What impact do clouds have on Earth’s climate? This is one of the most pressing scientific questions of our time. One way NASA is working to answer that question, among others, is by launching the latest in a long line of successful spaceflight instruments, CERES FM6. The instrument measures reflected sunlight and thermal radiation emitted by the Earth.
CERES FM6, or Clouds and Earth’s Radiant Energy System Flight Model 6, is a three-channel radiometer that measures both solar-reflected and Earth-emitted radiation from the top of the atmosphere to the Earth’s surface. CERES measures radiances in three broadband channels: a shortwave channel, a longwave channel, and a total channel.
There are currently six CERES instruments on satellites orbiting Earth and taking data. CERES is a key component of the Earth Observing System (EOS), Suomi National Polar-orbiting Partnership (S-NPP) observatory, and NOAA-20 observatories. The first CERES instrument flew on the Tropical Rainfall Measuring Mission (TRMM) in 1997. The instruments were launched on EOS Terra in 1999, Aqua in 2002, Soumi NPP in 2011 and most recently on NOAA-20 in 2017.
CERES helps provide measurements of the spatial and temporal distribution of Earth’s Radiation Budget (ERB) components. This further develops understanding of the links between the ERB and the proprieties of atmosphere and surface that define it.
Earth’s climate system tries to balance radiant energy from the Sun that reaches the Earth with the energy that is emitted from Earth back to space. Measurements from CERES help scientists understand the links between the Earth’s incoming and outgoing energy and the properties of the atmosphere that affect that energy.
The observations from CERES FM6 help measure the effect of clouds on the energy balance, which strongly influences both weather and climate. CERES allows scientists to validate models that calculate the effect of clouds in driving planetary heating or cooling. CERES’ global observations provide data for improving seasonal climate forecasts, including cloud and radiative aspects of large-scale climate events like El Niño and La Niña.
CERES also determines cloud properties including the amount, height, thickness, particle size and phase of clouds using simultaneous measurements by other Earth Observing System (EOS), and Joint Polar Satellite System (JPSS) instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometric Suite (VIIRS). Analyses using CERES data, build upon the foundation laid by previous missions such as NASA Langley’s Earth Radiation Budget Experiment (ERBE), leading to a better understanding of the role of clouds and the energy cycle in global climate change. These measurements are critical for understanding cloud-radiation climate change and improving the prediction of global warming using climate models.
CERES data can also be used for assessing the radiative effects and climatic impact of natural disasters like volcanic eruptions, major floods and droughts. The long-term data will provide a basis for scientific understanding of cloud and climate feedback that determines climate variations and trends.
The CERES instruments were built by TRW in Redondo Beach, California (now Northrop Grumman Aerospace Systems) and managed by NASA’s Langley Research Center in Hampton, Virginia. The international CERES science team includes scientists from NASA, NOAA, U.S. universities, France, and Belgium. The team blends expertise and guides the definition of the CERES instrument and science studies.
The NOAA-20 spacecraft, carrying the CERES instrument (FM-6), was launched from Vandenberg AFB, CA on November 18, 2017. It extends the measurement series initiated with Earth Observing System (EOS) Terra, Aqua, and Suomi-NPP missions.
For information on JPSS Mission: JPSS Mission
CERES is a key component of Earth Observing System (EOS) and Suomi National Polar-orbiting Partnership (S-NPP) observatory. The first CERES instrument (PFM) flew on TRMM, four instruments are currently operating on the EOS Terra (FM1 and FM2) and Aqua (FM3 and FM4) platforms, and FM5 was launched on the S-NPP platform on October 28, 2011. CERES measures radiances in three broadband channels: a shortwave channel (0.3 — 5 µm), a total channel (0.3 — 200 µm), and an infrared window channel (8 — 12 µm).
