{{Short description|Part of an American national defense system against ballistic missile attack}} {{Use American English|date=December 2020}} {{use dmy dates|date=December 2020}} {{Infobox spaceflight | name = STSS DEMO-1 / STSS DEMO-2 | names_list = SBIR-Low<br />STSS-1<br />STSS-2<br />USA-208<br />USA-209 | image = Ignition with STSS-Demo.jpg | image_caption = Launch of STSS-Deno | image_size = 290px

| mission_type = Tracking and Surveillance | operator = U.S. Missile Defense Agency | COSPAR_ID = 2009-052A / 2009-052B <ref name="Display1">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2009-052A|title=Display: STSS Demo-1 2009-052A|publisher=NASA|date=14 May 2020|access-date=25 December 2020}} {{PD-notice}}</ref><ref name="Display2">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2009-052B|title=Display: STSS Demo-2 2009-052B|publisher=NASA|date=14 May 2020|access-date=25 December 2020}} {{PD-notice}}</ref> | SATCAT = 35937 / 35938 | mission_duration = Planned: 2 years<br />Final: 12 years, 2 months

| spacecraft = STSS | spacecraft_type = STSS demonstrator satellite | manufacturer = Northrop Grumman Space Technology | launch_mass = | dimensions = | power =

| launch_date = 25 September 2009,<br />12:20:00 UTC | launch_rocket = Delta II 7920-10C<br />(Delta D344) | launch_site = Cape Canaveral, LC-17B | launch_contractor = United Launch Alliance

| entered_service = Late January 2010 | disposal_type = | deactivated = 8 March 2022

| orbit_reference = Geocentric orbit<ref name="MDA"/> | orbit_regime = Low Earth orbit | orbit_altitude = {{cvt|1350|km}} | orbit_inclination = 58.0° | orbit_period = 120.0 minutes | apsis = gee }}

The '''Space Tracking and Surveillance System''' ('''STSS'''; formerly '''SBIRS-Low''') was a pair of satellites developed by the United States Missile Defense Agency (MDA) to research the space-based detection and tracking of ballistic missiles. Data from STSS satellites could allow interceptors to engage incoming missiles earlier in flight than would be possible with other missile detection systems.<ref>{{cite web|url=http://www.mda.mil/mdalink/html/sensors.html|title=MDA Link - Sensors|publisher=MDA|url-status=dead |archiveurl=https://web.archive.org/web/20080323085032/http://www.mda.mil/mdalink/html/sensors.html|archive-date=2008-03-23}} {{PD-notice}}</ref> The STSS program began in 2001, when the "SBIRS Low" program was transferred to MDA from the United States Air Force.<ref>{{cite web|url=http://www.cdi.org/friendlyversion/printversion.cfm?documentID=4122|title=Fact Sheet on Space Based Infrared System|year=2007|publisher=Center for Defense Information|url-status=dead|archiveurl=https://web.archive.org/web/20071113202652/http://www.cdi.org/friendlyversion/printversion.cfm?documentID=4122 |archive-date=2007-11-13}}</ref> In December 2002, SBIRS Low Research & Development (SBIRS Low R&D) was renamed Space Tracking and Surveillance System (STSS).<ref name="GS">{{cite web |url=https://www.globalsecurity.org/space/systems/stss.htm|title=Space Tracking and Surveillance System (STSS)|publisher=Global Security|access-date=25 December 2020}}</ref>

== Launch == One of the two satellites had been shipped to Cape Canaveral (CCAFS) on 4 May 2009; the second satellite arrived at the launch site on 25 June 2009.<ref>{{cite web |url=http://www.asd-network.com/press_detail/20361/STSS%27s_Demo_Program_Space_Vehicle_Two_Ships_to_Canaveral.htm|title=STSS's Demo Program Space Vehicle Two Ships to Canaveral|date=May 4, 2009|publisher=ASD Network}}</ref><ref>{{cite web|url=http://www.mda.mil/mdalink/pdf/09fyi0003.pdf|title=Space Tracking Surveillance System's Demonstration Program Ships Second Satellite to Cape Canaveral|date=7 July 2009 |publisher=Missile Defense Agency|access-date=21 August 2009|url-status=dead|archiveurl=https://web.archive.org/web/20090713124410/http://www.mda.mil/mdalink/pdf/09fyi0003.pdf|archive-date=13 July 2009}} {{PD-notice}}</ref>

Two demonstration satellites were launched together on a single Delta II launch vehicle.<ref>{{cite web|url=http://www.mda.mil/mdalink/pdf/stss06.pdf|title=Fact Sheet - Space Tracking and Surveillance System|publisher=MDA|year=2008|url-status=dead|archiveurl=https://web.archive.org/web/20090109013645/http://www.mda.mil/mdalink/pdf/stss06.pdf|archive-date=2009-01-09}} {{PD-notice}}</ref> Launch took place 25 September 2009, from Cape Canaveral Space Launch Complex 17 (LC-17B).<ref>{{cite web|url=http://www.nasa.gov/centers/kennedy/news/releases/2009/release-20090925.html|title=Delta II NASA Launch for Missile Defense Agency Successful|publisher=NASA KSC|date=September 25, 2009}} {{PD-notice}}</ref> STSS constellation consists of two satellites orbiting at 1350&nbsp;km, 58.0° inclination, with 120 minute period.<ref name="MDA">{{cite web|url=https://www.mda.mil/global/documents/pdf/stss.pdf|title=MDA Documents|publisher=MDA|date=27 March 2017}} {{PD-notice}}</ref>

