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SpaceX reusable launch system development program

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The SpaceX reusable rocket launching system is a set of orbital launch system technologies being developed by SpaceX over a number of years in order to facilitate full and rapid reusability of space launch vehicles. The privately funded development effort aims to bring a launch vehicle first stage back to the launch site in minutes — and a second stage back to the launch pad, following orbital realignment with the launch site and atmospheric reentry, in up to 24 hours — with both stages designed to be available for reuse within "single-digit hours" after return.[1]

The design for "bringing the rocket back to launchpad using only thrusters" was completed in February 2012.[1] As of March 2013, SpaceX is in an active test program where they are testing both low-altitude, low-speed aspects of the landing technology, as well as testing high-speed, high-altitude aspects of the booster atmospheric return technology.

The reusable launch system technology is under consideration for both the Falcon 9 and the Falcon Heavy launch vehicles. It is particularly well suited to the Falcon Heavy where the two outer cores separate from the rocket much earlier in the flight profile, and are therefore moving at slower velocity at stage separation. If the technology is used on a reusable Falcon 9 rocket, the first stage separation would occur at Mach 6 (6,500 km/h; 4,000 mph)* rather than the much faster Mach 10 (11,100 km/h; 6,900 mph) for an expendable Falcon 9, in order to provide the residual fuel necessary to complete the deceleration and turnaround maneuver, as well as the controlled descent and landing.[1]

History

The broad outline of the reusable launch system was first announced on 29 September 2011. SpaceX indicated that they would attempt to develop powered descent and recovery of both Falcon 9 stages – a fully vertical takeoff, vertical landing (VTVL) rocket.[2] [3] Included was a video[4] said to be an approximation depicting the first stage returning tail-first for a powered descent and the second stage, with heat shield, reentering head first before rotating for a powered descent.[5] A reusable first stage is now being flight tested by SpaceX with the suborbital Grasshopper rocket.[6]

In May 2012, SpaceX received a re-entry database for the recovery of the Falcon 9 first stage based on 176 test runs in the NASA Marshall Space Flight Center wind tunnel test facility. The work was completed under a reimburseable Space Act Agreement.[7]

As of November 2012, CEO Elon Musk made public SpaceX has plans to build a second reusable rocket system, "an evolution of SpaceX's Falcon 9 booster ... much bigger [than Falcon 9], but I don’t think we’re quite ready to state the payload. We’ll speak about that next year. ... Vertical landing is an extremely important breakthrough — extreme, rapid reusability."[8]

By the end of 2012, the demonstration test vehicle, Grasshopper, had made three VTVL test flights including a 29-second hover flight to 40 metres (130 ft) on 17 Dec 2012.[6] In early March 2013, SpaceX successfully tested Grasshopper for a fourth time with a 24 story hop.

In March 2013, SpaceX announced that they would instrument and equip all subsequent Falcon 9 first-stages as controlled descent test vehicles, with plans to do over-water propulsively decelerated simulated landings beginning in mid-2013, with the intent to bring the vehicle back to the launch site for a powered landing, perhaps as early as mid-2014.[9][10]

The April 2013 draft Environmental Impact Statement for the proposed SpaceX private launch facility in south Texas includes specific accommodations for return of the Falcon 9 first-stage boosters to the launch site.[11] Elon Musk first publically referred to the reusable Falcon 9 as the "Falcon 9-R" in April 2013.[12]

Technologies

Several new technologies will need to be developed and tested to facilitate successful launch of the SpaceX reusable rocket launching system, including:

Test program

SpaceX has publically disclosed a multi-element test program that includes both low-altitude (less than 3.5 kilometres (11,500 ft)[14]), low-velocity testing of their Grasshopper technology-demonstrator at their Texas test site, as well as high-altitude (91 kilometres (300,000 ft),[15]) high-velocity (Mach 6 (6,700 km/h; 4,100 mph)[1]) ballistic reentry, controlled-deceleration and controlled-descent tests of post-mission (spent) Falcon 9 booster stages on Falcon 9 commercial missions beginning in mid-2013.

