Orbital Test Satellite
{{Use British English|date=April 2021}}
{{Use dmy dates|date=April 2021}}
{{Infobox spaceflight
| name = OTS 2
| names_list = Orbital Test Satellite
OTS
| image = Orbital Test Satellite - artist's impression.jpg
| image_caption = Artist's impression of the Orbital Test Satellite
| image_size = 300px
| mission_type = Technology demonstration,
Communications satellite
| operator = European Space Agency (ESA)
| COSPAR_ID = 1978-044A
| SATCAT = 10855
| website = http://www.esa.int/
| mission_duration = 3 years (planned)
{{time interval|11 May 1978|2 January 1991|show=ymd|sep=,}} (achieved)
| spacecraft = OTS 2
| spacecraft_type = OTS
| spacecraft_bus = OTS Bus
| manufacturer = British Aerospace (BAe) / Matra Marconi Space (MMS){{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1978-044A|title=Display: OTS 2 1978-044A|publisher=NASA|date=13 April 2021|access-date=18 April 2021}} {{PD-notice}}
| launch_mass = {{cvt|865|kg}}
| dry_mass = {{cvt|390|kg}}
| dimensions = {{cvt|2.4|xx|2.1|xx|1.7|m}}
Span: 9.3 m on orbit
| power = 600 watts
| launch_date = 11 May 1978, 22:59:00 UTC
| launch_rocket = Delta 3914 (s/n D141)
| launch_site = Cape Canaveral, LC-17A
| launch_contractor = McDonnell Douglas
| entered_service = July 1978
| disposal_type = Graveyard orbit
| deactivated = 2 January 1991
| last_contact =
| orbit_reference = Geocentric orbit
| orbit_regime = Geostationary orbit
| orbit_longitude = 10° East
| apsis = gee
| trans_band = 6 Ku-band
| trans_frequency =
| trans_bandwidth =
| trans_capacity =
| trans_coverage = Europe
| programme = OTS programme
| previous_mission = OTS-1
| next_mission =
}}
The Orbital Test Satellite (OTS) programme was an experimental satellite system inherited by the European Space Agency (ESA) in 1975 from its predecessor, the European Space Research Organisation (ESRO). OTS was the first three-axis-stabilised Ku-band satellite, and its design has inspired the conception of almost 30 other satellites in Europe. Its successors, the Maritime European Communications Satellite (MARECS) and European Communications Satellite (ECS) series of satellites, consolidated Europe's position in communications satellite technology and manufacturing.{{cite web|url=https://www.esa.int/esapub/br/br114/br114tel.htm|title=The Telecommunications Programme|publisher=ESA|date=August 1995|access-date=9 April 2021}}
OTS 1
The first of the pair of OTS satellites, OTS 1, was launched on 13 September 1977 at 11:31 pm UTC at the Cape Canaveral Space Launch Complex 17.{{cite web|title=ECS/OTS|url=http://www.astronautix.com/e/ecsots.html|archive-url=https://web.archive.org/web/20161228010329/http://astronautix.com/e/ecsots.html|url-status=dead|archive-date=28 December 2016|website=astronautix.com|access-date=17 October 2021}} However, it was destroyed 54 seconds later due to its United States Delta launcher exploding.{{R|sciencenews}} The failure was caused by a horizontal crack in the solid propellent core of one of the strap-on boosters, which caused the core gases to burn through the casing and ignite the fuel in the main tank of the launcher. The debris of the satellite landed in the Atlantic Ocean.{{cite web|title=Loss of the OTS 1 Satellite|url=https://satellitespy.net/blog/satellites/communication-satellites/loss-of-the-ots-1-satellite-918/|website=Satellite Spy|date=13 September 2012 |access-date=17 October 2021}}{{cite web|title=Display: OTS|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=OTS|website=NASA|access-date=17 October 2021}}{{cite journal|title=Experimenters prepare for tests with the first Orbital Test Satellite|url=https://ieeexplore.ieee.org/document/5184486|journal=Electronics and Power|year=1978 |publisher=IET|doi=10.1049/ep.1978.0246 |access-date=17 October 2021|last1=Golding |first1=J.E. |last2=Kernot |first2=R.J. |last3=Lewis |first3=J.R. |volume=24 |issue=6 |page=436 |url-access=subscription }}
OTS 2
OTS 2 was successfully launched on 11 May 1978 at 10:59 pm UTC at the same launch complex as OTS 1,{{cite web|title=Display trajectory: OTS 2 1978-044A|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1978-044A|website=NASA|access-date=17 October 2021}} using the same Delta launch vehicle. It became one of the first geostationary communications satellites to carry six Ku-band transponders and was capable of handling 7,200 telephone circuits. With a mass of approximately {{cvt|865|kg}}, the OTS satellite bus was hexagonal with overall dimensions of 2.4 by 2.1 x 1.7 m. Two solar panels with a span of 9.3 m provided 600 watts of electrical power.
British Aerospace was the prime contractor from the European MESH consortium which developed the satellite. It completed its primary mission in 1984 after which the spacecraft was involved in a 6-year program of experiments, including the testing of a new attitude control technique taking advantage of solar radiation pressure forces. In January 1991, OTS 2 was moved out of the geostationary ring and into a graveyard orbit.
References
{{Portal|Spaceflight}}
{{Reflist|30em|refs=
}}
Category:Communications satellites
Category:European Space Agency satellites
{{satellite-stub}}