Minimize DMSP Block 5D-3 Satellite Series

DMSP Block 5D-3 Satellite Series

Spacecraft     Launch    Mission Status     Sensor Complement    Ground Segment    History of DMSP    References

DMSP (Defense Meteorological Satellite Program) is a long-term operational meteorological program of the US DoD (Department of Defense), managed by the USAF and operated by the 6th Satellite Operations Group at Offutt AFB (Air Force Base), Nebraska. The program originated in the early 1960s with the objective to collect and disseminate worldwide cloud cover data on a daily basis (along with oceanographic and solar-geophysical environment parameters). The DMSP system is being used for strategic and tactical weather prediction to aid the US military in planning operations at sea, on land and in the air.

In the early 1960s, the reconnaissance community initiated a program using low-altitude satellites as an interim measure to collect cloud-cover data. The highly classified system, known as Program 417, was to support the operational needs of the Corona satellites, designed to provide photo imagery of the Soviet Union. Corona satellites used conventional film to record their data, and the film canisters were jettisoned and returned to Earth via parachute and recovered by aircraft. The DOD wanted to maximize the usefulness of the film and needed a satellite program to predict cloud cover. Thus began Block 1 of DMSP. The program initially involved a small number of Aerospace scientists and engineers in the Electronics Research and Space Physics Laboratories. Their tasks involved improving elements of the primary sensor and developing secondary sensor concepts as well as general science and technology support. Secondary sensors developed in the laboratories flew on numerous DMSP missions and were, in many ways, precursors of the secondary sensor complement now flying on DMSP.

The first DMSP satellites employed a simple spin-stabilized design. They carried a video camera with a 1.27 cm aperture sensing in the 0.2–5 µm regime and two IR systems—the medium-resolution “C” system with 16 channels from 5 to 30 µm, and the high-resolution radiometer working in the 7–14 µm domain. A set of horizon sensors were also used for attitude control and for triggering the camera shutter each time it turned to face Earth. Through the 1960s and into the 1970s, a total of 34 DMSPs were launched, all flying the simple rudimentary payloads. It was not until the design of the Block 5 satellites that more instrument capability began to emerge.

See more information of the early DMSP program in the last chapter of this file.

Table 1: The early DMSP history 1)

The DMSP Block 5 series experienced several generations of satellites and instruments (see Table 2). The USAF maintains an operational constellation of two near-polar, sun-synchronous satellites. 2)

In the timeframe 1965 to 2006 (F-17 inclusive), a total of 44 DMSP spacecraft have been launched successfully by the USAF, all were built by Lockheed Martin Corporation.

The Block 5B/C satellites launched between 1971 and 1976 offered increased instrument capability. The vidicon camera was replaced by a constant-speed rotary-scan radiometer. Spin stabilization was abandoned; instead, instruments were mounted on a platform that kept a constant angle between the direction of motion and Earth.

OLS (Optical Linescan System): First flown in 1976, the OLS provided global cloud-cover imagery to military weather forecasters. The OLS operated at two resolutions in the visible spectrum: smooth (2.77 km) and fine (0.55 km). Smooth data processing onboard the spacecraft decreased the resolution and data rate by a factor of 25. The visible channel could detect smoke and dust storms—information that can be critical to strategic planning—as well as ice cover. The instrument was unique in being sensitive enough to view clouds by moonlight. The low-light sensing capability could capture city lights and distinguish lights from fires. This feature could support battlefield damage assessment by enabling commanders to compare the light in a specific area before and after a strike. Thermal IR viewing enabled nighttime cloud viewing at a lower resolution than daytime visible fine-mode data, but provided mission planners with critical 24-hour information about cloud cover and weather conditions.

S/C Bus

S/C Series

Launch Date/
Mission End

Sensor Complement

S/C Mass (kg)

Block 5B

F-1

14.10.1971

Also known as Ops-4311 and P35-26

195

F-2

24.3.1972

Also known as Ops-5058

195

F-3

9.11.1972

Also known as Ops-7323

195

F-4

17.8.1973

Also known as Ops-8364

195

F-5

16.3.1974

Also known as Ops-8579

195

F-6

9.8.1974

Also known as Ops-6983

195

Block 5C

F-7

24.5.1975

Also known as Ops-6226

194

F-8

19.2.1976

Also known as Ops-5140; failed to achieve correct orbit

175

Block 5D-1

F-1

11.9.1976 / 17.9.1979

OLS, SSH, SSJ/3, SSB, Contamination Monitor

450

F-2

4.6.1977 / 19.3.1978

OLS, SSH, SSJ/3, SSB, SSB/0, IFM, SSI/E, SSI/P

450

F-3

30.4.1978 / Dec. 1979

OLS, SSH, SSJ/3, SSB, GFE-3R

513

F-4

6.6.1979 / 29.8.1980

OLS, SSH, SSJ/3, SSI/E, SSM/T, SSC, SSD

513

F-5

14.7.1980 (failed)

OLS, SSH-2, SSJ/3, SSI/E, SSB/O, SSR

513

Block 5D-2

F-6

20.12.1982 / 24.8.1987

OLS, SSH-2, SSI/E, SSJ/4, SSB/A

750

F-7

18.12.1983/17.10.1987

OLS, SSM/T, SSI/E, SSJ/4, SSB, SSJ*, SSM

750

F-8

18.6.1987 / 13.8.1991

OLS, SSM/I, SSM/T, SSI/ES, SSJ/4, SSB/X-M

750

F-9

3.2.1988

OLS, SSM/T, SSI/ES, SSJ/4, SSK

750

F-10

1.12.1990 /2. 1995

OLS, SSM/I, SSM/T, SSI/ES, SSJ/4, SSB/X-2

750

F-11

28.11.1991 / 8. 2000

OLS, SSM/I, SSM/T,SSM/T-2,SSJ/4,SSI/ES-2, SSB/X-2

830

F-12

29.8.1994

OLS, SSM/I, SSM/T, SSM/T-2, SSJ/4, SSI/ES-2, SSB/X-2, SSM

830

F-13

24.3.1995

OLS, SSM/I, SSM/T, SSJ/4, SSI/ES-2, SSB/X-2, SSM, SSZ,

750

F-14

4.4.1997

OLS, SSM/I, SSM/T, SSM/T-2, SSJ/4, SSI/ES-2, SSM,

750

Block 5D-3

F-15

12.12.1999

OLS, SSM/I, SSJ/4, SSI/ES-2, SSM-Boom, SSZ

1220

F-16

18.10. 2003

OLS, SSMIS, SSI/ES-3, SSJ5, SSM-Boom, SSULI, SSUSI, SSF,

1220

F-17

04.11.2006

OLS, SSMIS, SSI/ES-3, SSJ5, SSM-Boom, SSULI, SSUSI, SSF,

1220

F-18

18.10.2009

OLS, SSMIS, SSI/ES-3, SSJ5, SSM-Boom, SSULI, SSUSI, SSF,

1220

F-19

03.04.2014

OLS, SSMIS, SSI/ES-3, SSJ5, SSM-Boom, SSULI, SSUSI, SSF,

1220

S-20

Due to no launch funds by
Congress, the S/C was put in a
museum in Decemer 2017.