Grasshopper

Main article: Grasshopper (rocket)
 
Grasshopper vehicle in September 2012.

Grasshopper is an experimental technology-demonstrator, suborbital reusable launch vehicle (RLV), a vertical takeoff, vertical landing (VTVL) rocket[16] that was built in 2011/2012 for low-altitude testing that was scheduled to begin in 2012,[17] and did get underway in September 2012.[18] The initial test vehicle, Grasshopper version 1.0, "consists of a Falcon 9 first stage tank, a single Merlin-1D engine, four steel landing legs and a support structure, plus other pressurization tanks attached to the support structure"[13] and is 106 feet (32 m) tall.

SpaceX "constructed a half-acre concrete launch facility" to support the Grasshopper test flight program.[19]

Beginning in October 2012, SpaceX discussed development of a second-generation Grasshopper test vehicle, one that would have lighter-weight landing legs that fold up on the side of the rocket, would have a different engine bay, and would be nearly 50% longer than the first Grasshopper vehicle.[20] In March 2013, SpaceX announced that the Grasshopper v1.1 suborbital flight vehicle will be constructed out of the Falcon 9 v1.1 first-stage tank that was used for qualification testing at the SpaceX Rocket Development and Test Facility, McGregor, Texas, for the past several months. It will be rebuilt as the v1.1 Grasshopper "with flight-like landing legs."[15]

A multiphase, multiyear flight test program is underway for both Grasshopper test vehicles. The low-altitude, low-speed flights up to 3,500 metres (11,500 ft) altitude, for durations of up to 160 seconds (2.7 min), are being conducted at the SpaceX Test Facility in McGregor, Texas.[14][13] Test plans call for the v1.1 Grasshopper high-altitude test vehicle to be flight tested only at White Sands Missile Range, New Mexico, at altitudes up to approximately 91 kilometres (300,000 ft).[15]

SpaceX projected it would begin its flight test program in 2012,[17][19] and did so. Grasshopper began flight testing in September 2012 with a brief, three-second hop at the company's Texas test site,[18] followed by a second hop in November 2012 with an 8-second flight that took the testbed approximately 5.4 metres (18 ft) off the ground, and a third flight in December 2012 of 29 seconds duration, with extended hover under rocket engine power, in which it ascended to an altitude of 40 metres (130 ft).[6] A fourth test was successfully completed in March 2013, doubling its highest leap to rise to 80.1 metres (263 ft) with a 34 second duration.[21]

Falcon 9 booster post-mission, controlled-descent tests

Beginning with the first flight of the stretched version of the Falcon 9 launch vehicle—the sixth flight overall of Falcon 9, currently scheduled for June 2013—every first stage will be instrumented and equipped as a controlled descent test vehicle. SpaceX intends to do propulsive-return over-water tests and "will continue doing such tests until they can do a return to the launch site and a powered landing. ... They expect several failures before they 'learn how to do it right.'"[10] Since the tests will follow the normal launch mission Falcon 9 booster orbital-insertion flight path, the retro burn will occur at high-altitude and require initial deceleration from a velocity of approximately Mach 6 (6,700 km/h; 4,100 mph).[1]

The over-water tests will occur in both the Pacific and Atlantic oceans, south of Vandenberg Air Force Base and east of Cape Canaveral Air Force Station, respectively.

For the early-summer 2013 flight, after stage separation, the first stage booster will do a burn to slow it down and then a second burn just before it reaches the water. When the over-water test campaign is complete, SpaceX intends to begin to fly Falcon 9 boosters back to the launch site and land propulsively, perhaps starting as early as mid-2014.[9][10]

SpaceX has been explicit that they do not expect a successful recovery in the first several powered-descent tests. [9]

