Skip to main content
CERES Home Page CERES Home Page

CERES TRMM - What's Happening

The Tropical Measuring Mission (TRMM) spacecraft, carrying the first Clouds and the Earth's Radiant Energy (CERES) instrument, launched from Japan on November 28, 1997 (Thanksgiving Day in the United States). Following is an account of the first 14 days of the CERES instrument mission:

Gold bullet Launch through
Day 5

November 27 - December 1, 1997

The instrument was launched with survival power applied and was operated in this mode until day six. All temperatures were noted to be within expected ranges.

Gold bullet Day 6 December 2, 1997

CERES operational power was applied for the first time. The memory patches for the instrument were uploaded and the instrument was allowed to "warm up" before further operations. The instrument sensor temperatures were observed in the expected operational range after approximately 15 minutes. Other temperatures were observed during real time passes and were within the ranges for commencement of operations in approximately three orbits

During the day, the instrument was commanded to uncage the azimuth gimbal brake and move to the crosstrack position. Several default parameters were reset in software and a memory dump was performed. The instrument was placed in the safe mode for the remainder of the day. Key parameters of the instrument were monitored during each pass.

It should be noted after application of operational power, the azimuth encoder did not experience the "rollover" that had been seen occasionally during I&T testing.

Gold Bullet Day 7 December 3, 1997

This was the first day in which the azimuth gimbal was rotated through the entire range of motion. The instrument was commanded through several sequences which incrementally moved the azimuth gimbal to the operational position (first commanded to the discrete locations and later allowed to scan between locations). The elevation gimbal was also exercised in the various scan profiles which were used during operations. The functionality of the temperature controller for the science sensors was also verified. At the conclusion of testing, the instrument was placed in the crosstrack mode for the remainder of the day.

Special NOTE: During the day high resolution gimbal data was taken which, after analysis, showed no increase in friction for the azimuth gimbal operations as compared to prelaunch values.

Gold Bullet Day 8 December 4, 1997

The instrument continued to operate primarily in the crosstrack mode. The first internal calibrations were performed in the crosstrack and biaxial modes. All calibration sequences executed as expected. Later analysis of the science data showed the offsets of the shortwave channel matched the offsets measured during ground testing. This is the primary channel calibrated using this sequence.

During this day it was observed the telemetry parameter for the main cover sensor number 1 occasionally oscillated and a bad sensor telemetry point was periodically recorded for sensor status. This type of response had been seen in thermal vacuum testing and is normal during periods of heating and cooling of the main cover. These events were correlated to solar events (sunrise, sunset) and the response to the limited conditions were noted for the Flight Operations Team.

Gold Bullet Day 9 December 5, 1997

The instrument continued to operate primarily in the crosstrack mode. The solar calibration contamination safe, and hold sequences were functionally verified. All temperatures and voltages continued to be within specification.

Gold Bullet Day 10 December 6, 1997

During this day the instrument was operated primarily in the crosstrack mode. During a period of the day the instrument was operated in the biaxial mode and spacecraft stored solar avoidance commanding was verified. This verification occurred during a real time pass.

Gold Bullet Day 11 December 7, 1997

The instrument operated in the crosstrack mode commanded entirely by stored spacecraft commands. An internal calibration was performed during the day.

Gold bullet Day 12 December 8, 1997

The instrument was operated in the biaxial mode with all solar avoidance commanding being issued by stored spacecraft commands.

Gold Bullet Day 13-14 December 9-10, 1997

The instrument was operated in the crosstrack mode.

  Image: NASA Logo NASA Official: Dr. Norman Loeb
Page Curator: Edward Kizer
Page Last Modified: 10/16/2017 11:04:42 EST
Site Last Modified: 11/07/2017 17:18:43 EST