OLS, SSMIS, SSI/ES-3, SSJ5, SSM-Boom, SSULI, SSUSI, SSF,

1220

Table 2: Chronological overview of DMSP Block 5 series satellites

Nomenclature: The DMSP satellites are known as F-xx after launch. Prior to launch, they are designated by S-xx. The 5D-2 series of satellites encompasses F-6 through F-14, while the 5D-3 series of spacecraft begins with F-15. As polar-orbiting spacecraft, all DMSP satellites are being launched from VAFB (Vandenberg Air Force Base), Vandenberg, CA, USA.




DMSP and NOAA-POES programs merge

For a period of over 30 years, the DMSP program of the US military, with its LEO polar orbiting satellites (830 km altitude), was in fact a full parallel system to the NOAA-POES series, the US civil LEO weather satellite program in polar orbit. 3) 4) 5) 6) 7)

In the fall of 1993, the US National Performance Review (NPR) and the subsequent Presidential Decision Directive/NSTC-2 (May 5, 1994) called on DOC, DoD and NASA, to “converge” the US civil and military operational meteorological satellite programs (POES of NOAA and DMSP of DoD), in order to reduce duplication of effort and to generate cost savings. In October 1994, an Integrated Program Office (IPO), consisting of a team made up of NOAA, NASA and DoD representatives, was established organizationally under NOAA (with the IPO Headquarters located in Silver Spring, MD) with the explicit objective to integrate their separate meteorological programs into a single program that includes: planning, development, management, acquisition, and operations. A tri-agency MOA (Memorandum of Agreement) was signed in May 1995. The merged program received the name of NPOESS (National Polar-orbiting Operational Environmental Satellite System). The IPO is a tri-agency office reporting through NOAA to an Executive Committee of representatives from DOC, DoD and NASA.

In May 1998, the US Air Force Space Command transferred its day-to-day operations of the DMSP spacecraft to NOAA. With this action, NOAA assumed full responsibility for the operation of both the POES and DMSP satellite constellations. NOAA maintains and conducts joint satellite control operations at a collocated operations center where it also conducts operations of NOAA's GOES (Geostationary Operational Environmental Satellite) series (from Suitland, MD).

The DoD DMSP program and the POES program convergence takes place in two phases.

• First phase: Starting in May 1998, all DMSP satellite operational command and control functions of AFSPC (Air Force Space Command) were transferred to a tri-agency Integrated Program Office (IPO) established within NOAA. NOAA was given the sole responsibility of operating both satellites programs, POES and DMSP (from NESDIS, Suitland, MD).

• During the second phase, the IPO will launch and operate the new NPOESS satellites (starting in 2009) that will satisfy both the DoD and Department of Commerce (DOC/NOAA) requirements.


DMSP and NOAA polar programs separate again :

In Feb. 2010, the NPOESS (National Polar-orbiting Environmental Satellite System) tri-agency program was terminated by the US government due to severe cost overruns and program delays. The NPOESS program was a joint DoD/NOAA/NASA endeavor that tried to integrate the capabilities and infrastructure of the NOAA POES (Polar-Orbiting Environmental Satellite) program, the DoD DMSP (Defense Meteorological Satellite Program), and NASA’s long-term continuous climate record collection. - The President's FY 2011 budget request for NOAA directed the NPOESS program to split into separate NOAA/NASA and DoD programs.

The major challenge of NPOESS was jointly executing the program between three agencies of different size with divergent objectives and different acquisition procedures.

In 2009, an IRT (Independent Review Team) concluded that the current NPOESS program, in the absence of managerial and funding adjustments, has a low probability of success and data continuity is at extreme risk. The Office of Science and Technology, with the Office of Management and Budget and the National Security Council, as well as representatives from each agency, examined various options to increase the probability of success and reduce the risk to data continuity. 8) 9)

NOAA's restructured satellite program, the civilian JPSS (Joint Polar Satellite System), was created in the aftermath of the White House's Feb. 2010 decision to cancel NPOESS. The development of the new JPSS will be managed by NASA/GSFC while the spacecraft will be owned and operated by NOAA. The launch of JPSS-1 is planned for 2016.

NOAA, through NASA as its acquisition agent, will procure the afternoon orbit assets that support its civil weather and climate requirements and DoD will independently procure assets for the morning orbit military mission - referred to as DWSS (Defense Weather Satellite System). Both agencies will continue to share environmental measurements made by the system and support the operations of a shared common ground system.

The Administration decision for the restructured Joint Polar Satellite System will continue the development of critical Earth observing instruments required for improving weather forecasts, climate monitoring, and warning lead times of severe storms. NASA’s role in the restructured program will be modeled after the procurement structure of the successful POES (Polar Operational Environmental Satellite) and GOES (Geostationary Operational Environmental Satellite) programs, where NASA and NOAA have a long and effective partnership. The partner agencies are committed to maintaining collaborations towards the goal of continuity of earth observations from space.

The restructured JPSS (Joint Polar Satellite System) is planned to provide launch readiness capability in FY 2015 and FY 2018 (with launches of JPSS-1 in 2016 and JPSS-2 in 2019, respectively) in order to minimize any potential loss of continuity of data for the afternoon orbit in the event of an on orbit or launch failure of other components in the system. Final readiness dates will not be baselined until all transition activities are completed. 10)

The following restructured concept scenario emerged in 2010:

• NOAA/NASA Joint Polar Satellite System (JPSS) covers the afternoon (13:30 hours) orbit

• JPSS flies an “NPP-like” satellite bus

• DoD covers the early morning (05:30 hours) orbit. A DMSP Follow-on program (beyond DMSP-F-20) is in planning.

