Galileo - Revision history

Filipe.Pelica: Content duplicated on "Galileo Space Segment" article.

2014-07-07T10:44:33Z

Content duplicated on "Galileo Space Segment" article.

← Older revision		Revision as of 10:44, 7 July 2014
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	~~{{Article Infobox2~~		#REDIRECT [[Galileo General Introduction]]
	~~\|Category=GALILEO~~
	~~\|Authors=GMV~~
	~~\|Level=Basic~~
	~~\|YearOfPublication=2000~~
	~~\|Logo=ESA~~
	~~\|Title={{PAGENAME}}~~
	}}
	~~==Introduction==~~
	The Galileo Space Segment will comprise a constellation of a total of 30 Medium Earth Orbit (MEO) satellites, of which 3 are spares, in a so-called Walker 27/3/1 constellation<ref group="footnotes">A Walker Delta 56°:27/3/1 constellation, which means there are 27 satellites in 3 planes inclined at 56 degrees, spanning the 360 degrees around the equator.</ref>
	~~[[File:Galileo satellite system.jpg\|none\|thumb\|400px\|alt=Galileo satellite system\|Galileo satellite system]]~~

	~~Each satellite will broadcast precise time signals, ephemeris and other data. The Galileo satellite constellation has been optimised to the following nominal constellation specifications:~~
	* circular orbits (satellite altitude of 23 222 km)
	* orbital inclination of 56°
	* three equally spaced orbital planes
	* nine operational satellites, equally spaced in each plane
	* one spare satellite (also transmitting) in each plane

	~~The Galileo satellite is a 700 kg/1600 W class satellite.~~
	~~[[File:Galileo.jpg\|none\|thumb\|400px\|alt=Galileo\|Galileo]]~~

	The image shows an artist's impression of a Galileo spacecraft in orbit with solar arrays deployed. The spacecraft rotates about its Earth-pointing axis so that the flat surface of the solar arrays always faces the Sun to collect maximum solar energy. The antennas, shown on the underside of the body in the picture, always point towards the Earth. The spacecraft body will measure 2.7 m x 1.1 m x 1.2 m and the deployed solar arrays span 13 m.

	~~==Satellite components==~~
	~~The '''L-band antenna''' transmits the navigation signals in the 1200-1600 MHz frequency range.~~

	The '''[[Galileo Search and Rescue Service\|SAR (Search and Rescue)]]''' antenna picks up distress signals from beacons on Earth and transmits them to a ground station for forwarding to local rescue services.

	The '''C-band antenna''' receives signals containing mission data from Galileo Uplink Stations. This includes data to synchronise the on-board clocks with a ground-based reference clock and integrity data which contains information about how well each satellite is functioning. The integrity information is incorporated into the navigation signal for transmission to users.

	Two '''S-band antennas''' are part of the telemetry, tracking and command subsystem. They transmit housekeeping data about the payload and spacecraft to ground control and, in turn, receive commands to control the spacecraft and operate the payload. The S-band antennas also receive, process and transmit ranging signals that measure the satellite's altitude to within a few metres.

	The''' infrared Earth sensors''' and the '''Sun sensors''' both help to keep the spacecraft pointing at the Earth. The infrared Earth sensors do this by detecting the contrast between the cold of deep space and the heat of the Earth's atmosphere. The Sun sensors are visible light detectors which measure angles between their mounting base and incident sunlight.

	The '''laser retro-reflector''' allows the measurement of the satellite's altitude to within a few centimetres by reflecting a laser beam transmitted by a ground station. The laser retro-reflector is used only about once a year, as altitude measurements via S-band antenna ranging signals are otherwise accurate enough.

	The '''space radiators''' are heat exchangers that radiate waste heat, produced by the units inside the spacecraft, to deep space and thus help to keep the units within their operational temperature range.

	#REDIRECT [[Galileo ~~Space Segment]]~~

	~~== Interior: service module ==~~
	* '''SADM''' is the drive mechanism that connects the solar arrays to the spacecraft and rotates them slowly so that the surface of the arrays can remain perpendicular to the Sun's rays at all times.
	* The '''gyroscopes''' measure the rotation of the spacecraft.
	* The '''reaction wheels''' control the rotation of the spacecraft. When they rotate, so does the spacecraft. It rotates twice per orbit to allow the solar arrays to remain parallel to the Sun's rays.
	* The '''magneto bar''' modifies the speed of rotation of the reaction wheels by introducing a torque (turning force) in the opposite direction.
	* The '''power conditioning and distribution unit''' regulates and controls power from the solar arrays and batteries and distributes it to all the spacecraft's subsystems and payload.
	* The '''environmental monitoring unit''' on-board provides radiation measurements
	* The '''on-board computer''' controls all aspects of spacecraft and payload functioning.

