252:
not continue. Although the failed reaction wheels still function, they are experiencing friction exceeding acceptable levels, and consequently hindering the ability of the telescope to properly orient itself. The Kepler telescope was returned to its "point rest state", a stable configuration that uses small amounts of thruster fuel to compensate for the failed reaction wheels, while the Kepler team considered alternative uses for Kepler that do not require the extreme accuracy in its orientation needed by the original mission. On May 16, 2014, NASA extended the Kepler mission to a new mission named
298:. When mounted to a rigid spacecraft, applying a constant torque to the wheel using one of the gimbal motors causes the spacecraft to develop a constant angular velocity about a perpendicular axis, thus allowing control of the spacecraft's pointing direction. CMGs are generally able to produce larger sustained torques than RWs with less motor heating, and are preferentially used in larger or more-agile (or both) spacecraft, including
133:(better known as torque rods), which transfer angular momentum to the Earth through its planetary magnetic field requiring only electrical power and no fuel. They are however limited to areas of space with a sufficiently large magnetic field (such as in low Earth orbit). In the absence of a sufficiently strong magnetic field, the next most efficient practice is to use high-efficiency attitude jets such as
39:
31:
96:. Doing so alters the spacecraft's rotational dynamics so that disturbance torques perpendicular to one axis of the satellite (the axis parallel to the wheel's spin axis) do not result directly in spacecraft angular motion about the same axis as the disturbance torque; instead, they result in (generally smaller) angular motion (
251:
ability to maintain a sufficiently precise orientation to continue its original mission. On August 15, 2013, engineers concluded that Kepler's reaction wheels cannot be recovered and that planet-searching using the transit method (measuring changes in star brightness caused by orbiting planets) could
112:
For three-axis control, reaction wheels must be mounted along at least three directions, with extra wheels providing redundancy to the attitude control system. A redundant mounting configuration could consist of four wheels along tetrahedral axes, or a spare wheel carried in addition to a three axis
124:
Over time, reaction wheels may build up enough stored momentum to exceed the maximum speed of the wheel, called saturation. However, slowing down the wheels imparts a torque causing undesired rotation. Designers therefore supplement reaction wheel systems with other attitude control mechanisms to
100:) of that spacecraft axis about a perpendicular axis. This has the effect of tending to stabilize that spacecraft axis to point in a nearly-fixed direction, allowing for a less-complicated attitude control system. Satellites using this "momentum-bias" stabilization approach include
125:
cancel out the torque caused by "desaturating" the reaction wheels. Typically designers use "reaction control systems"; arrays of small chemical rocket engines that fire as the wheels slow down to counter the torque the wheels are imparting on the spacecraft as they slow down.
274:
to briefly delay its departure from Vesta's gravity until
September 5, 2012, and it planned to use thruster jets instead of the reaction wheels during the three-year journey to Ceres. The loss of the reaction wheels limited the camera observations on the approach to Ceres.
282:'s reaction wheels caused the mission control team to power off the suspected wheel, putting the observatory in safe mode as a precaution. This was the first time a reaction wheel failed on Swift in 17 years. Swift resumed science operations on February 17, 2022.
217:) replaced one after 'electrical anomalies', rather than any mechanical problem. Study of the returned mechanism provided a rare opportunity to study equipment that had undergone long-term service (seven years) in space, particularly for the effects of vacuum on
113:
configuration. Changes in speed (in either direction) are controlled electronically by computer. The strength of the materials used in a reaction wheel determine the speed at which the wheel would come apart, and therefore how much angular momentum it can store.
128:
More fuel efficient methods for reaction wheel desaturation have been developed over time. By reducing the amount of fuel the spacecraft needs to be launched with, they increase the useful payload that can be delivered to orbit. These methods include
269:
had excess friction in one reaction wheel in June 2010. It was originally scheduled to depart Vesta and begin its two-and-a-half-year journey to Ceres on August 26, 2012; however, a problem with another of the spacecraft's reaction wheels forced
193:
The failure of one or more reaction wheels can cause a spacecraft to lose its ability to maintain attitude (orientation) and thus potentially cause a mission failure. Recent studies conclude that these failures can be correlated with
116:
Since the reaction wheel is a small fraction of the spacecraft's total mass, easily controlled, temporary changes in its speed result in small changes in angle. The wheels therefore permit very precise changes in a spacecraft's
89:
needed for fuel.. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be rotated by very small amounts, such as keeping a telescope pointed at a star.
231:
replaced another reaction wheel. Neither of these wheels had failed and Hubble was designed with four redundant wheels, and maintained pointing ability so long as three were functional.