• NOAA manages the JPSS ground system.

The European polar weather satellite program of EUMETSAT, namely the MetOp series, is also involved in this new overall scenario through the EPS (EUMETSAT Polar System) agreements (Figure 2).

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Figure 1: Overview of the polar meteorological program evolution in 2010 (image credit: NOAA)

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Figure 2: Scenario of Polar Operational Satellite Programs in 2010 (image credit: NOAA)




Space segment of Block 5D-3 series:

The DMSP satellites were built under a USAF contract by LMSSC (Lockheed Martin Space Systems Company), Sunnyvale, CA. They are three-axis stabilized. Pointing of the satellites is maintained by three orthogonal reaction wheel assemblies. A precision mounting platform provides a pointing accuracy of 0.01º. The spacecraft bus structure was increased in lengthfrom 6.7 m to ~7.3 m and the mass of the satellite rose to ~1220 kg. The spacecraft is separated into four sections or modules: 11) 12)

• A precision mounting platform for sensors and equipment requiring precise alignment

• An equipment support module containing the electronics, reaction wheels, and some meteorological sensors

• A reaction control equipment support structure containing the third-stage rocket motor and supporting the ascent phase reaction control equipment

• A deployable sun-tracking solar array of size 9.29 m2 (10 panels), spacecraft power of 2.2 kW.

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Figure 3: Artist's view of the deployed DMSP 5D-3 spacecraft (image credit: USAF)

The spacecraft stabilization is controlled by a combination flywheel and magnetic control coil system so that sensors are maintained in the desired earth-looking mode. One feature is the precision-pointing accuracy of the primary imager to 0.01º provided by a star sensor and an updated ephemeris navigation system. This allows automatic geographical mapping of the digital imagery to the nearest picture element. The Block 5D-3 series spacecraft have a design life of 5 years.

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Figure 4: Line drawing of the DMSP Block 5D-3 spacecraft

The F-15 and F-16 DMSP satellites are Block 5D-3 series that accommodate larger and more advanced sensor payloads than earlier generations. They also feature a more advanced attitude control system for precision pointing; a more powerful onboard computer with increased memory - allowing greater spacecraft autonomy; a higher rate command link for shorter ground contact times; an increased battery capacity that prolongs the mission duration, and an improved onboard autonomy (60 days). The F-16 spacecraft is in fact the first full Block 5D-3 satellite. Although the F-15 spacecraft features the new Block 5D-3 bus, it is flying the legacy 5D-2 sensor complement.

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Figure 5: Photo of the DMSP Block 5D-3 spacecraft (image credit: LMSSC)

Orbital Parameters of DMSP: 13)
Sun-synchronous orbits, altitude = 811 - 853 km (833 km nominal), inclination = 98.9º, period = 101.6 minutes, there are normally two satellites in operation at any one time (one in a morning and one in a late morning equatorial crossing time).

RF communications: DMSP downlinks mission data stored onboard Stored Mission Data (SMD) once per orbit and has two real-time data transmissions, the Real-time Data Smooth (RDS) and Real Time Data fine (RTD).

Onboard preprocessing of data by the OLS sensor system provides for the various modes of data output. OLS data consists of both visual or Light data (L data) and infrared or Thermal (T data) modes. Infrared Fine resolution data (TF data) can be collected continuously, day and night. Visible fine (LF data) is collected during daytime only. Storage capacity and transmission constraints limit the quantity of fine resolution data (LF or TF) which can be provided in the SDF (Stored Data, Fine) mode. Data smoothing permits global coverage in both the infrared (TS) and visible (LS) spectrum to be stored on the primary tape recorders in the SDS (Stored Data Smoothed) mode.

The data rate is 1.33 MBit/s for SDF (TF or LF) or 2.66 Mbit/s if SDS is interleaved bit-by-bit (TF/LF or TS/LS). The DMSP RTS Mux accepts either data rate and formats Equipment Status Telemetry data with the incoming stored data stream. This 3.072 Mbit/s data stream is then transmitted via a DOMSAT communications satellite link to AFWA (Air Force Weather Agency) and FNMOC (Fleet Numerical Meteorology and Oceanography Center) for processing.

DMSP transmits two S-band downlinks in real-time: Real Time Data (RTD) link containing OLS fine (TF/LS or LF/TS) data; and Real Time Smooth (RDS) data stream containing OLS smooth data. - The F-16 spacecraft features a dedicated S-band for RTD at a frequency of 2222.5 MHz. The date rate of the RDS increases to 88.75 kbit/s unencoded (177.5 kbit/s encoded). Additionally, there is the capability to transmit a UHF RDS transmission at 400.328 MHz and at 400.822 MHz. All DMSP downlinks are encrypted.

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Figure 6: Overview of the F-16/-17 spacecraft sensor complement (image credit: SMC)


Launch: The first of six new DMSP 5D-3 spacecraft was scheduled to be delivered to the Air Force in June 1990. Following the loss of the Space Shuttle Challenger in January 1986, however, all of them were rescheduled for launch atop modified Titan-II intercontinental ballistic missiles.

• The DMSP Block 5D-3-1 was launched on December 12, 1999 from VAFB, CA on a Titan-2 vehicle with 6 Block 5D-2 instruments to test the new satellite bus (F15 on orbit) followed by the F16 satellite on October 18, 2003 with the new 5D-3 payload. Since F16, all 5D-3 satellites have been carrying the same payloads.

• On Nov. 4, 2006, the DMSP F-17 spacecraft was launched on a Delta-4 (EELV) rocket from VAFB (launch mass of 1154 kg).

• On October 18, 2009, the DMSP F-18 spacecraft was launched on an Atlas-5 rocket of ULA from VAFB (launch mass of 1230 kg)

• On April 3, 2014, the DMSP F-19 spacecraft, built by Lockheed Martin, was successfully launched from Vandenberg Air Force Base, CA, on an Atlas-5 vehicle. DMSP-19 joins six other satellites in polar orbit providing weather information.