The last data processed from the PFM instrument aboard TRMM was March 2000; no additional data are expected. Until June 2005, one instrument on each EOS platform operated in a fixed azimuth scanning mode and the other operated in a rotating azimuth scanning mode; now all are typically operating in the fixed azimuth scanning mode. The S-NPP platform carries the FM5 instrument, which operates in the fixed azimuth scanning mode though it can operate in a rotating azimuth scanning mode.
CERES climate data records involve an unprecedented level of data fusion: CERES measurements are combined with imager data (e.g., MODIS on Terra and Aqua, VIIRS on S-NPP), 4-D weather assimilation data, microwave sea-ice observations, and measurements from five geostationary satellites to produce climate-quality radiative fluxes at the top-of-atmosphere, within the atmosphere and at the surface, together with the associated cloud and aerosol properties.
CERES is a Principal Investigator instrument provided by NASA and managed by NASA’s Langley Research Center (LaRC) in Hampton, Virginia. The instrument was built by TRW in Redondo Beach, California. The CERES Team Leader is Norman Loeb.
The S-NPP spacecraft, carrying the CERES instrument (FM-5), was launched from Vandenberg AFB, CA on October 28, 2011. It extends the measurement series initiated with Earth Observing System (EOS) Terra and Aqua missions.
For information on S-NPP Mission: S-NPP Mission
These pictures show examples of the first measurements that the CERES instrument on the S-NPP satellite have made. We use data products such as these to validate the accuracy of our Earth energy estimates. As we gain confidence in the proper operation of the instrument and the data interpretation algorithms, the science data products will be archived at the Atmospheric Science Data Center.
Contributions to these pages are welcome.
We are pleased to announce that the CERES FM-5 main and MAM covers have opened successfully. Earth viewing science observations began January 26, 2012 at 17:09:13 GMT. All instrument operations are nominal. The attached files are our the First Light images (full 24-h period of data collection). Read NASA’s featured article here.
This image is from the first test scans of Langley’s Clouds and the Earth’s Radiant Energy System (CERES) instrument aboard a NASA Earth-observing satellite launched October 28, 2011 from Vandenberg Air Force Base in California. The CERES instrument targeted the Baltimore-Washington area as the satellite it is aboard passed over the region in the course of its polar orbit. The scans are to make sure planning tools and orbital predictions are accurate. The scans are used for field missions and for ground truth validation purposes. Read the entire article here.
Aqua carries two CERES instruments, the fourth and fifth CERES to fly in space. The first CERES was launched in November 1997 on board the Tropical Rainfall Measuring Mission (TRMM). satellite, and the next two CERES were launched in December 1999 on Terra. The TRMM and Terra CERES have obtained levels of accuracy never before achieved for comprehensive Earth radiation-budget measurements. All the CERES instruments have the capability of operating in either of two scanning modes: fixed azimuth plane scanning, where the scan lines are perpendicular to the path of the satellite, and rotating azimuth plane scanning, where the scan lines are at wide range of angles with respect to the satellite’s path. The paired CERES on Terra and on Aqua provide both of those missions with the possibility of coincident fixed azimuth plane scanning from one CERES and rotating azimuth plane scanning from the other CERES, enhancing the quality of the final products.
CERES is a Principal Investigator instrument provided by NASA and managed by NASA’s Langley Research Center (LaRC) in Hampton, Virginia. The instrument was built by TRW in Redondo Beach, California.
The Aqua spacecraft, carrying two CERES instruments (FM-3 and FM-4), was launched from Vandenberg AFB, CA on May 4, 2002 at 09:55 Universal Time. The links below will list key operations for the two CERES instruments on Aqua, beginning at launch.
NASA’s latest Earth Observing System satellite – Aqua – is dedicated to advancing our understanding of Earth’s water cycle.Launched on May 4, 2002, Aqua has successfully completed its checkout period and is fully operational. Using multiple instruments,Aqua data and images are crucial toward improving our knowledge of global climate change.