See also

References

  1. ^ a b c d e Simberg, Rand (2012-02-08). "Elon Musk on SpaceX's Reusable Rocket Plans". Popular Mechanics. Retrieved 2012-02-07.
  2. ^ "SpaceX chief details reusable rocket". Washington Post. 2011-09-30. Retrieved 2012-12-30. Both of the rocket's stages would return to the launch site and touch down vertically, under rocket power, on landing gear after delivering a spacecraft to orbit.
  3. ^ Wall, Mike (2011-09-30). "SpaceX Unveils Plan for World's First Fully Reusable Rocket". SPACE.com. Retrieved 2011-10-11.
  4. ^ http://www.spacex.com/assets/video/spacex-rtls-green.mp4
  5. ^ National Press Club: The Future of Human Spaceflight, cspan, 29 Sep 2011.
  6. ^ a b c Boyle, Alan (2012-12-24). "SpaceX launches its Grasshopper rocket on 12-story-high hop in Texas". MSNBC Cosmic Log. Retrieved 2012-12-25.
  7. ^ "NASA Finishes Wind-tunnel Testing of Falcon 9 1st Stage". Space News. 2012-05-28. {{cite news}}: |access-date= requires |url= (help)
  8. ^ Coppinger, Rod (2012-11-23). "Huge Mars Colony Eyed by SpaceX Founder Elon Musk". Space.com. Retrieved 2012-11-25. '
  9. ^ a b c Messier, Doug (2013-03-28). "Dragon Post-Mission Press Conference Notes". Parabolic Arc. Retrieved 2013-03-30. Q. What is strategy on booster recover? Musk: Initial recovery test will be a water landing. First stage continue in ballistic arc and execute a velocity reduction burn before it enters atmosphere to lessen impact. Right before splashdown, will light up the engine again. Emphasizes that we don't expect success in the first several attempts. Hopefully next year with more experience and data, we should be able to return the first stage to the launch site and do a propulsion landing on land using legs. Q. Is there a flight identified for return to launch site of the booster? Musk: No. Will probably be the middle of next year.
  10. ^ a b c Lindsey, Clark (2013-03-28). "SpaceX moving quickly towards fly-back first stage". NewSpace Watch. Retrieved 2013-03-29.
  11. ^ Nield, George C. (2014). Draft Environmental Impact Statement: SpaceX Texas Launch Site (Report). Vol. 1. Federal Aviation Administration, Office of Commercial Space Transportation. {{cite report}}: Unknown parameter |month= ignored (help)
  12. ^ a b First test of the Falcon 9-R (reusable) ignition system], 28 April 2013
  13. ^ a b c Mohney, Doug (2011-09-26). "SpaceX Plans to Test Reusable Suborbital VTVL Rocket in Texas". Satellite Spotlight. Retrieved 2011-11-23.
  14. ^ a b "Draft Environmental Assessment for Issuing an Experimental Permit to SpaceX for Operation of the Grasshopper Vehicle at the McGregor Test Site, Texas" (PDF). Federal Aviation Administration. 2011. Retrieved 2011-11-24.
  15. ^ a b c "Spacex May try to "land / recover" the first stage of it next Falcon 9 v1.1 launch this summer". Next Big Future. 2013-03-23. Retrieved 2013-04-06.
  16. ^ Klotz, Irene (2011-09-27). "A rocket that lifts off — and lands — on launch pad". MSNBC. Retrieved 2011-11-23.
  17. ^ a b Lindsey, Clark (2011-10-12). "Grasshopper news". RLV and Space Transport News. Retrieved 2011-11-23.
  18. ^ a b Clark, Stephen (2012-09-24). "SpaceX's reusable rocket testbed takes first hop". Spaceflightnow. Retrieved 2012-09-25.
  19. ^ a b "Reusable rocket prototype almost ready for first liftoff". Spaceflight Now. 2012-07-09. Retrieved 2012-07-13. SpaceX has constructed a half-acre concrete launch facility in McGregor, and the Grasshopper rocket is already standing on the pad, outfitted with four insect-like silver landing legs.
  20. ^ "A 2nd-gen Grasshopper + A new video of first hop". NewSpace Watch. 2012-10-02. Retrieved 2012-11-04.
  21. ^ "GRASSHOPPER COMPLETES HIGHEST LEAP TO DATE". SpaceX. 2013-03-10. Retrieved 2013-04-21.
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