- Several features on DMSP-19 improve reliability and performance. Those include a more capable power subsystem, an upgraded on-board computer and better battery capacity that extends mission life. Additionally, the satellite carries a new attitude control subsystem and a star tracker. The current Block 5D series also accommodates larger sensor payloads than earlier generations. 14)




Operational status and imagery of the DMSP series:

• March 25 2020: The 2019-2020 winter was warm for most of the middle latitudes of the Northern Hemisphere. Not so in the Arctic, where persistent cold air helped sea ice grow to a larger extent than in several recent years. Still, there was not enough growth during the fall and winter months to bring sea ice back to long-term average levels. 15)

- “So far this year the Arctic sea ice has been more extensive than in most years of the past decade, but it is not close to as extensive as it typically was in the 1980s and 1990s,” said Claire Parkinson, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Recovery to 1980s levels would take thickening of the ice, as well as a greater expanse.”

- Every year, the cap of frozen seawater floating on top of the Arctic Ocean and neighboring seas melts during the spring and summer and grows in the fall and winter. The ice reaches its annual maximum extent sometime between February and April. In 2020, sea ice reached its annual maximum extent on March 5, when satellites observed it spread across 15.05 million km2 (5.81 million square miles).

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Figure 7: This map shows the ice extent—defined as the total area in which the ice concentration is at least 15 percent—at its 2020 maximum. While this maximum was largest since 2013, it remained 590,000 km2 (230,000 square miles) below the average maximum for the 1981-2010 period (yellow line). The lowest maximum extent on record occurred on March 7, 2017, when it measured 14.42 million km2 (5.57 million square miles) - (image credit: NASA Earth Observatory images by Joshua Stevens, using data from the National Snow and Ice Data Center. Story by Kathryn Hansen)

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Figure 8: Arctic sea ice extend in the period September 1, 2019 - March 22, 2020 (image credit: NASA Earth Observatory)

- Jennifer Francis, a scientist from the Woods Hole Research Center who studies the changing Arctic, noted that there can be great variability from year to year because of fluctuations in weather and ocean currents. This year, a strong stratospheric polar vortex helped trap cold air in the Arctic. The same phenomenon left mid-latitudes warmer and generally less snowy than normal.

- “This winter happened to have an upswing in the ice cover, but it’s still well below normal and there’s every reason to expect the downward trend will continue,” Francis said. The downward trend is clear when you chart successive seasonal ups and downs as measured by satellites over four decades: the annual maximums and minimums are generally becoming smaller over time. This change, while seemingly remote and regional, has global consequences.

- What happens in the Arctic doesn’t stay in the Arctic,” Francis said. “Losing so much bright, white ice means the Earth now absorbs much more of the Sun’s energy, rather than reflecting it back to space. This amplifies the warming effect of increasing greenhouse gases by 25 to 40 percent.”

- On the other side of the planet, the opposite seasonal cycle just concluded with the end of summer. Sea ice around Antarctica reached its annual minimum extent on February 20-21, 2020.

- “The Antarctic sea ice coverage continues the small rebound that it has experienced since its precipitous decline from 2014 to 2017,” Parkinson said, “although it is nowhere close to rebounding to its record high 2014 expanse.”

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Figure 9: This map shows the extent of sea ice around Antarctica on February 21 as measured by satellites. Sea ice that day measured 2.69 million km2 (1.04 million square miles)—continuing a recovery observed in recent years, but still below the 1981-2010 average (image credit: NASA Earth Observatory)

• February 4, 2020: A polar bear’s life seems simple enough: eat seals, mate, and raise cubs. But a recent study shows some subpopulations of polar bears are struggling to complete these essential tasks because of declining concentrations of Arctic sea ice. 16)

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Figure 10: The team specifically studied a subpopulation of bears that depend on seasonal sea ice in Baffin Bay. The team tracked polar bear movements across the bay over the past two decades. The map shows the movements of 43 tagged adult females from 1991-1997 (left) and 38 adult females from 2009-2015 (right) using data from DMSP missions of the instruments SSM/I and SSMIS and in situ measurements from SMMR of Nimbus-7 [image credit: NASA Earth Observatory, image by Joshua Stevens, using data courtesy of Kristin Laidre and Harry Stern at the University of Washington, and sea ice data from the National Snow & Ice Data Center (NSIDC). Story by Kasha Patel]

- The Arctic sea ice cap is a large area of frozen seawater floating on top of the Arctic Ocean and its surrounding seas and straits. For polar bears, the sea ice is a crucial platform for life. They use the ice to travel long distances to new areas. They hunt for seals by finding their dens or sitting next to gaps in the ice, waiting for the unsuspecting prey to pop up. Sometimes, pregnant females dig in the sea ice to create maternity dens, where they give birth and take care of their cubs.

- In recent decades though, this critical habitat has been shrinking. Sea ice concentrations have declined by 13 percent each decade since 1979 due to increasing global temperatures. Arctic regions have warmed twice as fast as the rest of the world, so seasonal sea ice is also forming later in the fall and breaking up earlier in the spring.

- “We know that sea ice, which is where the bears need to be, is decreasing very rapidly,” said Kristin Laidre, an Arctic ecologist at the University of Washington. “When there’s no sea ice platform, the bears end up moving onto land with no or minimal access to food. Our research looked at how these changes affect their body condition and reproduction.”

- In a new study published in Ecological Applications, Laidre and her colleagues described how declining sea ice concentrations are affecting the behavior, health, and reproductive success of polar bears. Using field observations and remote sensing, the study showed that polar bears are spending more time on land and are fasting for longer periods of time. Mother bears are also producing smaller cub litters, which the team projected will continue to decline for the next three polar bear generations. 17)

- “Climate-induced changes in the Arctic are affecting polar bears,” said Laidre, who was the main author of the study. “They are an icon of climate change, but they’re also an early indicator of climate change because they are so dependent on sea ice.”

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Figure 11: This map shows the difference in sea ice extent around Baffin Bay on July 15, 1993 and July 15, 2013. The satellite data are processed by NASA-funded scientists and stored at the National Snow and Ice Data Center. The graph below shows the onshore arrival and departure of polar bears on Baffin Island relative to dates of sea ice advance and retreat. Sea ice has been breaking up earlier in the spring over the years (green) and is forming later in the fall (blue).