It was reported that several items of debris,<ref>{{cite web|url=http://en.news.mn/news/4464|title=Object from sky most likely a dead satellite|date=31 December 2016}}</ref><ref>{{cite web |url=http://www.mk.ru/science/article/2010/02/25/437154-na-mongoliyu-upali-dva-nlo-foto.html|title=На Монголию упали два НЛО. ФОТО|date=25 February 2010 }}</ref> identified by amateur satellite watchers as remnants of the Delta-2 launch vehicle, had crashed in a field in Mongolia on 19 February 2010.<ref>{{cite web|url=http://www.satobs.org/seesat/Feb-2010/0238.html|title=Pieces of 09052C landed in Mongolia}}</ref>

== Early detection == The perceived advantage of STSS was that its satellites, by operating at a lower altitude and by using long- and short-wave infrared sensors, would be able to acquire and track missiles in midcourse and during the boost phase.<ref>{{cite web|url=http://www.afspc.af.mil/library/factsheets/factsheet.asp?id=3675|title=Fact Sheets - Space Based Infrared Systems|publisher=USAF|url-status=dead |archiveurl=https://web.archive.org/web/20070702032159/http://www.afspc.af.mil/library/factsheets/factsheet.asp?id=3675|archive-date=2007-07-02}} {{PD-notice}}</ref>

== The role of STSS == STSS was designed to be the low Earth orbiter (LEO) within the layered Ballistic Missile Defense System. It complemented the geosynchronous Defense Support Program, the Space-Based Infrared System, and other overhead non-imaging infrared (ONIR) systems<ref>[http://nsarchive.gwu.edu/NSAEBB/NSAEBB235/42.pdf Office of Secretary of Defense (Mar 2005) "Report to the Defense and Intelligence Committees of the Congress of the United States on the Status of the Space-Based Infrared System Program"] {{PD-notice}}</ref><ref>[http://www.globalsecurity.org/intell/systems/onir.htm ONIR systems]</ref> and provided tracking cues to systems on the surface. The STSS program was developed in phases, the first of which was the launch of two demonstrator satellites. The demonstrators performed experiments and proved out systems and processes to establish a knowledge base for future operational designs.<ref>{{cite web|url=http://www.aero.org/publications/crosslink/spring2008/03.html|title=The Missile Defense Agency's Space Tracking and Surveillance System|publisher=Aerospace Corporation}}</ref> The demonstration satellites, built by Northrop Grumman Space Technology (spacecraft) and Raytheon Technologies (sensors) detected and tracked a two-stage Ground-Based Interceptor (GBI) during a U.S. Missile Defense Agency flight test on 6 June 2010.<ref>{{cite web | url=http://www.irconnect.com/noc/press/pages/news_releases.html?d=195917 | title=IRconnect }}</ref>

== Congressional testimony == According to Congressional testimony, military officials believed that STSS had the potential to bolster the nation's missile defense system. "Two recent flight tests demonstrated that STSS dramatically improved the precision of threat missile attacks and provided more accurate fire control quality data to the Aegis ships several minutes earlier than less accurate data provided by organic radars in the Aegis or THAAD (Theater High Altitude Area Defense) systems", U.S. Army Lt. General Patrick J. O'Reilly, Director of the U.S. Missile Defense Agency, told the U.S. Senate Appropriations Committee's Defense subcommittee in prepared testimony on 25 May 2011.<ref>{{cite web|url=http://www.mda.mil/global/documents/pdf/PS_SAC-D_Hearing.LTG_O'Reilly.25_MAY_2011.pdf|title=Unclassified Statement of Lieutenant General Patrick J. O'Reilly, USA, Director, Missile Defense Agency Before the Senate Appropriations Committee Defense Subcommittee|access-date=2011-08-18|url-status=dead|archiveurl=https://web.archive.org/web/20111202231100/http://www.mda.mil/global/documents/pdf/PS_SAC-D_Hearing.LTG_O'Reilly.25_MAY_2011.pdf|archive-date=2011-12-02}}</ref>