The clouds and the Earth’s Radiant Energy System (CERES) instrument is one of six on board the Aqua satellite. CERES detects the amount ofoutgoing heat and reflected sunlight leaving the planet. A detailed understanding of how clouds affect the energy balance is essential forbetter climate change predictions.
These Aqua images show CERES measurements over the United States and the Gulf of Mexico from October 1, 2002. Visible are Hurricane Liliat the center of the image and tropical storm Kyle located to the upper right. Lili developed into a major category 4 hurricane and madeland fall over the coast of Louisiana two days later. Both of these tropical cloud systems have a tendency to cool the Earth by reflectinga large amount of sunlight (white and green areas in the left image) back to space. At the same time, these tropical cloud systems havecountering tendency to warm the Earth by reducing the amount of outgoing heat lost to space (blue and white areas in the right image).Without these tropical cloud systems, the Earth would lose a large amount of heat to space as seen by the surrounding clear-sky regions (red and yellow areas in the right image). The key to unlocking the mysteries of climate and climate changes is understanding the Earth’sdelicate energy balance between reflected sunlight and outgoing heat, and how this balance is affected by the presence of different cloud systems.
Aqua is part of NASA’s Earth Science Enterprise, a long-term research effort dedicated to understanding and protecting our home planet.Through the study of Earth, NASA will help provide sound science to policy and economic decision makers so as to better life here, whiledeveloping the technologies needed to explore the universe and search for life beyond our home planet.
NASA TV VIDEO-FILE FOR JULY 29, 2002
ITEM 1 – AQUA/CERES Instrument First Light Images Over the U.S. – GSFC
NASA’s latest Earth Observing System (EOS) satellite, Aqua, is dedicated to advancing our understanding of Earth’s water cycle. Launched on May 4, Aqua has successfully completed its checkout period and is fully operational. Using multiple instruments, Aqua data and images are crucial toward improving our knowledge of global climate change.
The Clouds and the Earth’s Radiant Energy System (CERES) instrument is one of six on board the Aqua satellite. CERES detects the amount of outgoing heat and reflected sunlight leaving the planet. A detailed understanding of how clouds affect the energy balance is essential for better climate change predictions.
These Aqua images show CERES measurements over the United States from June 22, 2002. Clear ocean regions, shown in dark blue on the left image, reflect the least amount of sunlight back to space. Clear land areas, shown in lighter blue, reflect more solar energy. Clouds and snow-covered surfaces, shown in white and green, reflect the greatest amounts of sunlight back to space. Clear warm regions, shown in yellow over much of the western U.S. on the right image, emit the most heat. High, cold clouds, shown in blue and white, significantly reduce the amount of heat lost to space.
Aqua is part of NASA’s Earth Science Enterprise, a long-term research effort dedicated to understanding and protecting our home planet. Through the study of Earth, NASA will help to provide sound science to policy and economic decision makers so as to better life here, while developing the technologies needed to explore the universe and search for life beyond our home planet.
These images represent the first 24 hours of high-rate science data collection from the 2 CERES instruments on Aqua. The sensor scan head remained stowed, staring at internal instrument structure which provides a stable source so characteristic noise patterns of the sensors may be quantified. CERES collects 660 samples (abscissa) in a data packet, representing a 6.6 second packet length, the ordinate represents raw digital output of the sensors. A single count is equivalent to roughly 0.5 W/m2 TOA flux. Globally averaged Outgoing Longwave Radiation and reflected Solar radiation values are typically 240 W/m2 and 100 W/m2 respectively. Patterns in the data are correlated with onboard microprocessor activities. There is no measurable difference from identical measurements made during ground calibrations prior to launch.
CERES consists of two broadband scanning radiometers that measure the Earth’s radiation balance and provide cloud property estimates to assess their role in radiative fluxes from the surface to the top of the atmosphere.
