View source for Defense Support Program

{{Short description|US infrared satellite early warning system}}
{{More citations needed|date=December 2019}}
{{Use American English|date=January 2014}}
{{Use dmy dates|date=April 2017}}

[[File:DSP Phase3.jpg|thumb|right|260px|Painting of a DSP satellite on station. Primary sensor (lower left) is pointed at Earth. The star tracker is seen pointing off to the side, above and to the right.]]

The '''Defense Support Program''' ('''DSP''') is a program of the [[United States Space Force]] that operated the [[reconnaissance satellite]]s which form the principal component of the ''Satellite Early Warning System'' used by the United States.

DSP satellites, which are operated by the [[460th Space Wing]], detect [[missile]] or [[spacecraft]] launches and [[nuclear weapon|nuclear]] explosions using sensors that detect the [[infrared]] emissions from these intense sources of heat. During [[Desert Storm]], for example, DSP was able to detect the launches of Iraqi [[Scud]] missiles and provide timely warnings to civilians and military forces in Israel and [[Saudi Arabia]].<ref>{{cite web|url=http://www.fas.org/spp/military/program/warning/dsp.htm|title=Defense Support program|publisher=Fas.org|access-date=26 October 2013|archive-url=https://web.archive.org/web/20140808022715/http://fas.org/spp/military/program/warning/dsp.htm|archive-date=8 August 2014|url-status=live}} {{PD-notice}}</ref>

The satellites are in [[geosynchronous orbit]]s, and are equipped with infrared sensors operating through a wide-angle [[Schmidt camera]]. The entire satellite spins so that the linear [[sensor array]] in the focal plane scans over the Earth six times every minute.<ref>{{cite web|url=http://www.afspc.af.mil/library/factsheets/factsheet.asp?id=9206|title=Factsheets : DSP Animation Only|publisher=afspc.af.mil|date=19 July 2007|access-date=26 October 2013|url-status=dead|archive-url=https://web.archive.org/web/20131029195801/http://www.afspc.af.mil/library/factsheets/factsheet.asp?id=9206|archive-date=29 October 2013}} {{PD-notice}}</ref>

Typically, DSP satellites were launched on [[Titan IV]]B boosters with [[Inertial Upper Stage]]s. However, one DSP satellite (DSP-16) was launched using the [[Space Shuttle Atlantis]] on mission [[STS-44]] (24 November 1991).

The last known DSP satellite (flight 23) was launched in 2007 aboard the first operational flight of the [[Delta IV rocket|Delta IV Heavy]] rocket, as the Titan IV had been retired in 2005. All 23 satellites were built by the prime contractor [[Northrop Grumman|Northrop Grumman Aerospace Systems]], formerly [[TRW Inc.|TRW]], in [[Redondo Beach, California|Redondo Beach]], [[California]].<ref>https://fas.org/sgp/crs/weapons/RS21148.pdf {{PD-notice}}</ref>

The [[460th Space Wing]], with headquarters at [[Buckley Space Force Base]], [[Colorado]], has units, primarily the [[2nd Space Warning Squadron]], that operate DSP satellites and report warning information, via communications links, to the [[North American Aerospace Defense Command|NORAD]] and [[United States Strategic Command|USSTRATCOM]] early warning centers within the [[Cheyenne Mountain Space Force Station]], Colorado. These centers immediately forward data to various agencies and areas of operations around the world.{{citation needed|date=December 2019}}

The SBIRS Wing at the [[Space Systems Command]], [[Los Angeles Space Force Base]], California is responsible for development and acquisition of the satellites.<ref>{{cite web |url=https://www.losangeles.spaceforce.mil/?id=5514|title=Factsheets : Infrared Space Systems Directorate|publisher=Losangeles.af.mil|date=21 November 2012|access-date=26 October 2013 |url-status=live|archive-url=https://web.archive.org/web/20130824010931/http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=5514|archive-date=24 August 2013}} {{PD-notice}}</ref>

== History ==
The Defense Support Program replaced the 1960s space-based infrared [[Missile Defense Alarm System]] (MIDAS). The first successful launch of [[Missile Defense Alarm System|MIDAS]] (MIDAS-2) was 24 May 1960 and there were twelve launches before the DSP program replaced it in 1970.

