241:
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
287:. 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
28:
20:
122:(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
85:. 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 (
240:
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
101:
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
113:
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
89:) 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
114:
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.
263:
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.
271:'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.
206:) 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
102:
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.
117:
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
258:
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
182:
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
105:
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
78:
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.
220:
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.
149:
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.
799:
920:
229:
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.
850:
893:
663:
93:; by orienting the momentum wheel's axis to be parallel to the orbit-normal vector, this satellite is in a "pitch momentum bias" configuration.
81:
A reaction wheel is sometimes operated at a constant (or near-constant) rotation speed, to provide a satellite with a large amount of stored
488:
43:) is an electric motor attached to a flywheel, which, when its rotation speed is changed, causes a counter-rotation proportionately through
500:
686:
283:(CMG) is a related but different type of attitude actuator, generally consisting of a momentum wheel mounted in a one-axis or two-axis
822:
249:. On October 30, 2018, NASA announced the end of the Kepler mission after it was determined that the fuel supply had been exhausted.
638:
166:. LightSail 2 uses a reaction wheel system to change orientation by very small amounts, allowing it to receive different amounts of
760:
471:
31:
A momentum/reaction wheel comprising part of a high-accuracy
Conical Earth Sensor to maintain a satellite's precise attitude
940:
453:
607:
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387:
242:
44:
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714:
945:
854:
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Spacecraft
Gyroscopes And Reaction Wheels. You Can Never Have Enough | Fraser Cain | Universe Today | Aug, 2019
535:
Astronauts replaced one of the four
Reaction Wheel Assemblies that make up Hubble's Pointing Control System.
403:
210:. The lubricating compound was found to be in 'excellent condition'. In 2002, during Servicing Mission 3B (
530:
429:
296:
107:
63:
875:
153:
550:
Carré, D. J.; Bertrand, P. A. (1999). "Analysis of Hubble Space
Telescope Reaction Wheel Lubricant".
515:
A Newly
Discovered Branch of the Fault Tree Explaining Systemic Reaction Wheel Failures And Anomalies
110:. For this reason, reaction wheels are often used to aim spacecraft carrying cameras or telescopes.
280:
314:
514:
187:
effects. These events probably caused failures by inducing electrostatic discharge in the steel
233:
215:
199:
904:
326:
52:
559:
741:
664:"NASA Ends Attempts to Fully Recover Kepler Spacecraft, Potential New Missions Considered"
585:
8:
950:
146:
894:"Enabling Reaction Wheel Technology for High Performance Nanosatellite Attitude Control"
563:
911:
383:
308:
268:
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567:
207:
82:
75:
159:
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have replaced a reaction wheel. In
February 1997, the Second Servicing Mission (
912:
Markley, F. Landis; Reid G. Reynolds; Frank X. Liu; Kenneth L. Lebsock (2009).
691:
347:
48:
267:
On the evening of
Tuesday, January 18, 2022, a possible failure of one of the
934:
615:
317: – Spacecraft thrusters used to provide attitude control and translation
184:
67:
232:
From July 2012 to May 11, 2013, two out of the four reaction wheels in the
188:
123:
119:
245:, which uses Kepler differently, but allows it to continue searching for
891:
501:"crowdfunded-spacecraft-lightsail-2-prepares-to-go-sailing-on-sunlight"
246:
163:
86:
59:
794:. NASA Official: Brian Dunbar; Image credit(s): NASA Ames/W. Stenzel.
719:
642:
141:
rocket on 22 February 2019 1:45 UTC, with the goal of landing on the
134:
742:"Kepler: NASA retires prolific telescope from planet-hunting duties"
639:"Planet-Hunting Kepler Spacecraft Suffers Major Failure, NASA Says"
571:
225:
167:
138:
90:
27:
19:
823:"NASA Retires Kepler Space Telescope, Passes Planet-Hunting Torch"
914:"Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays"
211:
377:
288:
284:
203:
192:
156:
has six reaction wheels built by
Rockwell Collins Deutschland.
71:
162:
was launched on 25 June 2019, focused around the concept of a
715:"Planet-Hunting Days of NASA's Kepler Spacecraft Likely Over"
320:
171:
878:
NASA News, February 18, 2022, NASA. Retrieved April 16, 2023
853:. NASA / Jet Propulsion Laboratory. Archived from
795:
611:
142:
892:
Sinclair, Doug; Grant, C. Cordell; Zee, Robert E. (2007).
531:"Team Hubble: Servicing Missions -- Servicing Mission 3B"
292:
51:; it is not capable of moving from one place to another (
786:
Sobeck, Charlie (May 16, 2014). Johnson, Michele (ed.).
545:
543:
788:"Kepler Mission Manager Update: K2 Has Been Approved!"
761:"Kepler Mission Manager Update: Pointing Test Results"
195:
wheels, compromising the smoothness of the mechanism.
540:
406:. Universität Stuttgart Institut für Raumfahrtsysteme
687:"NASA's Kepler Mended, but May Never Fully Recover"
876:NASA's NASA's Swift Observatory Returns to Science
525:
523:
378:Wiley J Larson and James R Wertz (January 1999).
174:across the sail, resulting in a higher altitude.