== Timeline of STSS missile tracking tests == According to Globe Newswire (sourced by Northrop Grumman) press releases, the following is a summary of the STSS Demonstration program satellites' on-orbit performance.<ref>{{cite web |url=http://www.globenewswire.com/newsroom/news.html?d=209096|title=Northrop Grumman-Built STSS Demonstration Satellites Show 'Force Multiplier' Capability in Aegis Campaign Test|work=Northrop Grumman |publisher=Globe Newswire}}</ref><ref>{{cite web|url=http://www.globenewswire.com/newsroom/news.html?d=218435|title=Northrop Grumman-Built STSS Demonstrators Prove They Can Track Ballistic Missiles From 'Birth-to-Death'|work=Northrop Grumman|publisher=Globe Newswire}}</ref><ref>{{cite web|url=http://www.globenewswire.com/newsroom/news.html?d=225914|title=STSS Demonstration Satellites, Built by Northrop Grumman, Show New 'Remote Cueing' Capabilities During Aegis Test|work=Northrop Grumman|publisher=Globe Newswire}}</ref><ref>{{cite web|url=http://www.globenewswire.com/newsroom/news.html?d=226850|title=STSS Demonstrator Satellites, Built by Northrop Grumman, Track Short-Range, Air-Launched Rocket in Missile Defense Test|work=Northrop Grumman|publisher=Globe Newswire}}</ref>

'''June 2010''' * 6 June 2010 at 22:25 UTC Ground-Based Interceptor test launched from Vandenberg Air Force Base.

First STSS Object Sighting Messages (OSM) of a missile<br /> First on-board missile track formed.

* 16 June 2010 at 10:01 UTC ICBM Minuteman III test launched from Vandenberg Air Force Base<br /> Pre-determined target launched of Ronald Reagan Ballistic Missile Defense Test Site at Kwajalein Atoll, Marshall Islands<br /> Data transmitted at Missile Defense Integration and Operations Center (MDIOC) at Schriever Air Force Base, Colorado.

First dual satellite collect of target, and<br /> First target acquisition from a target launched beyond the horizon.

* 29 June 2010 at 07:32 UTC Scud missile was launched from a Mobile Launch Platform (formerly USS Tripoli) near of Kauai, Hawaii<br /> Terminal High Altitude Area Defense (THAAD) missile launched from Vandenberg Air Force Base.

First OSMs sent to Enterprise Sensors Laboratory at Schriever Air Force Base, Colorado, for data fusion with other sensors in real time<br /> First track of a dim theater missile.

'''July 2010''' * 19 July 2010 First track of a resident space object.

Tracked a NOAA weather satellite on 19 July 2010 for several minutes (externally queued)

* 23 July 2010 First autonomous acquisition sensor to track sensor handover of a target.

Hand-off demonstration occurred when STSS acquired a ground laser source operated by U.S. Air Force Research Laboratory from the Starfire Optical Range at Kirtland Air Force Base, New Mexico.

'''August 2010''' * 5 August 2010 First track of an aircraft

Precision track sensor operation below the horizon during daylight<br /> First autonomous acquisition sensor to track sensor handover of an aircraft

'''September 2010''' * 1 September 2010 Airborne Laser Test Bed Exercise

First autonomous acquisition sensor to track sensor handover of a boosted target

* 17 September 2020 at 10:02 UTC ICBM Minuteman III test launched from Vandenberg Air Force Base to Island of Guam (8500&nbsp;km).

First post boost track continuation of a target with track sensor<br /> First demonstration of track sensor generating multiple tracks for separating objects.

'''October 2010''' * 5 October 2010 Aegis Launch on Remote Campaign<br /> First Track sensor stereo track of a dim boosted target<br /> First stereo post boost tracking of midcourse target.

'''March 2011''' * 9 March 2011 Second Aegis Readiness Assessment Vehicle Targeting<br /> STSS satellites acquired and tracked its target until re-entry

* 15 March 2011 Second full-course tracking during U.S. Missile Defense Agency's (MDA) Aegis launch<br /> Successful production of "stereo" 3-D tracking software to follow the target missile's flight path to predict its impact point.

'''April 2011''' * 15 April 2011 Sea-based missile defense test

STSS satellites target and help to intercept an intermediate-range ballistic missile (IRBM); destruction of the IRBM on impact.

'''July 2011''' * 8 July 2011 STSS test on short-range air-launched target (SRALT)

This test proved the STSS's ability to track dim objects that have extremely short flight timelines.

== End of mission == The two Space Tracking and Surveillance System satellites stopped collecting data in September 2021. After being moved to higher orbits to prevent future collisions with other space objects, the two satellites were decommissioned on 8 March 2022.<ref>{{cite web |last=Erwin |first=Sandra |url=https://spacenews.com/dod-decommissions-two-missile-tracking-satellites-after-12-years-in-orbit/ |title=DoD decommissions two missile-tracking satellites after 12 years in orbit |work=SpaceNews |date=14 March 2022 |access-date=15 March 2022}}</ref>

== See also == {{Portal|Spaceflight}} * Aegis Ballistic Missile Defense System * Defense Support Program * Ground-Based Midcourse Defense * USA 205

== References == {{Reflist}}

== External links == * [http://www.zarya.info/Tracking/STSSDemo/STSSDemoMissileTests.php STSS Missile Tracking Demonstrations] * [http://www.heavens-above.com/orbit.aspx?satid=35937 STSS DEMO 1 (USA 208) - Orbit] * [http://www.heavens-above.com/orbit.aspx?satid=35938 STSS DEMO 2 (USA 209) - Orbit]

{{US Reconnaissance Satellites}} {{United States Missile Defense}}

Category:Missile defense Category:Early warning systems Category:Spacecraft launched in 2009 Category:Spacecraft decommissioned in 2022