CERES is a broadband scanning thermistor bolometer package with extremely high radiometric measurement precision and accuracy. The Terra Mission spacecraft carries two identical instruments: one operates in a cross-track scan mode and the other in a biaxial scan mode. The CERES Terra cross-track scanning data greatly extends the CERES data from the Tropical Rainfall Measuring Mission (TRMM) to achieve complete global measurements by adding mid-latitude and polar observations. TRMM data is restricted by its orbit to roughly cover 40S to 40N. Terra crosstrack data also adds observations at different times of day than TRMM (and later Aqua) in order to increase the accuracy of measuring the large diurnal cycle of the radiation fields from day to night.
Finally, the CERES Terra biaxial scan mode provides new observations of the angular radiation fields in order to greatly improve the accuracy of the final fluxes of solar and thermal energy used to derive the Earth’s radiation balance.
Each CERES instrument has three channels–a short-wave channel for measuring reflected sunlight, a longwave channel for measuring Earth-emitted thermal radiation in the 8-12 µm “window” region, and a total channel for total radiation. Onboard calibration hardware includes a solar diffuser, a tungsten lamp system with a stability monitor, and a pair of blackbody sources. Cold space and internal calibration looks are performed during each normal Earth scan.
CERES is a Principal Investigator instrument provided by NASA and managed by NASA’s Langley Research Center (LaRC) in Hampton, Virginia. The instrument was built by TRW in Redondo Beach, California. The CERES Team Leader is Norman Loeb. More information may be obtained on the CERES Home Page.
The Terra spacecraft, carrying two CERES instruments (FM-1 and FM-2), was launched from Vandenberg AFB, CA on December 18, 1999 at 18:57 Universal Time. Terra, originally designated as EOS-AM, is the flagship for the Earth Observing System (EOS). The links below list key operations for the two CERES instruments on Terra, beginning at launch.
For information on Terra Mission: Terra Mission
These pictures show examples of the first measurements that the CERES instruments on the Terra satellite have made. We use data products such as these to validate the accuracy of our Earth energy estimates. As we gain confidence in the proper operation of the instrument and the data interpretation algorithms, the science data products will be archived at theAtmospheric Science Data Center.
This image shows reflected solar radiance emerging from the top of the atmosphere, as measured by the CERES Flight Model 1 (FM1) instrument on the Terra spacecraft. These preliminary (unvalidated) data show twenty four hours of measurements covering the entire Earth from North Pole to South Pole. Reflected solar radiance (or brightness) is a quantity describing how much light energy is moving in a particular direction, in this case the direction between a position on the Earth and the Terra spacecraft. Terra is moving from north to south in the individual orbital swaths that are sometimes visible on close examination of this image. Swath-related features appear most noticeable over the Eastern Pacific, which is just west of South America. There are four features spaced between the left edge of the image and South America that are probably related to the geometry of the scan pattern, where the east side of each swath is being observed at about 11:45 a.m., local solar time, while the west side of each swath is observed at about 9:45 a.m. Where there are no clouds over the oceans, this image is very dark — as we can easily see in the Carribbean or the Indian Ocean between Saudia Arabia and the Indian subcontinent. Where the ocean part of the image is lighter, there are clouds reflecting sunlight back to the CERES instrument. The tropical oceans near the Equator show intense thunderstorms. These are particularly visible between Africa and Australia, where the storms form part of the Intertropical Convergence Zone (ITCZ). Air ascends in the ITCZ and descends on the midlatitudes, where it makes it harder to form clouds. Further away from the Equator, we can see large storms, such as the cold front west of the Appalachians and the storm over the Northwest Pacific Coast of the United States. The southern oceans show particularly striking patterns associated with huge storm systems circling the Antarctic continent. Land reflects more sunlight than the oceans do. The Sahara Desert, in the center of this image, is one of the most reflective large land targets in the world, along with the Saudi Arabian Peninsula. Other land areas of the Earth are darker — with the rain forests of South America and Africa being almost as dark as the oceans. In this image, the rain forests are covered by clouds, so these naturally dark regions do reflect a large amount of sunlight. While this image is a beautiful reminder of the relationship between clouds and radiation, much work remains to be done in quantifying the uncertainty in the measurements. Other instruments on Terra will also contribute to determining the properties of the clouds, the state of the vegetation on the land, and the mixture of biological and chemical activities in the oceans.