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Figure 12: The graph shows the onshore arrival and departure of polar bears on Baffin Island relative to dates of sea ice advance and retreat. Sea ice has been breaking up earlier in the spring over the years (green) and is forming later in the fall (blue), image credit: NASA Earth Observatory, map by Joshua Stevens, using data courtesy of Kristin Laidre and Harry Stern at the University of Washington, and sea ice data from the National Snow & Ice Data Center (NSIDC). Story by Kasha Patel

- The study team found that most bears follow the seasonal growth and recession of sea ice to end up on Baffin Island in the fall, when sea ice is usually at its lowest extent. They usually wait on Baffin Island until the ice forms again so they can leave. On average, the bears are spending 30 more days on land now than they did in the 1990s. Laidre says that is because the ice is retreating earlier and there has been more open water in recent summers.

- “That’s important because when the bears are on land, they do not hunt seals,” said Laidre. “They have the ability to fast, but if they don’t eat for longer periods, they get thinner. This can affect their overall health and reproductive success.”

- To assess polar bear health, the team quantified the condition of bears by assessing their level of fatness after sedating them or inspecting them visually from the air. Laidre and colleagues classified fatness on a scale of 1 to 5. Results showed the bears’ body condition was linked with sea ice availability in the current and previous year.

- Cub litter size was also affected by the body condition of the mothers and by sea-ice availability. The researchers found larger litter sizes when the mothers were in a good body condition and when spring breakup occurred later in the year, meaning bears had more time on the sea ice in spring to find food.

- Then finally, the team used mathematical models to forecast future reproductive success. The model took into account the relationship between sea-ice availability and the bears’ body fat and variable litter sizes. They projected that the normal cub litter size of two may decrease within the next three polar bear generations (37 years), mainly due to the projected decline of sea ice in the coming decades.

- The results of the study were not necessarily surprising for Laidre, who has been studying the changes in the Arctic ecosystem for the past 20 years. She says it is well known that changes in the climate are having a negative effect on polar bears. Even if greenhouse gases were curbed immediately, sea ice would likely continue to decline for several decades because large-scale changes take a long time to propagate through Earth’s climate system.

- In the meantime, Laidre hopes this study’s information will be used to further understand the impacts of sea ice loss on the species. “Polar bears are a harbinger for the future,” said Laidre. “The changes we document here are going to affect everyone around the globe.”

• September 24, 2019: The long-term trend for Arctic sea ice extent has been definitively downward. Arctic sea ice reached its annual summer minimum on September 18, 2019, according to NASA and the National Snow and Ice Data Center (NSIDC). Analysis of satellite data by NSIDC and NASA showed that the extent of ice cover this year effectively tied 2007 and 2016 as the second lowest in the satellite record, which dates back to late 1978. The sea ice cap shrank to 4.15 million km2 (1.60 million square miles) in 2019. 18)

- The Arctic sea ice cap is an expanse of frozen seawater floating on top of the Arctic Ocean and neighboring seas. Every year it expands and thickens during the fall and winter, then grows smaller and thinner during the spring and summer. But in recent decades, increasing air and water temperatures have caused marked decreases in Arctic sea ice extents in all seasons, with particularly rapid reductions in the summer ice extent.

- Changes in Arctic sea ice cover have wide-ranging impacts. The sea ice affects local ecosystems, regional and global weather patterns, and the circulation of the oceans.

- “This year’s minimum shows that there is no sign that the sea ice cover is rebounding,” said Claire Parkinson, a senior scientist at NASA’s Goddard Space Flight Center. “The long-term trend for the Arctic sea ice extent has been definitively downward.”

- “This was an interesting melt season,” said Walt Meier, a sea ice researcher at NSIDC. The season started with a very low sea ice extent in May, followed by very rapid ice loss in July and the beginning of August. “At the beginning of August, we were at record low ice levels for that time of the year, so a new minimum record low could have been in the offering.”

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Figure 13: This map shows the extent of Arctic sea ice as measured by satellites on September 18, 2019. Extent is defined as the total area in which the ice concentration is at least 15 percent. The yellow outline shows the median September sea ice extent from 1981–2010; according to NSIDC data, the median minimum extent for 1979–2010 was 6.33 million km2 (2.44 million square miles). Microwave instruments onboard U.S. Department of Defense meteorological satellites monitored the changes from space (image credit: NASA Earth Observatory image by Joshua Stevens, using data from the National Snow and Ice Data Center. Story by Maria-José Viñas, NASA’s Earth Science News Team)

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Figure 14: This photo, taken during an Operation IceBridge flight on September 9, 2019, shows an opening in the sea ice cover north of Greenland. The lead is partially filled by much smaller sea ice rubble and floes (image credit: NASA Earth Observatory, photograph by Linette Boisvert. Story by Maria-José Viñas, NASA’s Earth Science News Team)

- Unlike 2012—when a powerful August cyclone smashed the ice cover and accelerated its decline to the lowest ice extent on record — this melt season did not bring any extreme weather events. Although areas within the Arctic Circle saw average temperatures 4 to 5º Celsius above normal, events such as the severe Arctic wildfire season and the European heat wave did not have much impact on sea ice melting.

- “By the time the Siberian fires kicked into high gear in late July, the Sun was already getting low in the Arctic, so the effect of the soot darkening the sea ice surface wasn’t that large,” Meier said. “As for the European heat wave, it definitely affected land ice loss in Greenland and also caused a spike in melt along Greenland’s east coast. But that is an area where sea ice is being transported down the coast and melting fairly quickly anyway.”

• March 9, 2018: Arctic sea ice reaches its maximum extent each March, following months of growth during usually frigid and dark autumn and winter. The date of maximum extent for winter 2018 has yet to be determined, but in February 2018, the average ice extent was the lowest of any February on record. 19)

- The map of Figure 16 shows the average concentration of Arctic sea ice in February 2018. Opaque white areas indicate the greatest concentration, and dark blue areas are open water. All icy areas pictured here had an ice concentration of at least 15 percent (the minimum at which space-based measurements give a reliable measurement), and cover a total area that scientists refer to as the “ice extent.”

- The February extent averaged 13.95 million km2, according to the NSIDC (National Snow & Ice Data Center). That is 1.35 million km2 below the 1981–2010 average for February. The chart of Figure 15 shows how Arctic sea ice growth this year compares with all years since 1979.

