GOES-K UPDATE last upodate 17 November 2009


After launch, GOES-K was located at 105 W longitude for post-launch testing of the instruments during the spring of 1998, and was named GOES-10.

After testing, NOAA-NESDIS shut GOES-10 down in June 1998, planning to keep it as an "on orbit spare" until GOES-8 or GOES-9 failed, which they expected around the year 2000 AD.

However, right after NESDIS shut down GOES-K, GOES-J's (GOES-9's) momentum wheels threatened to fail, so GOES-K was called right back out of storage in on 9 July 1998, for a week of spin-up and a month of orbital drift from 105W to 135W during August 1998 to take over as GOES-WEST.

GOES-10 operated as GOES-WEST until 27 June 2006, and then was taken out of operational service becasue it was running low on station-keeping fuel.

Late in 2006, NOAA moved GOES-10 to 65W to devote dedicated scan time to covering South America, as part of the Global Earth Observation System of Systems (GEOSS). While moving GOES-10, NESDIS took continuous 1-minutes scans of the southern USA.

GOES-10 is out of inclination-keeping fuel, so the satellite no longer stays over the equator. Consequently, imagery has to be reprocessed to make it look like it comes from a geostationary satellite.

In October 2008, the Sounder's filter wheel apparently stopped spinning.

In mid-November 2009, NOAA planed to decommission GOES-10 on December 1, 2009. GOES-10 will be boosted to a disposal orbit and all GOES-10 user services will end on December 1, 2009, at 1230 UTC.

There is a scrapbook of GOES-10 Results on-line.

Special GOES-10 CONUS-scan test by NESDIS, Spring 1998

From mid-March to mid-April 1998, the GOES-10 Imager operated in a nearly continuous CONUS-scan mode, observing central North America every five minutes, 24 hours per day, 7 days per week for 4 weeks, mid-March to mid-April 1998:
One frame was skipped every half hour (at hh:10 and hh:40) for "house keeping" activities like star-sensing. The imager was turned off during local midnights when the satellite orbits through the Earth's shadow.

During the CONUS-scan test, GOES-10 realtime images were posted on the web server at GSFC, and at a NOAA site.

After the test, NOAA put together a report on the results.

Notes from NOAA


  1. mid-October 97 = begin ground systems revision for inverted operation
  2. mid-November 97 = store GOES-10 in ZAP mode
  3. mid-January 98 = remove GOES-10 from ZAP mode
  4. February-March 98 = ground systems testing
  5. March-April 98 = CONUS rapid-scan demonstration
  6. April 98 = begin tests of operational modes
  7. May 98 = complete tests of operational modes, turn over to NOAA
  8. June 98 = NOAA returns GOES-10 to ZAP storage mode
  9. July 98 = NOAA revives GOES-10
  10. August 98 = GOES-10 becomes GOES-WEST at 135W

Brief history of the GOES-K Solar Array

Late in May 1997, the solar array "stuck" after 17 days of successful post-launch operation at geosynchronous orbit in the normal south-pointing orientation.

After two months of analysis and testing, GOES-10 was flipped north-south on July 31, and the north-pointing solar array was commanded to rotate in the opposite direction. Ever since then, GOES-10 has successfully tracked the sun "counterclockwise" 24 hours per day.

Broadcasts of images and the remainder of the post-launch test program from the upside-down GOES-10 satellite required a rewrite of the ground system software by NOAA-NESDIS contractors in late 1997.

So, for the remainder of 1997, the post-launch team tested the on-orbit cold-storage mode known as ZAP (Zero Angular Precession). ZAP mode testing during the first two weeks of November were quite successful, with minor anomalies from the predicted attitude and temperatures.

On 13 January 1998, GOES-10 was taken out of hibernation. There were no significant problems during the the wakeup sequence, and the Imager and Sounder performed satisfactorily during the software shakedown in January and February 1998.

In March-April 1998, the GOES-10 Imager was used to take rapid scans on the United States.

In May 1998, GOES-10 was tuned up and tested for normal operations.

In June 1998, GOES-10 was shut down adn returned to ZAP mode to serve as an on-orbit spare for GOES-EAST or GOES-WEST.

NOAA declines to operate GOES-10 as a "StormSat" to watch for rapidly developing events.

If GOES-10 suddenly loses all power from the solar array, the satellite will have to be de-orbited (pushed a few hundred kilometers higher) before the batteries are exhausted.

Long history of the Sticky Solar Array

GOES-10 went into in safe hold mode on orbit after the solar array slowed down and stopped at 10 pm EDT on May 26, 1997, for no apparent reason. There had been two very brief halts in the rotation during the previous 3 weeks.

