National Aeronautics and Space Administration

A-1 Test Stand By any standard, the A-1 Test Stand at NASA’s Stennis Space Center is special.

Consider its durability. Built in the 1960s to test Saturn rocket stages that carried humans to the Moon, it has remained in active use for more than 50 years.

Consider its adaptability. After the Apollo Program, the stand was modified to test other engines, including those that powered flights for 30 years.

Consider its pedigree. Rocket stages and engines tested on the stand have carried humans to the Moon, powered historic space shuttle missions and tested engines that will launch the next great era of deep space exploration. facts Consider its record. No rocket stage or engine tested on the stand (or any of the large Stennis stands) has ever been the cause of a mission failure.

Consider, at last, its future. Modified once again, the stand now is testing RS-25 engines that will power NASA’s Moon-to-Mars missions aboard the new (SLS) vehicle.

It is no wonder the stand has been designated as a historic landmark – even as that history continues to be written.

n The A-1 Test Stand is a single-position, n A total of 1,007 space shuttle main engines vertical-firing facility, which means that the tests were conducted on the A-1 Test Stand, stand can accommodate only one rocket including the first-ever test of a shuttle main NASA engine/stage at a time and that engines/ engine on May 19, 1975. The final space stages are fired in an upright position with shuttle main engine test on the A-1 stand thrust directed downward, as during an was conducted Sept. 29, 2006. actual rocket launch. n A total of 35 tests of the XRS-2200 linear n Construction of the A-1 Test Stand aerospike rocket engine was conducted spanned a time period from December on the A-1 stand. These included the first 1964 to February 1967. powerpack test on Oct. 2, 1998, the first full-engine test on Oct. 7, 1999 and the n A variety of articles have been tested final hot fire test on Aug. 6, 2001. on the A-1 Test Stand – Saturn S- II rocket stage, J-2 engine, space shuttle n Nine tests of the J-2X powerpack were main engine, aerospike engine, J-2X conducted on the A-1 Test Stand from engine and RS-25 engine. Dec. 18, 2007 to May 7, 2008. A second round of 13 powerpack test firings were n Seven tests on five Saturn S-II stages conducted Feb. 15, 2012 to Dec. 13, 2012. (each with five J-2 engines) were Five gimbal tests of the J-2X engine were conducted on the A-1 stand. The first was conducted on the stand from June 14, 2013 Sept. 19, 1967; the last was Nov. 14, 1969. to Sept. 5, 2013. n Gimbal testing involves rotating engines a few degrees n Cooling the flame deflector with water creates steam in all directions, just as must occur during an actual flight that is forced out of the stand to form a billowing cloud to ensure proper trajectory of a spacecraft. often mistaken for smoke. Depending on outside temperatures, the hot steam may condense after n The first test of an RS-25 rocket engine was conducted exiting the stand and create light raindrops. on the A-1 Test Stand on Jan. 9, 2015. On April 4, 2019, Stennis completed testing of all 16 RS-25 main engines n Propellants for rocket engine test are supplied by that will help launch the first four SLS missions and all a 40,000-gallon liquid oxygen run tank and a 110,000- new controllers to be used by these former space shuttle gallon liquid hydrogen run tank mounted on the A-1 main engines stand at Level 10. for the first four When fully loaded, missions. The the test stand tanks April 4 test ended can supply enough a 51-month test propellant to conduct series at Stennis a typical engine test that demonstrated of 350 seconds. RS-25 engines can perform at the n RS-25 engines higher power level are tested at needed for SLS. full-duration, which means they are n The A-1 Test Stand fired for the same extends 58 feet amount of time they below ground and must fire during an 158 feet above actual flight to lift a ground, with a total vehicle into space footprint of 7,498 A full-duration test feet. of more than eight minutes requires n The A-1 Test Stand more propellant can withstand than the stand’s run rocket engine tanks can supply. thrust up to about Thus, the run tanks 1.1 million pounds are resupplied of force; the thrust during an engine limit is known as test by a nearby the maximum propellant barge dynamic load. connected to the stand. n The Stennis High-Pressure n Propellants Industrial Water needed for rocket Plant delivers as engine tests are much as 170,000 stored on site gallons of water RS-25 developmental engine No. 0525 is readied for installation on the A-1 andthen delivered per minute at 225 Test Stand on July 23, 2018. at super cold pounds per square temperatures – inch to the A-1 Test Stand during a test. The water is as low as minus 280 degrees Fahrenheit for liquid used to cool the flame deflector and keep it undamaged oxygen and minus 420 degrees Fahrenheit for liquid as it redirects thrust exhaust, which exceeds 6,000 de- hydrogen. Test stand piping must be designed and grees Fahrenheit, out of the stand. structured to withstand such extreme temperatures without leaking or rupturing. n The flame deflector is made up of 21 stacked angular segments – or water boxes. Each segment is drilled n Excess liquid hydrogen that is not consumed by an with a pattern of holes to direct pressurized water as engine before, during and after a test is burned off needed to cool the stand’s flame deflector. through a nearby chimney stack.