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Figure 15: Chart of average Arctic sea ice growth in 2018 compared with all years since 1979 using data from DMSP instruments SSM/I and SSMIS as well as data from SMMR of Nimbus-7 (image credit: NASA Earth Observatory, NSIDC)

- The lackluster ice growth—and the decline in areas such as the Bering and Chukchi seas—was influenced by a so-called “winter warming event.” (Read about the complex chain of events that lead to these events here.) Low pressure off of Greenland and high pressure over Europe helped move warm air masses—and possibly some warm water—from the North Atlantic into the Arctic Ocean. A similar scenario also played out on the Pacific side: low- and high-pressure systems set up in such a way as to move warm air and water from the North Pacific through the Bering Strait.

- “We have seen winter warming events before, but they’re becoming more frequent and more intense,” said Alek Petty, a sea ice researcher at NASA’s Goddard Space Flight Center.

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Figure 16: Map of the average concentration of Arctic sea ice, acquired in February 2018 (image credit: NASA Earth Observatory, images by Joshua Stevens, using data from the NSIDC and NCEP reanalysis data provided by the NOAA/OAR/ESRL PSD. Story by Kathryn Hansen with reporting by Maria-José Viñas/NASA’s Earth Science News Team)

- Areas of unusual warmth are visible in the map of Figure 17, which shows air temperature anomalies for February 2018. Red and orange colors depict areas that were hotter than average; blues were colder than average. At times, the North Pole saw temperatures climb above freezing, soaring 20 to 30 ºC above the norm.

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Figure 17: Temperature anomalies in the Arctic ocean in February 2018 (image credit: NASA Earth Observatory, NSIDC)

- Notice the area north of Greenland. This is the site of another exceptional event this winter: open water instead of sea ice cover. Without the ice cover here, heat is being released from the ocean to the atmosphere, making the sea ice more vulnerable to further melting. “This is a region where we have the thickest multi-year sea ice and expect it to not be mobile, to be resilient,” Petty said. “But now this ice is moving pretty quickly, pushed by strong southerly winds and probably affected by the warm temperatures, too.”

- NASA’s Operation IceBridge—an airborne mission to map polar ice—will make measurements in the area when annual science flights resume in late March 2018.

• December 20, 2017: With the help of Secretary of the Air Force Heather Wilson, the SMC (Space and Missile Systems Center) has unveiled the final Defense Meteorological Support Program satellite, DMSP-20, for display at the Schriever Space Complex within the Gordon Conference Center. 20) 21)

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Figure 18: Secretary of the Air Force Heather Wilson and Air Force Lt. Gen. John Thompson, commander of the Space and Missile Systems Center and Program Executive Officer for Space, pose for a photo with Air Force 2nd Lt Zachary Nuss, far left, and Dr. Steven Pluntze, far right, in front of a decommissioned Defense Meteorological Satellite Program 20 satellite during the Space and Missile Systems Center's lecture series, Airmen Everywhere, at Los Angeles Air Force Base in El Segundo, Calif., Dec. 14, 2017. DMSP-20, was dismantled and put in a museum instead of launched (image credit: U.S. Air Force photo/Sarah Corrice)

- "This display represents a nearly 60-year history of environmental monitoring success by a satellite constellation that continues to provide crucial weather information to our nation's leaders, civil users, and warfighters," said Wilson. DMSP got its start in 1961, when the National Reconnaissance Office established a meteorological satellite program to provide information on cloud cover over the Soviet Union for the once highly-classified Corona photographic reconnaissance satellites.

- Retired Air Force Col. Thomas Haig, recently presented with a piece of the DMSP-20 satellite on Aug. 9, was selected to create and manage DMSP.

- Although intended as an interim program, the highly successful DMSP was transferred to the Space Systems Division - forerunner of today's SMC - and launched its first satellite into low earth orbit on Aug. 23, 1962.

- In the intervening six decades, DMSP has had an impressive succession of successes. It provided the earliest tactical uses of spaceborne weather information and the world's first use of satellite imagery to support tactical military operations during the Vietnam conflict. The information DMSP provides has been crucial to the support of military operations ever since, from first Gulf War to real-time situational awareness for current operations in Iraq and Afghanistan.

- "But DMSP supports more than just military operations," explained Lt. Gen. John Thompson, SMC commander and Air Force program executive officer for space. ”NOAA and various other civil and humanitarian organizations use DMSP imagery and data for weather forecasting. This includes numerous missions that rely on data from snow cover and tropical cyclone intensity to cloud temperatures and magnetic fields in space. Even NASA uses DMSP weather information to help plan future launches, as they did with launches stretching back to the Apollo and Space Shuttle programs."

- Although the final DMSP satellite launched in 2014 (DMSP-19), the constellation as a whole will continue to provide data used to create weather forecast models and provide crucial weather information for the foreseeable future.

- This includes DMSP-14, which was launched in 1997 and completed its historic 100,000th orbit around the Earth last summer.

- "The fact that DMSP-14 is providing weather data 17 years past its designed mission life of three years is a testament to the craftsmanship of the satellite and the hard work of the government and contractor teams who continue to make the DMSP program a resounding success," said Dr. Stephen Pluntze, deputy director of SMC's Remote Sensing Systems Directorate and former director of the Defense Weather Systems Directorate.

- The SMC (Space and Missile Systems Center) was responsible for procuring DMSP satellites. The DMSP constellation is operated by a coalition of mission partners including NOAA's Office of Satellite and Product Operations and the 50th Operations Group Detachment 1, both located in Suitland, Maryland.

- Backup command and control operations are conducted by the 6th Space Operations Squadron located at Schriever AFB, Colorado. Lockheed Martin Space Systems designed the spacecraft, and Northrop Grumman worked with the Air Force Research Laboratory to provide the sensors integrated onto the spacecraft.

- SMC, located at Los Angeles Air Force Base in El Segundo, California, is the U.S. Air Force Space Command's center of excellence for acquiring and developing military space systems. SMC's portfolio includes the Global Positioning System, military satellite communications, defense meteorological satellites, space launch enterprise, satellite control networks, remote sensing systems, and space situational awareness capabilities.

• November 8, 2017: For 18 years, a fully-built, ready-to-launch weather satellite sat inside a Lockheed Martin facility near Moffett Field in Sunnyvale, California. Scientists were waiting for the spacecraft to be called into active duty since it was completed during the Clinton administration. 22)

- A different order from Washington arrived instead. Because of resistance in Congress — particularly from Rep. Michael Rogers of Alabama, who chairs a key House Defense subcommittee — Capitol Hill told the Air Force to take the satellite apart.