On July 16, after weeks of discussion and ground testing, the GOES-10 solar array was driven in the reverse direction, resulting in irregular motion and a snap, so the test was halted. A backlash (snap) is not unusual or harmful for this motor being put into reverse.

On July 23, the solar array was driven 1.5 degrees in the reverse direction, resulting in a pause, then slow motion, and then normal motion for 5 minutes until the scheduled end of the test.

On both July 24 and 25, the solar array was driven 1.5 degrees in the reverse direction, resulting in normal motion for 6 minutes until the scheduled end of each test.

On both July 29, the solar array was driven 15 degrees in the reverse direction, resulting in normal motion during the 60 minute test.

The entire spacecraft was flipped over on July 31st. With the solar array pointing north, the motor is being run "counterclockwise", allowing continuous sun-tracking and full power. Small periodicities in the counter-rotating array suggest some minor gear damage.

On August 8, some visible test images were taken (inverted), with no apparent anomalies.

On August 20, the first infrared data were taken with the Imager and Sounder focal planes cooled down to 104 K, with all systems OK. Sensitivity was within 10% of prelaunch values for all detectors, a typical post-launch condition.

As of mid-November, there have been no further anomalies with the solar array, even during large angle slews to accomodate ZAP mode on-orbit storage.

The engineering analysis of the sticky solar array, issued in January 1998, was unable to conclusively identify the cause of the jam-up.

The GOES-K Launch and Deployment Story (April-May 1997)


A flawless launch occurred on time at 0549Z (0149 EDT) on April 25th. Initial acquisition occurred with Bermuda 4 minutes after launch, and then by the first tracking station (USAF Diego Garcia) slightly early at 06:24:36Z. The second, ESA's Perth, Australia, also occurred a little early at 06:31:40. Post separation MECO 2 vector showed the spacecraft to be only 4.99km off nominal trajectory. An excellent "ride" from the last ATLAS I! A more accurate orbit calculation showed perigee was less than 1 km off of predicts, and apogee was 20km off. After separation the mission continued incredibly smoothly, executing the launch script ahead of schedule. Solar array outer panel was deployed slightly ahead of schedule, with a DOD of 20.6% (GOES-8 was about 26%, GOES-9 about 21%).


AMF1 motor firing occurred on time at 0105Z on April 27th (2151EDT on April 27th), and continued for about 56 minutes. Steady state Main Satellite Thruster (MST) temperatures were lower than on GOES-9 during the burn, but soakback temperatures were similar to GOES-9. Overall it was an incredibly successful, smooth maneuver! Initial orbits showed an orbit only about 1.6% off nominal. Fuel and Oxidizer tanks ran about 4psia over predicted, which contributed to a slightly hotter burn than predicted, but delta-V was only 3.2 m/s higher than planned (0.4%). Post burn data showed an orbit close to initial estimates, with apogee was approximately 42200km and perigee approximately 11000km.


AMF2 was executed on time at 201041Z on April 19th, for 1810 seconds (30.17 minutes). At completion, the burn was another exceptional maneuver, but 31 seconds into the burn we lost all spacecraft TLM data at the prime station, but the thrid backup antenna operating nominally and an abort was avoided with only a 30 second loss of data. Thermal profiles of the flange and valves were very close to the AMF#1 values. The final orbit was quite good, resulting in an inclination about 0.1 deg high, and a slightly high drift rate at 6.7 deg/day. Apogee height was then roughly 42310km, and perigee height roughly 28230km.

AMF 3:

AMF3 was another text book maneuver beginning on time at 1923Z (152308 EDT) on May 1st, and lasting 430 seconds (7.2 minutes) . Motor temperatures were predictably cooler than previous maneuvers, even without a spacecraft re-orientation maneuver to cool the MST prior to the burn. The maneuver was primarily a perigee raising and plane change maneuver, with perigee height being raised to approximately 35590km (about 70km low), and inclination lowered to a nearly perfect at 0.499 deg, with a period of about 26.5 hours.

Apogee Adjust Maneuver (AAM):

The AAM was executed at 1345Z (0945 EDT) on May 3rd . The AAM began only about 5 minutes off of the pre-AMF#1 predicts, another sign of an excellent mission! This burn was a 2 phase burn of 240 seconds, a delay of 54 seconds, and a second fine tuning burn of 28.3 seconds. The AAM slowed GOES-K drift rate and stabilized it near its nominal location of 105W, reduced the super-synchronous apogee to nominal apogee (reduction of about 6000km), and the period became 23.9 hours. GOES-K also became GOES-10!