	~~== Satellite facts and figures ==~~
	~~{\| class="wikitable"~~
	\|-
	~~! colspan="2" \| Spacecraft facts and figures~~
	\|-
	~~\|Spacecraft bus dimensions \|\| 2.7 x 1.1 x 1.2 m~~
	\|-
	~~\|Solar array span \|\| 13m~~
	\|-
	~~\|Peak power \|\| 1600 W~~
	\|-
	~~\|Navigation signals \|\| 10 signals transmitted in 1200-1600 MHz range~~
	\|-
	~~\|Launch mass \|\| 700kg~~
	\|}
	~~==Notes==~~
	~~<references group="footnotes"/>~~

	~~[[Category:GALILEO~~]]

Filipe.Pelica: Duplicated content

2014-07-07T10:40:55Z

Duplicated content

@@ Line 38: / Line 38: @@
 The '''space radiators''' are heat exchangers that radiate waste heat, produced by the units inside the spacecraft, to deep space and thus help to keep the units within their operational temperature range.
-== Interior: payload ==
+#REDIRECT [[Galileo Space Segment]]
 == Interior: service module ==

Filipe.Pelica at 16:22, 3 March 2014

2014-03-03T16:22:00Z

← Older revision		Revision as of 16:22, 3 March 2014
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	The '''L-band antenna''' transmits the navigation signals in the 1200-1600 MHz frequency range.		The '''L-band antenna''' transmits the navigation signals in the 1200-1600 MHz frequency range.

	The '''SAR (Search and Rescue)''' antenna picks up distress signals from beacons on Earth and transmits them to a ground station for forwarding to local rescue services.		The '''[[Galileo Search and Rescue Service\|SAR (Search and Rescue)]]''' antenna picks up distress signals from beacons on Earth and transmits them to a ground station for forwarding to local rescue services.

	The '''C-band antenna''' receives signals containing mission data from Galileo Uplink Stations. This includes data to synchronise the on-board clocks with a ground-based reference clock and integrity data which contains information about how well each satellite is functioning. The integrity information is incorporated into the navigation signal for transmission to users.		The '''C-band antenna''' receives signals containing mission data from Galileo Uplink Stations. This includes data to synchronise the on-board clocks with a ground-based reference clock and integrity data which contains information about how well each satellite is functioning. The integrity information is incorporated into the navigation signal for transmission to users.

Filipe.Pelica: footnotes harmonizing

2014-01-10T17:01:01Z

footnotes harmonizing

← Older revision		Revision as of 17:01, 10 January 2014
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	}}		}}
	==Introduction==		==Introduction==
	The Galileo Space Segment will comprise a constellation of a total of 30 Medium Earth Orbit (MEO) satellites, of which 3 are spares, in a so-called Walker 27/3/1 constellation<ref group="~~footnote~~">A Walker Delta 56°:27/3/1 constellation, which means there are 27 satellites in 3 planes inclined at 56 degrees, spanning the 360 degrees around the equator.</ref>		The Galileo Space Segment will comprise a constellation of a total of 30 Medium Earth Orbit (MEO) satellites, of which 3 are spares, in a so-called Walker 27/3/1 constellation<ref group="footnotes">A Walker Delta 56°:27/3/1 constellation, which means there are 27 satellites in 3 planes inclined at 56 degrees, spanning the 360 degrees around the equator.</ref>
	[[File:Galileo satellite system.jpg\|none\|thumb\|400px\|alt=Galileo satellite system\|Galileo satellite system]]		[[File:Galileo satellite system.jpg\|none\|thumb\|400px\|alt=Galileo satellite system\|Galileo satellite system]]

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	\|}		\|}
	==Notes==		==Notes==
	<references group="~~footnote~~"/>		<references group="footnotes"/>

	[[Category:GALILEO]]		[[Category:GALILEO]]

Filipe.Pelica: moved GALILEO to Galileo: Galileo is a name and not an acronym.

2014-01-09T18:27:10Z

moved GALILEO to Galileo: Galileo is a name and not an acronym.