Benefiting from funds released by the cancellation of [[Manned Orbiting Laboratory]],<ref name="tsr20240102">{{Cite web |last1=Hendrickx |first1=Bart |last2=Day |first2=Dwayne A. |author-link2=Dwayne A. Day |date=2024-01-02 |title=The Space Review: Diamonds and DORIANS: The Soviet Union's Almaz and the United States' Manned Orbiting Laboratory military space stations (part 3) |url=https://www.thespacereview.com/article/4717/1 |access-date=2024-01-03 |website=The Space Review}}</ref> the first launch of a DSP (IMEWS-1 - [[Integrated Missile Early Warning Satellite]])<ref name="Display">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-093A|title=Display: IMEWS-1 1970-093A|publisher=NASA|date=14 May 2020|access-date=13 August 2020}}</ref> was on 6 November 1970 and since then it has become the mainstay of the United States ballistic missile early warning system. For the last 45 years they have provided an uninterrupted space-based early warning capability. The original DSP satellite weighed 2,000 pounds (900&nbsp;kg) and had 400 watts of power, 2000 detectors and a design life of 1.25 years.

Throughout the life of the program, the satellite design has undergone numerous improvements to enhance reliability and capability. The weight grew to 5,250 pounds (2380&nbsp;kg), the power to 1275 watts, the number of detectors increased threefold to 6000 and the design life has been increased to a goal of ten years.

[[File:STS-44 DSP deployment.jpg|thumb|220px|DSP satellite deployment during [[STS-44]]]]

The numerous improvement projects have enabled DSP to provide accurate, reliable data in the face of evolving missile threats. On-station sensor reliability has provided uninterrupted service well past their design lifetime. Recent technological improvements in sensor design include above-the-horizon capability and improved resolution. Increased on-board signal-processing capability improves clutter rejection. Enhanced reliability and survivability improvements were also incorporated.

The 23rd, and last DSP satellite (DSP-23) was scheduled to be launched on 1 April 2007, aboard a [[Delta IV rocket|Delta IV Heavy rocket]], but the launch was postponed until mid-August 2007 after two structural cracks were found in the metal launch table at pad 37B, caused by a fuel leak during testing. Further delays forced the launch back to 11 November 2007, when the satellite launched at 01:50:00 [[UTC]] (20:50 EST on 10 November). This satellite died in space sometime during 2008, for reasons unknown. It is now adrift in geosynchronous orbit and remains a potential hazard to other craft.

The Department of Defense sent a [[MiTEx]] spacecraft to inspect DSP 23 sometime in 2008.<ref>{{cite web|url=http://www.spaceflightnow.com/news/n0901/14dsp23/|title=Secret inspection satellites boost space intelligence ops|publisher=Spaceflight Now|access-date=26 October 2013|archive-url=https://web.archive.org/web/20131029190550/http://www.spaceflightnow.com/news/n0901/14dsp23/|archive-date=29 October 2013|url-status=live}}</ref>

Another DSP satellite was lost in 1999, DSP-19, after its [[Inertial Upper Stage]] failed following launch from a [[Titan IV|Titan 4B]] booster.<ref>{{cite web |url=http://www.fas.org/spp/military/program/launch/t4table.htm|title=Titan-4 Launch History and Future Schedule|publisher=fas.org|access-date=26 October 2013|archive-url=https://web.archive.org/web/20121031203558/http://www.fas.org/spp/military/program/launch/t4table.htm|archive-date=31 October 2012|url-status=live}} {{PD-notice}}</ref> DSP-19 was a USAF Defense Support Program missile early warning satellite equipped with an [[infrared telescope]] to detect rocket launches. The Titan 4B rocket placed the IUS upper stages and payload into a 188&nbsp;km x 718&nbsp;km x 28.6° parking orbit. The first stage on the IUS burned at 18:14 GMT and put the second stage and payload into a geosynchronous transfer orbit. The IUS second stage fired at 23:34 GMT. However, the two stages of the IUS failed to separate completely. At least one connector remained attached. This meant the second stage motor nozzle did not extend properly. When the stage fired, the vehicle tumbled during the burn and the satellite was left out of control in a useless orbit.

The project was originally to have had 25 satellites, but the last two have been canceled, mainly due to SBIRS. DSP satellites have been replaced by the '''[[Space-Based Infrared System]] (SBIRS)''' satellites.

There were five major improvement programs on the 23 satellites:

* Block 1: Phase I, 1970–1975, five satellites
* Block 2: Phase II, 1976–1987, seven satellites
* Block 3: Multi-Orbit Satellite Performance Improvement Modification (MOS/PIM), 1989–1991, three satellites
* Block 4: Phase II Upgrade, 1994–1997, two satellites
* Block 5: DSP-I (DSP-Improved), 1999–2007, six satellites

More recently, there has been some effort put into using DSPs' infrared sensors as part of an early warning system for natural disasters like volcanic eruptions and forest fires.

