP | ltered | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Altered to new      | Not required for operations |
| OBTEMP | ltered | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| R      | Biased | Reading             | Thruster Catalyst Bed       |
| RCBnTP |        | Additionally Biased | Temperatures continue to    |
|        |        | By Average of +14°  | operate normally with net   |
| (n=1   |        | C                   | positive bias noted         |
| to 12) |        |                     |                             |
+--------+--------+---------------------+-----------------------------+

#### GTM Upset #8

  -------------- ---------- ---------------------- -----------------------------
  **Mnemonic**   **Event    **Comment**            **Status**
                 Effect**                          

  M_IBTEMP       Altered    Altered to new pattern Not required for operations

  M_OBTEMP       Altered    Returned to post-GTM   Not required for operations
                            Switch pattern         
  -------------- ---------- ---------------------- -----------------------------

**GTM Upset #9**

+--------+--------+---------------------+-----------------------------+
| **Mnem | *      | **Comment**         | **Status**                  |
| onic** | *Event |                     |                             |
|        | Ef     |                     |                             |
|        | fect** |                     |                             |
+--------+--------+---------------------+-----------------------------+
| DG     | A      | Bias reduced by     | Represents powered-off side |
| TM1256 | ltered | approximately one   | of GTM.                     |
|        |        | count               |                             |
|        |        |                     | Not required for            |
|        |        |                     | operations.                 |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Altered to new      | Not required for operations |
| IBTEMP | ltered | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| M_     | A      | Altered to new      | Not required for operations |
| OBTEMP | ltered | pattern             |                             |
+--------+--------+---------------------+-----------------------------+
| R      | Biased | Reading             | Thruster Catalyst Bed       |
| RCBnTP |        | Additionally Biased | Temperatures continue to    |
|        |        | By Average of +5° C | operate normally with net   |
| (n=1   |        |                     | positive bias noted         |
| to 12) |        |                     |                             |
+--------+--------+---------------------+-----------------------------+

#### GTM Upset #10

  -------------- ---------- ---------------------- -----------------------------
  **Mnemonic**   **Event    **Comment**            **Status**
                 Effect**                          

  M_IBTEMP       Altered    Altered to new pattern Not required for operations
  -------------- ---------- ---------------------- -----------------------------

#### GTM Upset #11: No Apparent Damage

#### GTM Upset #12: No Apparent Damage 

**Glossary**

  -------------- --------------- ---------------------------------------------
  **Mnemonic**   **Telemetry     **Description**
                 Type**          

  H_TH1          Passive Analog  HYDRA Instrument DDEIS 1 Sensor Temperature

  H_TH2          Passive Analog  HYDRA Instrument DDEIS 2 Sensor Temperature

  H_TPPA1        Passive Analog  HYDRA Instrument PPA 1 Sensor Temperature

  H_TPPA2        Passive Analog  HYDRA Instrument PPA 2 Sensor Temperature

  M_ELTEMP       Passive Analog  MFE Instrument Electronics Box Temperature

  M_IBTEMP       Passive Analog  MFE Instrument Inboard Sensor Temperature

  M_OBTEMP       Passive Analog  MFE Instrument Outboard Sensor Temperature

  ISIESTEMP      Passive Analog  CEPPAD Instrument IES Sensor Temperature

  NX2INTTP       Active Analog   Transponder 2 Internal Temperature

  NX1PWLVL       Active Analog   Transponder 1 Power Converter Voltage,
                                 Telemetry Range 0 to 29.6 Volts

  NX2PWLVL       Active Analog   Transponder 2 Power Converter Voltage,
                                 Telemetry Range 0 to 29.6 Volts

  NS2PWLVL       Active Analog   SSPA 2 Power Level, Telemetry Range 0 to 30.6
                                 Watts

  DGTM15V        Active Analog   GTM Side-1 +5 Volt Supply, Telemetry Range 0
                                 to 7.37 V

  DGTM110V       Active Analog   GTM Side-1 +10 Volt Supply, Telemetry Range 0
                                 to 11.2 V

  DGTM1128       Active Analog   GTM Side-1 1.28 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM1256       Active Analog   GTM Side-1 2.56 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM1384       Active Analog   GTM Side-1 3.84 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM1512       Active Analog   GTM Side-1 5.12 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM25V        Active Analog   GTM Side-2 +5 Volt Supply, Telemetry Range 0
                                 to 7.37 V

  DGTM210V       Active Analog   GTM Side-2 +10 Volt Supply, Telemetry Range 0
                                 to 11.2 V

  DGTM2128       Active Analog   GTM Side-2 1.28 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM2256       Active Analog   GTM Side-2 2.56 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM2384       Active Analog   GTM Side-2 3.84 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  DGTM2512       Active Analog   GTM Side-2 5.12 Calibrated Voltage, Telemetry
                                 Range 0.01 to 5.11 V

  GMTRBI         Active Analog   DPM Side-2 Motor Current, Telemetry Range 0
                                 to 1020 mA

  RRCBnTP        Low-Level       REA Thruster Catalyst Bed Temperature, n = 1
                 Active Analog   through 12
  -------------- --------------- ---------------------------------------------

All affected mnemonics are 8-bit analog parameters

The eight science instrument temperatures are known to share common
multiplexer (mux) chips on analog telemetry board A4 in the GTM. These
parameters use chips U35/U36 for GTM Side 1, and U48/U49 for GTM Side 2.
U36 (or U49, depending on the GTM side powered) is used to route a 0.5
mA current source to the thermistor of interest, and U35 (or U48) passes
the generated voltage to the A/D converter in the GTM. The mux chips in
the GTM are *Harris HI-508A CMOS Analog Multiplexers*.

Mux chips and analog telemetry boards used by the other telemetry
parameters are not known.

**Definitions:**

Passive Analog: Passive analog telemetry, primarily thermistors, in the
range of 0 Ω to 10.2 kΩ. Converted to analog voltages, ready to
digitize, by routing a 0.5 mA current source through the transducer.

Active Analog: Active analog voltage readings, in the range of 0 V to
5.12 V, digitized in the GTM

Low-Level Active Analog: Low-level analog voltage readings from
thermocouples in the range of 0 mV to 32 mV