- Congress simply refused to fund the Air Force's request for $120 million to launch the spacecraft, even though the service said it was needed for weather forecasting, a crucial aspect of battlefield planning. In addition, climate scientists were counting on that satellite to help them monitor Arctic ice melt.

- Now, instead of helping scientists and members of the military, the satellite will go on display — stripped of its expensive instruments — next month in a museum at Los Angeles Air Force Base in El Segundo, California.

- The decision to dismantle the satellite shocked scientists, who were hoping to use a microwave sensor aboard it to help them avoid a dangerous gap in Arctic sea ice data that may open up between now and 2023. That is the estimated year when the next Air Force weather satellite launch is planned.

• August 4, 2017: The DMSP -19 mission will soon cease transmitting weather data after nearly three and a half years of operational service, the U.S. Air Force said. 23)

- There is no impact to the strategic weather mission, and the DMSP constellation remains able to support military requirements through resilient systems and processes, the Air Force reported. The remainder of the constellation continues to provide weather and atmospheric data to users.

- Operators lost the ability to command the satellite Feb. 11, 2016, following a power failure within the command and control system, the Air Force noted. Since that time the satellite has provided tactical data to field units but has not provided full-orbit weather imagery to the 557th Weather Wing, Offutt Air Force Base, Neb., and the U.S. Navy’s Fleet Numerical Meteorology and Oceanography Center, Monterey, CA.

- The DMSP operations team has remained in regular contact with the vehicle and continued to monitor telemetry since the incident, the Air Force said. However, the team acknowledged a loss of attitude control was unavoidable due to the inability to command. Once the satellite loses attitude control it will begin to tumble, causing the power system to deplete and all satellite transmissions to cease. The tumble is predicted to occur late next month. The Joint Space Operations Center will track the satellite and provide conjunction warnings if required.

- DMSP F-19 was launched in April 2014. While space-based weather assets were originally launched and operated by the U.S. Air Force, a 1994 presidential directive realigned primary command and control of DMSP under the Department of Commerce’s National Oceanic and Atmospheric Administration.

• December 16, 2016: As previously reported, the Arctic sea ice cover was lower in November 2016 than any other November in the satellite record. It turns out that the Arctic was not alone. Sea ice at the other pole, around Antarctica, also reached a record November low. 24)

- During this time of year, the Arctic Ocean and neighboring seas are refreezing after the annual summer melt season. Conversely, the sea ice fringing Antarctica is normally melting at this time of year, during the austral spring and summer. What is unusual is the amount of melting so far in the Antarctic, spurred by warm air temperatures and shifting winds.

- The ice extent for November 2016 averaged just 14.54 million km2. The yellow line of Figure 19 shows the median extent from 1981 to 2010, and gives an idea of how conditions this November strayed from the norm. Specifically, the November extent this year was 1.81 million km2 below the 1981 to 2010 average.

- The melt season started early this year, after Antarctic sea ice reached its annual maximum extent on August 31. By November, the ice reached daily record lows amid air temperatures that were 2 to 4 degrees Celsius above average. Winds that usually disperse the ice instead shifted direction and compressed it around various land areas.

- It remains to be seen how much Antarctic sea ice will melt during the remainder of the season; sea ice usually reaches its annual minimum extent in February. In some places around the continent, sea ice can melt completely before starting the annual cycle of refreezing.

- In recent years, notably from 2012 to 2014, the period of refreezing has culminated in record-high maximum extents. On an annual basis, the total Antarctic sea ice extent has increased about 1 percent per decade since 1979. Still, the long-term trend still shows a global decline in sea ice. The chart of global extent demonstrates how, over the long term, the slight increases in Antarctic sea ice have not offset the large losses in the Arctic.

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Figure 19: The map shows the average concentration of Antarctic sea ice for November 2016, acquired by SSM/I of DMSP. Opaque white areas indicate the greatest concentration, and dark blue areas are open water. All icy areas pictured here have an ice concentration of at least 15 percent (the minimum at which spaceborne measurements give a reliable measure), and cover a total area that scientists refer to as the “ice extent” (image credit: NASA Earth Observatory images by Joshua Stevens, using data from the National Snow and Ice Data Center. Caption by Kathryn Hansen)

• July 25, 2016: The satellite anomaly resolution team recently closed their investigation into the DMSP-19 anomaly. The anomaly team determined there was a power failure within the command and control system that affected onboard cryptographic equipment. Due to this failure, commands are unable to reach the command processor. Both the A and B side of the command and control subsystem failed, eliminating the possibility of commanding via a back-up command path. The satellite is not repairable and no further action will be taken to recover it. A power failure, as well as an interface failure, resulted in the loss of both command paths to the control unit. 25)

- The team was able to verify the error using approved methods for troubleshooting and identifying root causes of satellite anomalies. The satellite remains in a safe and stable configuration and there have been no ejection or breakup-type events. The operations team is still in contact with the vehicle and will continue to monitor and gather telemetry as long as the vehicle remains pointed toward the Earth.

- The satellite continues to provide real-time tactical data to users; however, data received will begin to deteriorate as the satellite's pointing accuracy degrades. When tactical data are no longer available, the satellite will be tracked as one of many space objects for situational awareness and collision avoidance purposes.

- At this time, there is no impact to the DoD (Department of Defense) core weather sensing mission and the DMSP constellation remains able to support mission requirements through resilient systems and processes. DMSP -17 is now assigned as one of two primary constellation satellites to reduce any potential impact to users. The other primary satellite is DMSP-18. As has been the case for the past five decades, the constellation continues to provide weather and atmospheric data to users.

• March 7, 2016: The DMSP-F19 spacecraft stopped responding to orders from the ground on Feb. 11, the Air Force said in a March 3 press release. Satellite operators in Suitland, Maryland, are still receiving telemetry from DMSP-F19 after the Feb. 11 anomaly, but it is unclear whether engineers can recover the satellite and continue its mission. DMSP-19, the newest spacecraft in the USAF weather satellite series, was launched on April 19, 2014. 26)

- The Air Force said the DMSP-F17 satellite, launched in November 2006, has been reassigned as the primary DMSP spacecraft, taking over for the crippled DMSP-F19.