← Older revision	Revision as of 18:27, 9 January 2014
(No difference)

Carlos.Lopez at 11:05, 23 February 2012

2012-02-23T11:05:04Z

← Older revision		Revision as of 11:05, 23 February 2012
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	{{Article Infobox2		{{Article Infobox2
	\|Category=GALILEO		\|Category=GALILEO
	~~\|Title={{PAGENAME}}~~
	\|Authors=GMV		\|Authors=GMV
	~~\|Logo=ESA~~
	\|Level=Basic		\|Level=Basic
	\|YearOfPublication=2000		\|YearOfPublication=2000
			\|Logo=ESA
			\|Title={{PAGENAME}}
	}}		}}
	==Introduction==		==Introduction==

Carlos.Lopez: /* Interior: service module */

2012-01-23T10:09:57Z

Interior: service module

← Older revision		Revision as of 10:09, 23 January 2012
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	* The '''magneto bar''' modifies the speed of rotation of the reaction wheels by introducing a torque (turning force) in the opposite direction.		* The '''magneto bar''' modifies the speed of rotation of the reaction wheels by introducing a torque (turning force) in the opposite direction.
	* The '''power conditioning and distribution unit''' regulates and controls power from the solar arrays and batteries and distributes it to all the spacecraft's subsystems and payload.		* The '''power conditioning and distribution unit''' regulates and controls power from the solar arrays and batteries and distributes it to all the spacecraft's subsystems and payload.
	* The '''environmental ~~Monitoring~~ unit''' on-board provides radiation measurements		* The '''environmental monitoring unit''' on-board provides radiation measurements
	* The '''on-board computer''' controls all aspects of spacecraft and payload functioning.		* The '''on-board computer''' controls all aspects of spacecraft and payload functioning.

Carlos.Lopez: /* Interior: service module */

2012-01-23T10:09:42Z

Interior: service module

← Older revision		Revision as of 10:09, 23 January 2012
Line 59:		Line 59:
	* The '''magneto bar''' modifies the speed of rotation of the reaction wheels by introducing a torque (turning force) in the opposite direction.		* The '''magneto bar''' modifies the speed of rotation of the reaction wheels by introducing a torque (turning force) in the opposite direction.
	* The '''power conditioning and distribution unit''' regulates and controls power from the solar arrays and batteries and distributes it to all the spacecraft's subsystems and payload.		* The '''power conditioning and distribution unit''' regulates and controls power from the solar arrays and batteries and distributes it to all the spacecraft's subsystems and payload.
			* The '''environmental Monitoring unit''' on-board provides radiation measurements
	* The '''on-board computer''' controls all aspects of spacecraft and payload functioning.		* The '''on-board computer''' controls all aspects of spacecraft and payload functioning.

	== Satellite facts and figures ==		== Satellite facts and figures ==
	{\| class="wikitable"		{\| class="wikitable"

Timo.Kouwenhoven: Text replace - "|Authors=Name." to "|Authors=GMV"

2011-11-01T14:04:44Z

Text replace - "|Authors=Name." to "|Authors=GMV"

← Older revision		Revision as of 14:04, 1 November 2011
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	\|Category=GALILEO		\|Category=GALILEO
	\|Title={{PAGENAME}}		\|Title={{PAGENAME}}
	\|Authors=~~Name.~~		\|Authors=GMV
	\|Logo=ESA		\|Logo=ESA
	\|Level=Basic		\|Level=Basic

Timo.Kouwenhoven: /* Interior: payload */

2011-02-20T14:03:16Z

Interior: payload

← Older revision		Revision as of 14:03, 20 February 2011
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	== Interior: payload ==		== Interior: payload ==
	A '''passive hydrogen maser clock''' is the master clock on board the spacecraft. It is an atomic clock which uses the ultra stable 1.4 GHz transition in a hydrogen atom to measure time to within 0.45 ns over 12 hours. A '''rubidium clock''' will be used should the maser clock fail. It is accurate to within 1.8 ns over 12 hours.		A '''passive hydrogen maser clock''' is the master clock on board the spacecraft. It is an atomic clock which uses the ultra stable 1.4 GHz transition in a hydrogen atom to measure time to within 0.45 ns over 12 hours.
			[[File:Passive hydrogen maser clock.jpg\|none\|thumb\|250px\|alt=passive hydrogen maser clock\|Passive hydrogen maser clock]]

			A '''rubidium clock''' will be used should the maser clock fail. It is accurate to within 1.8 ns over 12 hours.
	[[File:Rubidium clock.jpg\|none\|thumb\|250px\|alt=rubidium clock\|Rubidium clock]]		[[File:Rubidium clock.jpg\|none\|thumb\|250px\|alt=rubidium clock\|Rubidium clock]]