This image shows the reflected solar flux emerging from the top of the atmosphere. The data are taken from an entire day of observations from the CERES Flight Model 1 (FM1) instrument on the Terra spacecraft. The quantity plotted is “reflected solar flux,” which not only involves instrument calibration and geolocation, but also removes the angular dependence of the upwelling radiance field. Thus, these data are Level 2 data, which means that CERES has been able to get a reasonable “engineering” calculation of derived physical fields within a few days of opening its covers. The data shown come from Saturday, February 26, 2000, the first full day of FM1 scanning. The latitude where the Sun is overhead is slightly below eight degrees south of this day. The upper portion of the globe, from about 80 degrees north to the North Pole, receives no sunlight on this day and reflects none. The CERES instrument sees an entire swath of the Earth from limb-to-limb as the satellite passes from North to South. The short black arcs that are regularly spaced near the Equator mark the edges of the scan swaths. Although the CERES instrument actually covers the Earth from one swath to the next, the image was made without taking the expansion of the instrument field-of-view into account. Just to the left of the center of the image, we can see South America. The North American continent is off to the northwest, where it is obscured by a cold front east of the Appalachians and a storm striking the Northwest Pacific Coast. Africa, particularly the Sahara Desert, and Saudi Arabia are clearly visible to the right of center in this image. The Sahara is obscured to some extent because of clouds. Saudi Arabia is not obscured, so we can see the bright sands of the desert contrast with the dark ocean at the southern edge of the Arabian Peninsula. Most of the patterns visible away from the Equator are large storm systems, where clouds reflect a large fraction of the incident sunlight. To the right of center, we can see much of the Indian subcontinent, although a large and very bright storm over the Himalayas extends to obscure the Pacific coast of China. Between India and Australia (visible just below the Equator on the lower right of the image), we can see a series of large thunderstorms that form the clouds in the Intertropical Convergence Zone (ITCZ). Far to the south, we can also see the high reflectivity of the Antarctic snow and ice emerge from the mixture of the cloudy and clear areas over the Southern Atlantic and Pacific.
Emitted Longwave Flux – 2/26/2000 – This image shows the energy being lost from the Earth and the atmosphere by thermal emission. This process, familiar to most of us as the heat radiated by electric stove elements, involves light with wavelengths invisible to the eye. Again, these data are Level 2 data from Saturday, February 26, 2000. In this image, blue values come from cold scenes with low thermal emission, while red/magenta values come from hot ones with high emission. As we might expect, the colder regions near the poles are blue, while the much warmer tropics are red. Near the center of the image, in red, we can see the Saudi Peninsula standing in contrast with the warm waters of the Indian Ocean, which appear a light shade. The land is hotter than the ocean, as we might expect from having the Sun shining on the Earth under clear skies at about 10:45 a.m. local time. Surprisingly, the Sahara Desert appears to have fairly extensive cloud cover, particularly near the Mediterranean. Along the Equator from the Amazon Basin in South America, across the Atlantic to the Congo Basin, and then over the Indian Ocean, we can see the tops of very high, thunderstorms in the Intertropical Convergence Zone. These appear in the image as very dark blue or black features that we typically associate with huge cirrus anvils. The temperature of the atmosphere declines with altitude, so that the tops of these tropical thunderstorms are actually colder than the surface of the Earth at the wintertime pole. The red/magenta features in this image are primarily clear areas, where we see through to the Earth’s surface without much impediment from clouds. In addition to the Indian Ocean, we might expect central Mexico and a large area of the Western Pacific to be relatively cloud free. The prominent green and blue features away from the Equator are typically large storm systems. Over the United States, we can see a frontal system west of the Appalachians that brought a moderate amount of rain to the Ohio Valley and the Northeast. We can also see a massive storm system depositing rain (and snow) on the Northwest Pacific Coast.
