Grasshopper is an experimental technology-demonstrator, suborbital reusable launch vehicle (RLV), a vertical takeoff, vertical landing (VTVL) rocket, built to support development and test of a subset of the technologies required for the SpaceX reusable rocket launching system. Grasshopper was announced in 2011 and began low-altitude, low-velocity hover/landing testing in 2012. A second Grasshopper test vehicle, larger and more capable, is currently being built and will be used for testing at higher altitudes and supersonic speeds.
Grasshopper is being developed and tested by Space Exploration Technologies (SpaceX) in order to assist development of the reusable Falcon 9 and reusable Falcon Heavy rockets, which will require vertical landings of the near-empty Falcon 9 and Falcon Heavy first-stage booster tanks and engine assemblies.
Grasshopper is one element of the multi-element SpaceX reusable rocket launching system test program, a program that includes both low-altitude, low-speed testing of the Grasshopper vehicle at the SpaceX Texas test site, as well as high-altitude, high-speed controlled-descent tests of post-mission (spent) Falcon 9 booster stages on Falcon 9 commercial missions beginning in mid-2013.
The Grasshopper technology demonstrator first became known publicly in the third-quarter of 2011, when space journalists first wrote about it after analyzing US government space launch regulatory documents.
Shortly thereafter, SpaceX confirmed the existence of the test vehicle development program, and projected it would begin the Grasshopper flight test program in 2012 and, in the event, did so. Grasshopper began flight testing in September 2012 with a brief, three-second hop at the company's Texas test site, 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) before descending under rocket power to come to a successful vertical landing. The flight test program is continuing in 2013.
In February 2012, SpaceX announced that they were planning several vertical-takeoff, vertical-landing (VTVL) test flights during 2012 and would "hopefully go supersonic in the fourth quarter." SpaceX did not disclose other details on the Grasshopper launch plans at the time, but CEO Elon Musk did indicate that some high-altitude tests may be staged from White Sands Missile Range, New Mexico. The location of the supersonic flight tests was unclear until May 2013; early on they were reported to possibly occur at White Sands Missile Range, New Mexico, or at the McGregor, Texas location, but no firm details had been announced.
SpaceX announced in June 2012 that they anticipated making the first test flight "in the next couple of months". Updated photos of the rocket on the test pad appeared in a news article on 11 Sep 2012, and the flight test program began on 21 Sep 2012.
Beginning in October 2012, SpaceX discussed development of a second generation Grasshopper test VTVL 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. In May 2013, they announced that the higher-altitude, higher-velocity part of the Grasshopper flight test program would be done at Spaceport America—and not at the Federal Government's adjacent White Sands Missile Range facility as previously planned—near Las Cruces, New Mexico, and signed a three-year lease for land and facilities at the recently-operational spaceport. SpaceX also announced in May that they had completed the Grasshopper low-altitude testing, and that they do not yet know how many jobs will move from McGregor, Texas to New Mexico.
Two versions of the Grasshopper test vehicle are under development, the 106-foot tall Grasshopper v1.0 and the 160-foot tall Grasshopper v1.1.
When Grasshopper was first disclosed in September 2011, the rocket was described to consist 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" and will stand at 106 feet (32 m) tall. Photos released in September 2012 reveal the test article landing gear to be considerably more sophisticated, with the tank and rocket engine as previously described.
In October 2012, SpaceX indicated that a second Grasshopper vehicle with fold-up landing legs would be built on the longer Falcon 9 v1.1 platform. As of March 2013[update], the v1.1 Grasshopper suborbital flight vehicle will be constructed out of the Falcon 9 v1.1 first-stage tank that has been used for qualification testing in Texas at the SpaceX Rocket Development and Test Facility for the past several months. It will be rebuilt as the next Grasshopper "with flight-like landing legs." In May 2013, the design for the retractable landing leg was shown to be a telescoping piston on an A-frame. The total span of the four legs will be approximately 18 metres (60 ft), and the landing gear will weigh less than 2,100 kilograms (4,600 lb); the deployment system will use high-pressure Helium.