• July 24, 2015: Investigators have traced the cause of an in-space disintegration of a U.S. Air Force weather satellite DMSP-F13 in February to a battery fault and identified six other spacecraft in orbit prone to the same failure. Engineers originally suspected the polar-orbiting satellite’s power system was to blame for the Feb. 3, 2015 explosion, which littered the low Earth orbit with 147 objects ranging from the size of a baseball to the size of a basketball, according to an Air Force press release. 27)

- A report from engineers investigating the break-up of the DMSP-F13 (Defense Meteorological Satellite Program -Flight 13) spacecraft revealed the probable cause of the failure was a compromised wiring harness inside a battery charger aboard the satellite. The report also detailed how satellite controllers on the ground responded to the mishap and decommissioned the weather observatory within hours, preventing the potential release of more debris.

- Although the objects large enough to be tracked by U.S. military radars number in the hundreds, researchers from the University of Southampton studying the accident say the rupture generated more than 50,000 fragments larger than 1 mm, many of which will remain in orbit for many decades.

- A design flaw in the satellite’s battery charger led to the accident, and six other DMSP satellites still in orbit could suffer a similar fate, Air Force officials said.

- DMSP-F13 launched aboard an Atlas booster from Vandenberg Air Force Base in California in March 1995. Built by Lockheed Martin, the craft was operating well beyond its four-year design life when it broke apart in February after more than 100,000 orbits around Earth. The satellite was the second-to-last member of the DMSP-5D2 series, which was replaced by an upgraded design to fulfill the Air Force’s weather forecast requirements through the 2000s and 2010s.

- NOAA is charged with uplinking commands to the Air Force’s weather satellites through an inter-agency agreement. While officials identified process improvements to help ground operators respond to future battery emergencies, there is no way to eliminate the risk on the six spacecraft carrying the same battery type as DMSP-F13.

- Only one of the aging DMSP satellites with the faulty battery remains operational — DMSP-F14 launched in 1997 — but retired spacecraft are also prone to battery ruptures.

- Satellite decommissioning procedures typically include the release of high-pressure gases and unconsumed propellant, along with a full discharge of spacecraft batteries, to reduce the chance of an explosion after retirement.

• May 7, 2015: Debris from the DMSP-13 spacecraft, which exploded in Feb. 2015, could pose a threat to other spacecraft and missions according to new research from the University of Southampton. It is estimated, that the explosion produced over 100 pieces of space debris that were detected using radar. In assessing how debris created by the explosion might affect their spacecraft, the European Space Agency and other satellite operators concluded that it would pose little risk to their missions. 28) 29)

- However, scientists from the Astronautics Research Group at the University of Southampton (UK) investigated the risks to a wide range of space missions, coming from smaller pieces of debris created by the explosion that cannot be detected using radar based on the ground. In the case of the explosion of DMSP-F13, they detected 100 new catalogued objects, which suggest that more than 50,000 small fragments larger than 1mm were created.

- The Southampton team developed a new technique called CiELO (debris Cloud Evolution in Low Orbits) to assess the collision risk to space missions from small-sized debris. They produced a collision probability map showing a peak in the risk at altitudes just below the location of the DMSP-F13 explosion. The map was created by treating the debris cloud produced by the explosion as a fluid, whose density changes under the effect of atmospheric drag.

• March 2015: The DMSP-F13 spacecraft, launched on March 24, 1995, apparently exploded in orbit Feb. 3, 2015, following what the U.S. Air Force described as a sudden temperature spike. The “catastrophic event” produced 43 pieces of space debris, according to Air Force Space Command, which disclosed the loss of the satellite on Feb. 27, 2015. The satellite, Defense Meteorological Satellite Program Flight 13, was the oldest continuously operational satellite in the DMSP weather constellation. However, it was not the first DMSP satellite to explode after years of reliable service. 30)

- According to the Air Force Space Command, the DMSP-F13’s power subsystem experienced a sudden spike in temperature, followed by an unrecoverable loss of attitude control. The JSpOC (Joint Space Operations Center) of the US Air Force, located at VAFB, CA, identified a debris field near the satellite. The USAF is continuing to track the debris and will issue conjunction warnings if necessary.

- The Air Force still has six DMSP satellites in service following the launch in April 2014 of DMSP-F19.

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Figure 20: Continuity of NOAA's Polar (Primary) Operational Weather Satellite Programs(as of May 2014) 31)

• On August 19, 2014, the DMSP F-19 spacecraft, launched April 3, 2014, was accepted for operations by U.S. Strategic Command (USSTRATCOM). This acceptance formally adds DMSP Flight-19 to the existing DMSP constellation. As DMSP-19 enters its service life, a joint team of the Air Force and NOAA (National Oceanic and Atmospheric Administration) is controlling the satellite from Suitland, Maryland. DMSP-19 joined six other sister satellites in polar orbit. 32)

• The DMSP F-16, F-17 and F-18 spacecraft are operational in 2011. The F-18 spacecraft became operational in March 2010. 33) 34)

• In 2009, the DMSP satellite series continues to provide timely worldwide meteorological and ionospheric data to military users and the civilian community. The current constellation consists of two primary operational (F-16, and F-17) and three partially operational satellites (F-13, F-15). 35)

Satellite

F-13

F-14

F-15

F-16

F-17

Ascending node

18:32 hours

17:22 hours

19:35 hours

20:03 hours

17:32 hours

Status

secondary

secondary

secondary

primary

primary

Table 3: Overview of operational DMSP spacecraft

• The SSMI instrument on the F-14 mission lost onboard storage in August 2008; F-13 shows worsening seasonal receiver gain fluctuations and tape recorder problems. 36)

- The SSMIS sensor series (F-16 since 2003, F-17 since 2006, F-18 since Oct. 2009, (and F-19 to -20 yet to be launched) will be a key constellation member in the GPM (Global Precipitation Mission) era. 37)

- The SSMIS instruments of the F-16 and F-17 missions are affected by two significant instrument problems: solar intrusions into the warm load, and thermal emission from the reflector.

• As of Jan. 29, 2007, the F-17 spacecraft had completed its on-orbit checkout phase and was declared “operational” (launch of DMSP F-17 on Nov. 4, 2006). The checkout team included representatives of the Air Force, NOAA, Northrop Grumman, and the Aerospace Corporation. This implies that NOAA can begin a regular operational service with DMSP F-17. 38) 39)

• As of Nov. 20, 2003, the F-16 spacecraft had completed its on-orbit checkout phase and was declared “operational” (launch of DMSP F-16 on Oct. 16, 2003). 40)