This picture shows Terra and TRMM data as the two satellites cross each other’s path (also see image below). The black dots and red circles represent Terra and TRMM data, respectively. The 70 black dots inside red circles correspond to overlapping Terra and TRMM measurements. To compare their data directly, the two instruments must look at their target from the same viewpoint. The 17 blue dots show the matched Terra and TRMM measurements of radiation emitted by the Earth (LW) while the 7 yellow dots are matched measurements of reflected solar radiation (SW). The difference between Terra and TRMM is on the order of 1% or less, but the variability is large (2.5-5%). To improve the confidence in our comparisons we must collect data from many such overlaps.
On March 3, 2000, the CERES team began joint operations with TRMM and Terra to compare the performance of the instruments on each satellite. This picture shows a comparison on March 4 with the Terra satellite moving north to south and the TRMM satellite moving west to east at nearly the same time. At the orbit crossing point, we rotate the scan plane of CERES FM1 on Terra to match the scan plane of TRMM. This event is over the northern Pacific and shows a bright cloud (in red) at the crossing point. Many such crossings are needed to gain confidence in the accuracy of the measurements.
CERES Terra FM1, 2/29/00, Hour 2, CERES Total Filtered Radiances Upward. Instrument is in the crosstrack, normal-earth scanning configuration. The spacecraft is descending over the Phillipines. Note the overlapping biaxial data from the corresponding FM2 data plot.
CERES Terra FM2, 2/29/00, Hour 2, CERES Total Filtered Radiances Upward. Instrument is in the biaxial, normal- earth scanning configuration. The spacecraft is descending over the Phillipines. Note the overlapping crosstrack data from the corresponding FM1 data plot.
CERES Terra FM2 – 2/27/2000 – CERES Total Filtered Radiances Upwards for Data Range: 01:58:44 – 02:53:57. Instrument is in the crosstrack, normal-earth scanning configuration. The spacecraft is descending over the Phillipines. The sun viewing zenith can be seen by the horizontal line just below the equator and the line runs east to west during this period.
CERES Terra FM1 – 2/26/2000 – CERES Total Filtered Radiances Upwards for Data Range: 01:15:04 – 02:44:57. Instrument is in the crosstrack, normal-earth scanning configuration and the period is within one hour of commencing science operations after the covers were opened. The spacecraft is descending over the Phillipines. The sun viewing zenith can be seen by the horizontal line just below the equator and the line runs east to west during this period.
The Clouds and the Earth’s Radiant Energy System (CERES) experiment will allow researchers to study the Earth’s atmosphere from space. Measurements from CERES will be used to help us understand the complicated balance between the energy from the Sun which the Earth absorbs either at the surface or in the atmosphere, and the energy which is radiated from the Earth to space. If this balance changes, so will our climate (this is what happened, for example, in the Ice Ages).
In particular, CERES will help us understand how clouds influence the Earth’s energy balance and the role of clouds in regulating our climate. With this increased understanding, scientists will be able to improve long term climate forecasting — not just what the weather will be in the next few days, but will there be long term changes in the coming years: hotter summers, colder winters, and stronger storms — and will be able to investigate on-going natural and human-induced global climate change.
Because characterizing clouds is the biggest unknown in current climate prediction models, the type of measurements that CERES will provide have become one of the top scientific priorities in the U.S. Global Change Research Program.
With the launch of the first CERES instrument in November 1997 on the Tropical Rainfall Measuring Mission, we will begin to obtain this critical information. Additional flights will occur in 1998 and 2000. CERES data will become part of the planetary “health checkup” of the Earth system that will provide a baseline for measuring any future changes in the Earth’s climate system.