160:
technique to save fuel. Since its fourth maneuver in its elliptical orbit, to prevent shakes when the amount of liquid fuel ran low, there was a need to use a reaction wheel.
810:
931:
240:
spacecraft, an X-axis reaction wheel failed. The Y-axis wheel failed in 2005, causing the craft to rely on chemical thrusters to maintain attitude control.
861:
904:
674:
104:; by orienting the momentum wheel's axis to be parallel to the orbit-normal vector, this satellite is in a "pitch momentum bias" configuration.
92:
A reaction wheel is sometimes operated at a constant (or near-constant) rotation speed, to provide a satellite with a large amount of stored
499:
54:) is an electric motor attached to a flywheel, which, when its rotation speed is changed, causes a counter-rotation proportionately through
951:
511:
697:
294:(CMG) is a related but different type of attitude actuator, generally consisting of a momentum wheel mounted in a one-axis or two-axis
833:
260:. On October 30, 2018, NASA announced the end of the Kepler mission after it was determined that the fuel supply had been exhausted.
649:
398:
177:. LightSail 2 uses a reaction wheel system to change orientation by very small amounts, allowing it to receive different amounts of
771:
956:
482:
42:
A momentum/reaction wheel comprising part of a high-accuracy
Conical Earth Sensor to maintain a satellite's precise attitude
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618:
798:
307:
118:
74:
924:
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725:
865:
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Spacecraft
Gyroscopes And Reaction Wheels. You Can Never Have Enough | Fraser Cain | Universe Today | Aug, 2019
291:
546:
Astronauts replaced one of the four
Reaction Wheel Assemblies that make up Hubble's Pointing Control System.
325:
414:
221:. The lubricating compound was found to be in 'excellent condition'. In 2002, during Servicing Mission 3B (
253:
244:
226:
210:
541:
440:
886:
337:
63:
570:
561:
Carré, D. J.; Bertrand, P. A. (1999). "Analysis of Hubble Space
Telescope Reaction Wheel Lubricant".
526:
A Newly
Discovered Branch of the Fault Tree Explaining Systemic Reaction Wheel Failures And Anomalies
121:. For this reason, reaction wheels are often used to aim spacecraft carrying cameras or telescopes.
961:
157:
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198:
effects. These events probably caused failures by inducing electrostatic discharge in the steel
394:
319:
279:
265:
915:
578:
218:
93:
86:
55:
752:
675:"NASA Ends Attempts to Fully Recover Kepler Spacecraft, Potential New Missions Considered"
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905:"Enabling Reaction Wheel Technology for High Performance Nanosatellite Attitude Control"
574:
702:
59:
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195:
78:
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134:
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have replaced a reaction wheel. In
February 1997, the Second Servicing Mission (
923:
Markley, F. Landis; Reid G. Reynolds; Frank X. Liu; Kenneth L. Lebsock (2009).
358:
38:
30:
278:
On the evening of
Tuesday, January 18, 2022, a possible failure of one of the
257:
174:
97:
70:
17:
626:
328: – Spacecraft thrusters used to provide attitude control and translation
730:
653:
170:
145:
243:
From July 2012 to May 11, 2013, two out of the four reaction wheels in the
256:, which uses Kepler differently, but allows it to continue searching for
236:
178:
149:
101:
512:"crowdfunded-spacecraft-lightsail-2-prepares-to-go-sailing-on-sunlight"
222:
805:. NASA Official: Brian Dunbar; Image credit(s): NASA Ames/W. Stenzel.
299:
295:
214:
203:
152:
rocket on 22 February 2019 1:45 UTC, with the goal of landing on the
82:
753:"Kepler: NASA retires prolific telescope from planet-hunting duties"
650:"Planet-Hunting Kepler Spacecraft Suffers Major Failure, NASA Says"
582:
834:"NASA Retires Kepler Space Telescope, Passes Planet-Hunting Torch"
331:
182:
37:
29:
925:"Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays"
806:
622:
153:
167:
has six reaction wheels built by
Rockwell Collins Deutschland.
303:
173:
was launched on 25 June 2019, focused around the concept of a
726:"Planet-Hunting Days of NASA's Kepler Spacecraft Likely Over"
889:
NASA News, February 18, 2022, NASA. Retrieved April 16, 2023
864:. NASA / Jet Propulsion Laboratory. Archived from
903:
Sinclair, Doug; Grant, C. Cordell; Zee, Robert E. (2007).
542:"Team Hubble: Servicing Missions -- Servicing Mission 3B"
62:; it is not capable of moving from one place to another (
797:
Sobeck, Charlie (May 16, 2014). Johnson, Michele (ed.).
556:
554:
799:"Kepler Mission Manager Update: K2 Has Been Approved!"