Magnetometer #1 was turned-on at about 2118Z (1718 EDT) on May 4th, and deployment occurred at 2156Z. SA phase 1 deploy was executed then at 2314Z (1914EDT), again in a picture-perfect operation. After trim tab slewing, a spacecraft yaw reorientation was executed to warm the SA hinges for phase 2 deployment, and then another reorientation was accomplished to cool the inner SA panel to near 20C (from about 76C). Phase 2 of the SA deploy was executed at 00:00Z (2000EDT). Battery DoD reached 26%.


On May 6th, the reaction wheel was commanded on at 2224Z (1824EDT), and then commanded to nominal operating speed at 1938 RPM. MW #1 was commanded on at 2238Z and commanded to operating speed at 5347RPM. Imager initialization was started at 2255Z with a similar startup and scan test sequence as on the Sounder. Solar sail deployment began at 0010Z (2010 EDT), was driven out for about 13.5 minutes, and was terminated automatically by the micro-switch (the first in the GOES-I-M series!). MST isolation and venting of the fuel and ox lines was executed at about 0115Z and contamination avoidance for the instrument mirrors was begun.


The instruments were initialized on May 7th, and the first test images began on May 8th. The data quality in test imagry is excellent, and we're looking forward to official images and navigation start-ups in the next few weeks. The biggest event of the PLT period will be the newly designed Z-Axis Precession (ZAP) on-orbit storage mode testing from June 2nd through 12th.


On orbit, the only problem has been the solar array, which twice stopped tracking the sun for a minute or two and then resumed in mid-May, and the slowed to a stop on May 26th.


The SN05 Imager was launched in good condition on the spacecraft.

Imager History Highlights

The dubious scan motors and some dubious resistors in GOES-K's Imager and Sounder were replaced with more reliable parts late in 1996.

The Imager's optical surfaces were cleaned and checked just before launch to minimize scattered light.


The SN05 Sounder was launched in good condition on the spacecraft.

Sounder History Highlights

When vibration-tested on the spacecraft in the summer of 1995, a side-panel came loose on the SN05 Sounder. The SN05 Sounder was shipped back to ITT in Fort Wayne, Indiana, where it was strengthened and re-tested. It appears that the 1995 vibration tests were too severe, exceeding the expected launch stresses by about 50%.

On-orbit, the GOES-10 Sounder (aka SN05) is delivering brightness temperatures a few degrees colder than the corresponding observations from the GOES-8 and GOES-9 Sounders. The underlying cause for this calibration error is under investigation (mid-1998).

Launch and On-Orbit Storage Plan

GOES-K was launched without a flaw from Cape Canaveral just before 2 am EDT on 25 April 1997.

The launch was slipped one day due to a tornadic storm front passing through central Florida on April 24.

GOES-K spacecraft completed construction and testing at Space Systems/Loral in Palo Alto, California in early 1996, and it was through thermal-vac testing in Boeing's facility in Seattle in mid-1996. GOES-J was shipped to the launch site at Cape Canaveral, Florida on a C5A aircraft on 15 January 1996.

GOES-K was launched, deployed, and tested for 3 months on-orbit at 105W. Then, it was stored "sleeping" on-orbit, facing away from the Sun in what is called the ZAP mode (Z-Axis Precession, one rotation per year relative to the Earth, for storage on-orbit facing steadily away from the Sun). On-orbit storage avoids on-earth storage costs, post-storage testing, and the 12-month delay expected between NOAA's call-up and launch.

Unfortunately, NESDIS does not budget money and manpower to operate a 3-satellite GOES constellation.

Original post-launch schedule

           EVENT                             DATE
Launch GOES-K                           April 25, 1997 (01:49 EDT = 0549 UTC)
   rocket firings, separations,         April 25
   partial deploy solar panel, etc.
Circularize Orbit                       April 25 - May 12
   Apogee Motor Firing #1                 April 26
   Apogee Motor Firing #2                 April 29
   Apogee Motor Firing #3                 May 1
   Apogee Adjust Maneuver                 May 3
GOES-K becomes GOES-10                  May 3
Deployments                             May 4 - May 6
   Magnetic boom                          May 4 
   Solar Array                            May 5
   Magnetic dipole estimation             May 5
   Imager/Sounder initialization          May 6
   Momentum wheels spinup                 May 6
   Solar Sail                             May 6
GOES-10 ready                           May 7 (on orbit, deployments complete)
Instrument scan mirror contam. avoid.   May 4-12
Start-ups and functional tests          May 7-15
Final Orbit Trim                        May 10-12
First official visible image            May 13
Outgassing                              May 5-31
Start-ups and functional tests          May 7-TBD
Imager priority mode interrupt test     TBD
Boresight alignment tests               June 10-13
Storage Mode Test-dynamics phase        June 16-20
First official infrared image           June 21
Storage Mode Test-thermal validation    June 22-26
 Performance Testing                    June 28-August 5
   INR startup-Imager                   June 30-July 3
   INR startup-Sounder                  July 5-7
   INR spec. tests, psuedo-schedules    July 8-26
   NASA Science Testing (interrupts)    July 22-24
   NOAA Science testing                 July 27-August 6
On-orbit Storage preparation            August 11-13
   North/South Maneuver                 August 14
   Ranging/orbit determination          August 10-11
   East/West Maneuver (if needed)       August 10
   Pre-Storage Planning Meetings        August 11
Enter ZAP on-orbit storage              August 12
ZAP Storage                             Up to 2 years from entry
   *INR stands for "Imager Navigation and Registration"
   **ZAP stands for "Z-Axis Precession"
These dates are subject to change based on actual launch date and success of post-launch engineering checkout, and assumption that GOES-8 and GOES-9 are operational.