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 a monthly account of the CERES instrument mission.
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:
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.
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.
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.
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.
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.
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.
The instrument operated in the crosstrack mode commanded entirely by stored spacecraft commands. An internal calibration was performed during the day.
The instrument was operated in the biaxial mode with all solar avoidance commanding being issued by stored spacecraft commands.
The instrument was operated in the crosstrack mode.
The CERES Proto-Flight Model (PFM) instrument aboard the Tropical Rainfall Measuring Mission (TRMM) exceeded a yellow high limit for the Data Acquisition Assembly (DAA) +15 volt measurement on August 18, 1998. Upon review of instrument data it was noted the +15 volt level began increasing on July 31, 1998. The trend for the maximum voltage seen during a 24 hour period has been gradually upward since July 31st with an amplitude peak reaching approximately 16.9 volts on September 1, 1998. Due to overvoltage concerns for electronic parts downstream of the converter, the CERES instrument’s operational power has been removed. LaRC, TRW, and the TRMM Flight Operations Team continue to examine the CERES instrument and spacecraft data for an explanation and resolution to the anomaly.
We have experienced our first hardware glitch on the otherwise fantastic performance of the CERES instruments. A brief summary of what we know so far is given below courtesy of Jack Cooper and Greg Stover:
During the evening Greg Stover, Deputy Manager for CERES Project, was paged by the TRMM FOT with the news that the CERES instrument DAA +15 V had reached a value of 16.5 Volts. This was seen during the real time contact that started at 244:03:36:00 UT. This was the pass during which the SWICS was turned OFF. During the next pass (started at 244:04:25) Greg instructed the TRMM FOT to SAFE the CERES instrument and turn OFF the operational power. At the beginning of the pass the voltage was 16.64 Volts. TRW and LaRC CERES Project Office will examine the latest data and decide what course of action to take. At this time it is not clear as to how we will proceed with the Deep Space Calibration.
PROTO-FLIGHT MODEL CONVERTER TIGER TEAM CONTINUES INVESTIGATION —
Yesterday at 8pm EST the CERES instrument was powered back up. Greg Stover of the CERES instrument team just called from GSFC where a joint LaRC/GSFC team are monitoring the instrument operations and real-time data as the instrument warms back up to operational temperatures.
Here is the latest after almost 2 days of operation:
The Good News:
Now the Bad News:
What are the Candidates to Explain the Problem?
What about the other CERES instruments for EOS-AM and PM?
What about overlap of the CERES data record with SCARAB and the EOS-AM CERES instruments?
What about the upcoming meteor shower in mid-November?
EFFORT ON CONVERTER ANOMALY DETERMINATION CONTINUES —
After review of information concerning the Leonid meteor storm composition, and of the analysis provided concerning the storm’s direction with respect to the CERES instrument, a decision has been made to leave the CERES instrument in its current state. At this time, the instrument is at an azimuth position of 216 degrees, the elevation head is stowed, and all operational power is removed.
Furthermore, it has also been concluded it is not necessary to conduct special test sequences for the purposes of collecting additional engineering data. This data will be collected coincident with the periods when the instrument is operated specifically to fulfill science team objectives. Therefore future operations will primarily be scheduled based on science collection periods with consideration for safe instrument operations.
At this time the CERES science team is reviewing the next time when science data will be collected. It is currently anticipated this period of CERES operations will occur in December.
Here is an update of our current understanding of the impact of the voltage converter anomaly on the CERES instrument on TRMM.
For information on TRMM Mission: TRMM Mission
These pictures show examples of the first measurements that CERES has made. We use data products such as these to validate the accuracy of our Earth energy estimates. As we gain confidence in the proper operation of the instrument and the data interpretation algorithms, the science data products will be archived at the Atmospheric Science Data Center
ERBE-Like Daily Processing