772:"Kepler Mission Manager Update: Pointing Test Results"
206:
wheels, compromising the smoothness of the mechanism.
417:. Universität Stuttgart Institut für Raumfahrtsysteme
698:"NASA's Kepler Mended, but May Never Fully Recover"
887:NASA's NASA's Swift Observatory Returns to Science
536:
534:
389:Wiley J Larson and James R Wertz (January 1999).
185:across the sail, resulting in a higher altitude.
855:
853:
483:"spaceil-conducts-another-successful-maneuver"
58:. A reaction wheel can rotate only around its
8:
465:"israels-moon-mission-launched-successfully"
340: – Method used to accelerate spacecraft
247:failed. This loss severely affected Kepler
27:Attitude control device used in spacecraft
34:A small reaction wheel viewed in profile
350:
862:"Dawn Engineers Assess Reaction Wheel"
384:
382:
380:
378:
376:
69:Reaction wheels are used primarily by
7:
916:"Reaction Wheel at Wolfram Research"
860:Cook, Jia-Rui C. (August 18, 2012).
434:
432:
696:Overbye, Dennis (August 15, 2013).
234:In 2004, during the mission of the
25:
813:from the original on May 17, 2014
563:Journal of Spacecraft and Rockets
391:Space Mission Analysis and Design
334: – Satellite X-ray telescope
937:from the original on 2022-10-09.
56:conservation of angular momentum
393:(3 ed.). Microcosm Press.
225:), astronauts from the shuttle
724:Wall, Mike (August 15, 2013).
322: – Aerospace manufacturer
209:Two servicing missions to the
1:
832:Chou, Felicia (2018-10-30).
952:Spacecraft attitude control
308:International Space Station
189:Failures and mission impact
81:or external applicators of
980:
648:Mike Wall (May 15, 2013).
165:James Webb Space Telescope
359:"Reaction/Momentum Wheel"
292:control moment gyroscope
524:W. Bialke, E. Hansell "
326:Reaction control system
245:Kepler space telescope
211:Hubble Space Telescope
43:
35:
957:Spacecraft propulsion
338:Spacecraft propulsion
263:The NASA space probe
156:. Beresheet uses the
77:, and do not require
41:
33:
85:, which reduces the
575:1999JSpRo..36..109C
471:. 22 February 2019.
158:low-energy transfer
64:translational force
415:"Attitude Control"
148:was launched on a
44:
36:
868:on March 15, 2015
759:. 16 August 2013.
677:. August 15, 2013
441:"Control Devices"
320:Collins Aerospace
280:Swift Observatory
16:(Redirected from
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75:attitude control
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629:on June 1, 2013
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918:. June 2008.
882:
870:. Retrieved
866:the original
841:. Retrieved
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815:. Retrieved
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782:24 September
780:. Retrieved
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735:. Retrieved
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707:. Retrieved
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679:. Retrieved
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657:. Retrieved
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631:. Retrieved
627:the original
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601:. Retrieved
597:"Gyroscopes"
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872:January 22,
171:LightSail 2
962:Gyroscopes
946:Categories
843:2018-11-16
737:August 15,
709:August 15,
681:August 15,
619:"Hayabusa"
450:2024-01-12
345:References
306:, and the
258:exoplanets
219:lubricants
175:solar sail
98:precession
71:spacecraft
731:Space.com
654:Space.com
421:12 August
181:from the
146:Beresheet
932:Archived
811:Archived
803:nasa.gov
776:NASA.gov
757:BBC News
314:See also
237:Hayabusa
228:Columbia
179:momentum
150:Falcon 9
141:Examples
119:attitude
102:SCISAT-1
817:May 17,
659:May 15,
633:May 15,
603:8 April
571:Bibcode
528:", 2017
365:15 June
223:STS-109
79:rockets
778:. NASA
487:Globes
469:Globes
397:
361:. NASA
300:Skylab
296:gimbal
249:'s
215:STS-82
204:Ithaco
108:Design
83:torque
935:(PDF)
928:(PDF)
908:(PDF)
599:. ESA
332:ROSAT
183:light
874:2015
838:NASA
819:2014
807:NASA
784:2013
739:2013
711:2013
683:2013
661:2013
635:2013
623:NASA
605:2016
423:2016
395:ISBN
367:2018
272:Dawn
266:Dawn
163:The
154:Moon
579:doi
304:Mir
202:of
66:).
948::
930:.
852:^
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728:.
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621:.
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567:36
565:.
553:^
544:.
533:^
485:.
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443:.
431:^
375:^
310:.
302:,
290:A
254:K2
137:.
52:RW
46:A
910:.
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50:(
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