| The satellites of the Defense Meteorological Satellite Program (DMSP) are a series of low-altitude (~850 km), polar-orbiting spacecraft. Their primary mission is to observe the tropospheric weather. The primary sensor system used to accomplish this mission is the Operational Linescan System (OLS), a high resolution (2.8 km), white-light and infra-red imaging system. The secondary mission of DMSP is to monitor the space environment, which is important to the Air Force because of the various ground-based and space-based systems that can be affected by the space environment. |
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Nominal Orbit: 458 n.mi. (848 km), 98.8 Deg inclination, 0.001 eccentricity, Sun-synchronous
Local Time of Ascending/Descending Node (Equator Crossing) of Recent Spacecraft:
| Satellite | Nominal L.T. of Node | Actual L.T. of Node (Click on the times to see plots of the change in the orbit over the spacecraft lifetime) |
|---|---|---|
| F8 |
0600 / 1800 |
0610 / 1810 |
| F9 |
0930 / 2130 |
0932 / 2132 |
| F10 |
2030 / 0830 |
1944 / 0744 (1991) 2218 / 1018 (1997) |
| F11 |
1730 / 0530 |
1659 / 0459 (1992) 1919 / 0719 (1998) |
| F12 |
2030 / 0830 |
2049 / 0849 |
| F13 |
1730 / 0530 |
1711 / 0511 |
| F14 |
2030 / 0830 |
2035 / 0835 |
| F15 |
2110 / 0910 |
2110 / 0910 (2000), ~1800/0600 (2009) |
| F16 |
1954/0754 |
2000/0800 |
| F17 |
1734/0534 |
1736/0536 |
| F18 |
2000/0800 |
2000/0800 |
For a geographic latitude of 45° N, the local time of the spacecraft is approximately 34 minutes earlier (later) on the morning (evening) side of the orbit for F8 and F9. For F10 and beyond, the change in local time is reversed. For geographic latitude of 45° N, the local time of the spacecraft is approximately 34 minute earlier (later) on the evening (morning) side of the orbit.
If you click on the actual local times in the table above, a graph will appear to show the variation in local time for 45° N, the geog. Equator, and 45° S for the morning and evening sides of the orbits. The lines vary a few minute during each year due to a slight non-uniformity in the Earth path around the Sun (which is sometimes referred to as the Equation of Time.
Space Environment Instrumentation of Recent and Planned Spacecraft:
Note 1: Due to problem with reflected sunlight, there are some data drops of a few minutes each orbit in the SSJ4 instrument on F12. To compensate for the F12 SSJ4 data drops, the F10 SSJ4 data continued to be acquired.
Note 2: After the launch and checkout of the F14 spacecraft, the F12 data stream was not turned off, as was normally done prior to 1997. Instead, after 28 April 1997 about half the orbits of data were received, processed and archived. After 01/24/2000, only one recorder was in use; this severely limited coverage. After Nov 2001, the quality of the data is very poor due to the tape recorder. On 07/27/2002, the tape recorder completely stopped working and no usable data is available.
Note 3: After the spacecraft ceased to be operational, a limited number of orbits of data were acquired each day. Some days the number of orbits acquired was nearly 100% and some days it was nearly 0%.
Note 4: The SSIES and SSJ4 instruments on F11 were turned off on 06 Jun 1999 due to lack of spacecraft power. These instruments were turned back on 13 Jan 2000 and then turned off on 16 May 2000.
Note 5: WARNING The SSJ4 instruments on F13 and F15 have degraded low energy ion detectors (30 eV to 1 keV). For F13, the degradation slowly became noticeable in 1995 after many months of usage. From early 1996 to current, users should not rely on any outputs from the low energy ion detector. For F15, the degradation occurred rapidly. After one month in orbit, the F15 low energy ion detector data should not be used. For 1999 and onwards, the data from all instruments on F11 and F12 are noisy due to aging spacecraft systems.
Note 6: On 20 Dec 2002 at approximately 0920 U.T., the data formatter inside the OLS crashed. The SSIES, SSJ4 and SSM were automatically turned off. The backup data formatter was activated and the space weather instrument were turned back on approximately 1600 U.T. on 23 Dec 2003.
Note 7: As of Read-out Rev 43810 (29 Sept 2005 approx 13 hrs UT), data the F14 SSJ4 sensor is no longer processed and archived. The quality of the precipitating electron data had degraded from 2001 to 2005 to such a degree that the electron data was no longer considered useful. Data from the F14 SSIES and SSM sensors continues to be processed and archived.
Note 8: On 2 November 2006, the F14 SSM experienced an unknown problem which resulted in unusable data being produced from that date to 8 March 2007. A similar outage of SSM data started on 13 Feb 2008 and continue until at least 26 March 2008.
Note 9: on Tuesday 14 March 2009SSJ4 on F15 Rev 47965 at 17:15 Z, the SSJ4 was turned off due to degradation of the detector element
Note 10: On 18 November 2009, the last functioning tape recorder on F13 failed. The instruments are still working but there will not be any more data added to the archive.
Note 11: The F19 spacecraft stopped responding to commands from mission control and engineers have concluded that a power anomaly inside the satellite is responsible for the weather observatory’s failure.
These Instrument Acronyms stand for: (organization responsible for instrument is in parentheses)
Some of the space environment data can be obtained from NOAA/ National Centers for Environmental Information, Boulder, CO. Other data may be available from University of Texas at Dallas web site, from BC by request) or the organization responsible for an instrument listed above.
Updated 19 March 2014
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