932:
844:
842:
520:
472:"spaceil-conducts-another-successful-maneuver"
177:
47:. A reaction wheel can rotate only around its
779:
656:
549:
839:
678:
454:"israels-moon-mission-launched-successfully"
329: – Method used to accelerate spacecraft
706:
236:failed. This loss severely affected Kepler
16:Attitude control device used in spacecraft
636:
427:
26:
23:A small reaction wheel viewed in profile
18:
684:
933:
851:"Dawn Engineers Assess Reaction Wheel"
785:
373:
371:
369:
367:
365:
58:Reaction wheels are used primarily by
905:"Reaction Wheel at Wolfram Research"
849:Cook, Jia-Rui C. (August 18, 2012).
848:
820:
712:
423:
421:
685:Overbye, Dennis (August 15, 2013).
362:
223:In 2004, during the mission of the
13:
758:
274:
14:
962:
885:
802:from the original on May 17, 2014
552:Journal of Spacecraft and Rockets
418:
380:Space Mission Analysis and Design
323: – Satellite X-ray telescope
926:from the original on 2022-10-09.
45:conservation of angular momentum
869:
814:
752:
734:
630:
600:
578:
382:(3 ed.). Microcosm Press.
214:), astronauts from the shuttle
713:Wall, Mike (August 15, 2013).
507:
493:
482:
464:
446:
396:
340:
311: – Aerospace manufacturer
198:Two servicing missions to the
1:
333:
821:Chou, Felicia (2018-10-30).
7:
941:Spacecraft attitude control
302:
297:International Space Station
178:Failures and mission impact
129:
70:or external applicators of
10:
967:
637:Mike Wall (May 15, 2013).
154:James Webb Space Telescope
348:"Reaction/Momentum Wheel"
96:
281:control moment gyroscope
513:W. Bialke, E. Hansell "
315:Reaction control system
234:Kepler space telescope
200:Hubble Space Telescope
32:
24:
946:Spacecraft propulsion
327:Spacecraft propulsion
252:The NASA space probe
145:. Beresheet uses the
66:, and do not require
30:
22:
74:, which reduces the
564:1999JSpRo..36..109C
460:. 22 February 2019.
147:low-energy transfer
53:translational force
404:"Attitude Control"
137:was launched on a
33:
25:
857:on March 15, 2015
748:. 16 August 2013.
666:. August 15, 2013
430:"Control Devices"
309:Collins Aerospace
269:Swift Observatory
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614:. Archived from
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478:. 19 March 2019.
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83:angular momentum
64:attitude control
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759:Hunter, Roger.
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618:on June 1, 2013
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503:. 21 June 2019.
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275:Similar devices
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62:for three-axis
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886:External links
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692:New York Times
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572:10.2514/2.3422
558:(1): 109–113.
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49:center of mass
37:reaction wheel
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185:space weather
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124:ion thrusters
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120:magnetorquers
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76:mass fraction
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29:
21:
907:. June 2008.
871:
859:. Retrieved
855:the original
830:. Retrieved
826:
816:
804:. Retrieved
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781:
771:24 September
769:. Retrieved
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736:
724:. Retrieved
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696:. Retrieved
690:
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668:. Retrieved
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646:. Retrieved
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620:. Retrieved
616:the original
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590:. Retrieved
586:"Gyroscopes"
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437:. Retrieved
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408:. Retrieved
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36:
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861:January 22,
160:LightSail 2
951:Gyroscopes
935:Categories
832:2018-11-16
726:August 15,
698:August 15,
670:August 15,
608:"Hayabusa"
439:2024-01-12
334:References
295:, and the
247:exoplanets
208:lubricants
164:solar sail
87:precession
60:spacecraft
720:Space.com
643:Space.com
410:12 August
170:from the
135:Beresheet
921:Archived
800:Archived
792:nasa.gov
765:NASA.gov
746:BBC News
303:See also
226:Hayabusa
217:Columbia
168:momentum
139:Falcon 9
130:Examples
108:attitude
91:SCISAT-1
806:May 17,
648:May 15,
622:May 15,
592:8 April
560:Bibcode
517:", 2017
354:15 June
212:STS-109
68:rockets
767:. NASA
476:Globes
458:Globes
386:
350:. NASA
289:Skylab
285:gimbal
238:'s
204:STS-82
193:Ithaco
97:Design
72:torque
924:(PDF)
917:(PDF)
897:(PDF)
588:. ESA
321:ROSAT
172:light
863:2015
827:NASA
808:2014
796:NASA
773:2013
728:2013
700:2013
672:2013
650:2013
624:2013
612:NASA
594:2016
412:2016
384:ISBN
356:2018
261:Dawn
255:Dawn
152:The
143:Moon
568:doi
293:Mir
191:of
55:).
937::
919:.
841:^
825:.
798:.
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763:.
744:.
717:.
689:.
641:.
610:.
566:.
556:36
554:.
542:^
533:.
522:^
474:.
456:.
432:.
420:^
364:^
299:.
291:,
279:A
243:K2
126:.
41:RW
35:A
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865:.
835:.
810:.
775:.
730:.
702:.
674:.
652:.
626:.
596:.
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562::
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392:.
358:.
39:(
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