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Star 48

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Star 48
Star-48B rocket motor
Country of originUnited States
Date1982–present
ManufacturerThiokol
PredecessorStar 37
Solid-fuel motor

TheStar 48isthe largest of a familyofsolid rocketmotors used by many space propulsion and launch vehiclestages,almost exclusively as an upper stage. It was developed primarily byThiokol Propulsionand after several mergers, is manufactured byNorthrop Grumman’s Space Systems division. A Star 48B stage is also one ofthe few man-made items sent on escape trajectories out of the Solar System,although it isderelictsince its use. The Star 48B variant was thePAM-Dupper stage used on the retiredDelta IIrocket.

The Star 48 has been used as an upper stage in three- and four-stage launch systems.

In theMagellanVenus orbiter

Overview

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The "48" designation refers to the approximate diameter of the fuel casing in inches (122 cm); Thiokol had also manufactured other motors such as theStar 37and Star 30. Internally, Thiokol's designation was TE-M-711 for early versions and TE-M-799 for later ones. Subtypes are given one or more letter suffixes after the diameter number, or a trailing number (i.e., "-2" ) after the internal designation. The "T" prefix stands for Thiokol, and the following letter refers to the company division that developed the rocket motor. In this case, "E" refers to the Elkton, MD division, and the "M" stands for the motor.

The Star 48 holds 2,000 kg of propellant.

The most common use of the Star 48 was as the final stage of theDelta IIlaunch vehicles. Other launchers such asULA'sAtlas 551have also incorporated the motor but with lower frequency. On board theSpace Shuttle,the complete stage (motor plus accessories) was referred to as thePayload Assist Module(PAM), as the Shuttle could only take satellites tolow Earth orbit.Becausegeostationaryorbit is much more lucrative, the additional stage was needed for the final leg of the journey. On such missions, the stage wasspin-stabilized.A turntable, mounted in the shuttle payload bay or atop the previous Delta stage, spun the PAM and payload to approximately 60 rpm prior to release.

Usually after motor burnout and just prior to satellite release the PAM is de-spun using ayo-yo de-spintechnique.

Saudi inspectors at the crash site of a Star 48Payload Assist Modulein January 2001

A Star 48Payload Assist Modulethat had been used to launch anUSA-91GPS satellitein 1993 crashed in the Saudi Arabian desert in January 2001, after its orbit decayed. The unit did not burn up on reentry and was positively identified on the ground.[1]

A non-spinning,thrust-vectoringversion of the Star 48 is available ( "Star 48BV" ), but much less common. A thrust-vectoring Star 48 is the final stage of theMinotaur IV+launch vehicle.

In 2013 a Star 48GXV ( "G" for "graphite case" ) was tested for theSolar Probe Plusmission (which later was renamed to theParker Solar Probe)[2]but the development was cancelled, in favor of aDelta IV Heavy/ Star 48BV combination.[3]for the launch in 2018.[4][5]

A Star 48B motor (i.e. non-vectoring) used in the 3rd stage of theNew Horizonsprobe was the first part of theNew Horizonsmission to reachJupiter,arriving before the probe.[6]It also crossedPluto's orbit in 2015 at a distance of 200 million kilometers.

Star 48B

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The Star 48B version has an extra 11 kilograms of propellant more than the regular Star 48, for a total of 2011 kg.[7]There is a version of the Star 48B that is lengthened and also heavier, called the Star 48B L.[8]

In operation as a third stage, the Star 48B sits on top of the spin table, and before it is separated, it is spun up to stabilize it during the separation from the previous stage.[9](see alsospin-stabilisation) The Star 48B can produce 15,000 pounds of thrust (66723newtons), with a burn time of 1 minute 27 seconds.[10]

The Star 48B is the basis for theMcDonnell DouglasPAM-D upper stage used on the Delta rocket.[10]

Use onNew Horizons

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A Star 48B was used on the third stage of theNew Horizonsspacecraft launch.[11]New Horizonswas launched by ULA's Atlas V 551 in January 2006, and the Star 48B booster was launched along with theNew Horizons's spacecraft on an escape trajectory out of the Solar System.[12]The Star 48B ignited and burned for 48 seconds, taking both on a trajectory past Pluto; however, because the Star 48B became derelict and did not have course corrections like the NH spacecraft, it was projected to miss Pluto by hundreds of millions of miles.[12]

New Horizons'Star 48B was calculated to arrive atJupitersix hours beforeNew Horizons,and on October 15, 2015 passed through Pluto's orbit at a distance of 213 million kilometers (over 1au) distant fromPluto.[12][13]This was nearly four months after theNew Horizonsprobe did.[6]

Europa Clipper

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NASA intended to launch theEuropa Clipperusing a Star 48 on aSpaceXFalcon Heavy.The addition of a Star 48 "kick stage" would have allowed the Clipper mission to reachEuropawithout needing agravity assistfromVenus.[14]This was later removed with an updated Mars gravity assist route.[15]

See also

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References

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  1. ^"PAM-D Debris Falls in Saudi Arabia"(PDF).The Orbital Debris Quarterly News.6(2). NASAJohnson Space Center:1. April 2001. Archived fromthe original(PDF)on 2004-07-28.
  2. ^"ATK and NASA Successfully Demonstrate New Rocket Motor for Solar Probe Plus Mission".Prnewswire(Press release).
  3. ^"Orbital ATK to Augment ULA Rocket for Launch of NASA Solar Probe".ExecutiveBiz.Retrieved2017-02-12.
  4. ^Clark, Stephen (March 18, 2015)."Delta 4-Heavy selected for the launch of solar probe".Spaceflight Now.RetrievedMarch 18,2015.
  5. ^"ULA's heavy-lifter rolled out for solar probe launch – Spaceflight Now".spaceflightnow.Retrieved2018-11-05.
  6. ^ab"Derelict Booster to Beat Pluto Probe to Jupiter".Space.26 January 2006.
  7. ^"Star 48B".Astronautix.Archived fromthe originalon December 28, 2016.Retrieved2018-10-22.
  8. ^"Star 48B l".Astronautix.Archived fromthe originalon December 28, 2016.Retrieved2018-10-22.
  9. ^Michael J. Muolo (1993).Space Handbook: A War Fighter's Guide to Space, V. 1.Government Printing Office. p. 126.ISBN978-0-16-061355-5.
  10. ^ab"PAM-D Payload Assist Module Archives - This Day in Aviation".This Day in Aviation.Retrieved2018-10-22.
  11. ^"Press kit: NASA's First Mission to Pluto and the Kuiper Belt"(PDF).Nasa.gov.Retrieved22 October2018.
  12. ^abcStern, Alan; Guo, Yanping (October 28, 2010)."Where Is the New Horizons Centaur Stage?".Johns Hopkins University Applied Physics Laboratory.Retrieved2018-10-22.
  13. ^"New Horizons trajectory: Star 48b Third-stage Motor".Unmannedspaceflight.
  14. ^"SpaceX to launch the Europa Clipper mission for a bargain price".Arstechnica.23 July 2021.
  15. ^Brown, David."EUROPA CLIPPER INCHES FORWARD, SHACKLED TO THE EARTH".SuperCluster.Retrieved26 November2022.
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