GOES-K ZAP Mode storage

Date: Tue, 2 Jun 1998 07:10:03 -0400 (EDT)
From: Charles Bengston (cbengsto@csc.com)
Subject: GOES-10 ZAP Mode Activation 
MIME-Version: 1.0

GOES-10 was successfully placed into a Z-axis Precession (ZAP) mode at
approximately 4:00 am this morning (June 7).  This maneuver sequence was
the last major milestone prior to NASA handing over GOES-10 operations to
NOAA, scheduled for June 5. The entire ZAP activation sequence was
executed with no problems.  This sequence returned GOES-10 to ZAP mode
following 4 1/2 months of rigorous ground system and spacecraft
post-launch tests while the in an inverted mode due to the solar array
drive anomaly.  GOES-10 will remain in ZAP mode at a 105 degree longitude
station location until call up by NOAA to replace the existing GOES-8 or
9 operational spacecraft. Below summarizes the key maneuver sequences and
results of the ZAP activiation sequence: 

The GOES-10 spacecraft is currently in a stable spin around the major
principal axis spinning at approximately .75 deg/sec with a Sun coning
angle of approximately .5 degrees. Spacecraft ZAP re-spins are required
when coning angles approach a maximum of 20 degrees.  At this initial
coning angle (based on predictions and the previous ZAP test) a re-spin
may not be required for as much as 60 days. The solar array remains
stopped at the commanded ZAP mode array position. Thermal parameters are
all currently within storage mode limits. Instrument baseplate and 4
mounting panel heaters have been turned on.  Engineers will be closely
monitoring both thermal and dynamics stabilization over the next couple
days.  Some key events and observations that occurred during the
activation were:

    - Instruments were configured for standby mode and the Sounder
    filter wheel was turned off.  Filter wheel spin down time was
    nominal (measured at approximately 100 seconds).

    -  Momentum wheels were spun down and turned-off while spacecraft
    was in pitch earth acquisition mode.

    - Two large angle solar array slews of 82 and 111 degrees in the
    reverse direction were successfully performed.  Solar array
    potentiometer data was nominal throughout both slews with no
    unexpected signatures observed (ADS data not available due to MDL
    transmitter off).  The second slew positioned the solar array
    approximately 3 degrees off the predicted principal axis to 159.2
    degrees.  The 3 degree offset was required to allow for final
    tweeking of the solar array in the reverse only direction to the
    actual measured principal axis.  Final solar array fine adjustments
    will be performed over the next day. 

    - The XRPE temperature temporarily reached 60 degrees C (close to Qual
      temperature) during the second solar array slew due to
      sunlight on the back of the electronics. However, the temperature
      rapidly dropped back to nominal values shortly following the slew

Ranging with the DSN will be conducted over the next couple of days to
determine spacecraft orbit and drift rates.
Reactivation of GOES-10 should take about 14 days, and movement to an operational slot 30 degrees away at a drift rate of 1 degree perday will require another 30 days. (A 45-day delay is a lot less than a 1-year delay to launch and commission a spare satellite stored on the ground.)

GOES-K call-up criteria

NOAA is considering the following GOES-10 call-up assumptions:
a.  GOES-10 to be activated upon failure of either
    the imager, sounder, or a critical, nonredundant control subsystem
    (e.g., lose IMC) on either operational GOES.
b.  Maneuver to operational station from 105W to begin as soon as possible,
    based on satellite operational constraints.
c.  Management (AA NESDIS in concert with AA NWS) to review call-up
    decision at the time of failure to account for all possible contingencies.
In the event of a GOES-8/9 failure, GOES-10 images should be available within a few days while soundings and derived products would be on-line within 4-7 weeks.

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