== Limitations ==
The DSP constellation may have offered an excellent vantage point for an early warning system against state-centric threats such as missiles, but military analysts warn its ability to collect intelligence on non-state actors is severely limited.<ref>{{Citation|last=Danskine|first=William B., Lt Col, USAF|title=Aggressive ISR in the War on Terrorism – Breaking the Cold War Paradigm|journal=Air & Space Power Journal |issue=Summer 2005|page=76|publisher=USAF|year=2005|url=http://www.airpower.maxwell.af.mil/airchronicles/apj/apj05/sum05/sum05.pdf|access-date=22 May 2007|archive-url=https://web.archive.org/web/20060617215051/http://www.airpower.maxwell.af.mil/airchronicles/apj/apj05/sum05/sum05.pdf|archive-date=17 June 2006|url-status=dead}} {{PD-notice}}</ref>

== General characteristics ==
* Primary mission: strategic and tactical missile launch detection
* Contractor team: [[Northrop Grumman|Northrop Grumman Aerospace Systems]], formerly [[TRW Inc.|TRW]] (for satellite bus) and [[Northrop Grumman Electronic Systems]], formerly [[Aerojet|Aerojet Electronics Systems]] (for [[Infrared|IR]] sensor)
* Weight: 5,250&nbsp;lb (2,380&nbsp;kg)
* Orbit altitude: 22,000 miles (35,900&nbsp;km)
* Power plant: solar arrays generate 1485 watts
* Height: 32.8&nbsp;ft (10 m) on orbit; 28&nbsp;ft (8.5 m) at launch
* Diameter: 22&nbsp;ft (6.7 m) on orbit; 13.7&nbsp;ft (4.2 m) at launch
* Date first deployed: 1970
* Date late deployed: 2007
* Latest Satellite Block: satellites 18–23
* Unit Cost: US$400 million

== Gallery ==
<gallery>
Image:2d Space Warning Squadron.png|[[2d Space Warning Squadron]]
Image:8th Space Warning Squadron.png|[[8th Space Warning Squadron]]
Image:11th Space Warning Squadron.PNG|[[11th Space Warning Squadron]]
Image:DSP Flight 1.png|DSP Flight 1
Image:DSP Flight 2.png|DSP Flight 2
Image:DSP Flight 3.png|DSP Flight 3
Image:DSP Flight 4.png|DSP Flight 4
Image:DSP Flight 5.png|DSP Flight 5
Image:DSP Flight 7.png|DSP Flight 7
Image:DSP Flight 8.png|DSP Flight 8
Image:DSP Flight 9.png|DSP Flight 9
Image:DSP Flight 10.png|DSP Flight 10
Image:DSP Flight 13.png|DSP Flight 13
Image:DSP Flight 14.png|DSP Flight 14
Image:DSP Flight 15.png|DSP Flight 15
Image:DSP Flight 16.png|DSP Flight 16
Image:DSP Flight 17.png|DSP Flight 17
Image:DSP Flight 18.png|DSP Flight 18
Image:DSP Flight 1 Launch 6 Nov 1970.png|DSP F1 Launch 6 November 1970
</gallery>

== See also ==
{{Portal|Spaceflight}}
* [[Missile Defense Alarm System|Missile Defense Alarm System (MIDAS)]]
* [[Space-Based Infrared System|Space Based Infrared System (SBIRS)]]

== References ==
{{Reflist}}

== External links ==
* [http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104611/defense-support-program-satellites.aspx US Air Force DSP Satellites Fact Sheet] {{Webarchive|url=https://web.archive.org/web/20140226130139/http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104611/defense-support-program-satellites.aspx |date=26 February 2014 }}
* [http://www.cyclebikeapp.com Augmented-reality view of DSP satellites] {{Webarchive|url=https://web.archive.org/web/20210225094859/http://www.cyclebikeapp.com/ |date=25 February 2021 }}
* [http://www.heavens-above.com/orbit.aspx?satid=28158 Orbit of DSP F22, the latest operational DSP satellite]

{{USAF Weapons}}
{{US Reconnaissance Satellites}}
{{USAF system codes}}

[[Category:Military satellites]]
[[Category:Missile defense]]
[[Category:Reconnaissance satellites of the United States]]
[[Category:Equipment of the United States Space Force]]
[[Category:Early warning systems]]
[[Category:Military space program of the United States]]
[[Category:Infrared technology]]
[[Category:Early warning satellites]]
[[Category:Spacecraft launched by Delta IV rockets]]
[[Category:Military equipment introduced in the 1970s]]