Flight test program
Flight tests will include subsonic and supersonic testing.
Releases of public information in 2011 indicated that the subsonic tests would occur at SpaceX McGregor, Texas facility in three phases, at maximum flight altitudes of 670 to 11,500 feet (200 to 3,500 m), for durations of 45 to 160 seconds (0.75 to 2.7 min). At the time, testing was expected to take up to three years and the initial FAA permit allows up to 70 suborbital launches per year. SpaceX has "constructed a half-acre concrete launch facility" to support the test flight program. In September 2012, SpaceX announced that they have requested FAA approval to increase the altitude of some of the initial test flights.
Looking forward to the next year, CEO Musk said in November 2012: "Over the next few months, we’ll gradually increase the altitude and speed. ... I do think there probably will be some craters along the way; we’ll be very lucky if there are no craters. Vertical landing is an extremely important breakthrough — extreme, rapid reusability." Then in March 2013 Musk said that SpaceX hoped to reach hypersonic speed before the end of 2013. In May 2013, SpaceX moved the location of the higher-altitude, higher-velocity flight testing to Spaceport America, from the previous plan to do that testing at White Sands Missile Range.
Several test phases have been identified by SpaceX:
phase 1: The goal of Phase 1 is to verify the Grasshopper RLV’s overall ability to perform a VTVL mission. During a Phase 1 test, the Grasshopper RLV would be launched and ascend to 240 feet AGL and then throttle down in order to descend, landing back on the pad approximately 45 seconds after liftoff.
phase 2: There would be slightly less propellant loaded, a different thrust profile, and the maximum altitude would be increased to 670 feet , still below Class E Airspace. The mission duration during Phase 2 is again approximately 45 seconds.
phase 3: The goal of Phase 3—as outlined in the FAA documents for the McGregor, Texas location—is to verify the Grasshopper RLV’s ability to perform a VTVL mission at higher altitudes and higher ascent speeds and descent speeds. To achieve this, the maximum mission altitude, envisioned in the 2011 documents, would be increased from 670 feet incrementally up to 11,500 feet. The altitude test sequence likely would be 1,200 feet; 2,500 feet; 5,000 feet; 7,500 feet; and 11,500 feet. The maximum test duration would be approximately 160 seconds. The scope of the testing of Grasshopper v1.1 at the New Mexico Spaceport America facility has not yet been made public.
|Test #||Phase[original research?]||Date (year-month-day)||Highest altitude||Duration||Remarks|
|1||1||2012-09-21||6 feet (1.8 m)||3 seconds|
|2||1||2012-11-01||17.7 feet (5.4 m)||8 seconds|
|3||1||2012-12-17||131 feet (40 m)||29 seconds||First flight to include the cowboy mannequin|
|4||1||2013-03-07||262 feet (80 m)||34 seconds||Touchdown thrust-to-weight ratio greater than one|
|5||2||2013-04-17||820 feet (250 m)||61 seconds||Demonstrated ability to "hold against wind"|
|6||2013-06-14||1,066 feet (325 m)||Nearly 70 seconds|
Related over-water flight testing
In March 2013, SpaceX announced that, beginning with the first flight of the stretch version of the Falcon 9 launch vehicle—the sixth flight overall of Falcon 9, currently scheduled for later in 2013—every first stage would 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.'" For the first flight of the v1.1 Falcon 9 in 2013, after stage separation, the first stage booster will do a deceleration burn to slow it down and then a second burn just before it reaches the water. When all of the over-water testing is complete, they intend to fly back to the launch site and land propulsively, perhaps as early as mid-2014. 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.
SpaceX does not expect a successful booster recovery in the first several powered-descent tests.
|Wikimedia Commons has media related to: Grasshopper (rocket)|
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- Video of 1st test launch, 21 Sep 2012
- Video of 2nd test launch, 1 Nov 2012
- Video of 3rd test launch, 17 Dec 2012
- Video of 4th test launch, 8 Mar 2013
- Video of 5th test launch, to 250 m, c. 17 Apr 2013