NASA’s skyscraper-size Space Launch System (SLS) rocket, the successor to the agency’s space shuttle program that ended four years ago and the first exploration class launch vehicle to be developed since the days of the Apollo moon program, has cleared all the steps to complete its Critical Design Review (CDR). This crucial milestone comes nearly a year after the first successful test flight of the Orion Multi-Purpose Crew Vehicle (MPCV), designated Exploration Flight Test 1 (EFT-1); the capsule, along with SLS, will be instrumental in taking astronauts back into deep space for the first time since 1972’s Apollo 17 lunar mission.
NASA divulged that the CDR examined the Block 1 configuration of the launch vehicle, which is billed as having a 70-metric-ton (77-ton) lift capacity; it will boast two segmented boosters manufactured by Orbital ATK and four Aerojet Rocketdyne RS-25 engines, the space shuttle’s workhorses. The SLS Program completed the review in July; in addition, a separate review was made by the Standing Review Board, comprised of NASA and industry experts familiar with the program.
NASA underscored the amount of data required to undertake the extensive review: “Throughout the course of 11 weeks, 13 teams – made up of senior engineers and aerospace experts across the agency and industry – reviewed more than 1,000 SLS documents and more than 150 GB of data as part of the comprehensive assessment process at NASA’s Marshall Space Flight Center in Huntsville, Alabama, where SLS is managed for the agency.”
The Standing Review Board confirmed that SLS’s technical milestones are “on track to complete system development and meet performance requirements on budget and on schedule.” The agency’s Program Management Council, led by Associate Administrator Robert Lightfoot, was briefed concerning the CDR this month. The review for individual elements including the core tank stage, twin boosters, and engines was completed successfully.
SLS Program Manager John Honeycutt emphasized the importance of this CDR by stating: “This is a major step in the design and readiness of SLS. Our team has worked extremely hard, and we are moving forward with building this rocket. We are qualifying hardware, building structural test articles, and making real progress.” A short NASA video released today further underscores the vital nature of the CDR, as the program is now “cutting metal” and producing flight hardware for every element. Following a 2017 design certification, a flight readiness review will take place before 2018’s Exploration Mission 1 (EM1), a shakedown flight that will test the integrated systems of the Block 1 launch vehicle, the European Space Agency (ESA)-built Service Module, and an Orion MPCV. This mission will see Orion making a circumlunar flight, the first of its kind utilizing a human-rated spacecraft since Apollo.
Video Credit: NASA’s Marshall Center on YouTube
The completion of the CDR comes during a year of milestones reached for SLS. Its solid rocket booster was test fired seven months ago, NASA’s Pegasus transport barge is being made larger to support moving the colossal rocket, acoustic sound-suppression testing is occurring, F-18 Hornet fighter jets are carrying out flight tests for SLS flight software development, test stands are being built or modified, Kennedy Space Center’s (KSC) iconic Vehicle Assembly Building (VAB) is being upgraded to support SLS, launch pad 39B is being prepared, the rocket’s Mobile Launch Platform (MLP) and Crawler Transporter are being prepared, and both qualification and flight hardware for the first SLS vehicle itself are being constructed for the inaugural 2018 launch on the EM-1 flight with NASA’s Orion deep-space MPCV, which itself conducted its first flight test last December.
Test outcomes concerning the twin segmented boosters and the RS-25 engines, too, have yielded success. In May, NASA and Orbital ATK released their findings from the Qualification Motor-1 (QM-1) test fire. It was revealed that the 154-foot-long booster, the largest of its kind in the world, performed well at the highest end of its accepted propellant temperature range; the test was regarded as a “resounding success.” Orbital ATK released a report stating: “Current data show the nozzle and insulation performed as expected, and ballistics performance parameters met allowable requirements. Additionally, the thrust vector control and avionics system provided the required command and control of the motor nozzle position.” A cold-temperature test, Qualification Motor-2 (QM-2), is expected to take place next spring. Following the completion of that milestone, Orbital ATK will be ready to proceed toward EM-1.
Meanwhile, the seventh test fire of an Aerojet Rocketdyne’s RS-25 engine, the same kind of engine that powered the space shuttles to Earth’s orbit from 1981 to 2011, went off without a hitch in August; the test was carried out by a development engine. More test fires of both flight and development engines will take place at NASA’s Stennis Space Center in southern Mississippi throughout this fall. The engines have been modified for SLS and have new state-of-the-art controller units, characterized as “brains” that communicate with the launch vehicle.
One big change was revealed concerning SLS today: the launch vehicle’s paint scheme. NASA revealed that part of the CDR concluded that the 200-foot-tall core stage and Launch Vehicle Stage Adapter (LVSA) will not be painted white, but will remain orange. This compromise was made presumably to conserve weight; the first two space shuttle missions in 1981 utilized external tanks painted white, but soon the paint was nixed to conserve approximately 600 pounds of weight. A NASA report last month stated that a test version of the LVSA is being fabricated; this component is vital in connecting SLS’s core stage and upper stage.
NASA continued that integrated spacecraft and payloads are nearing their CDR completion, while other future program reviews will focus on SLS integration and flight readiness. The first human-helmed flight of SLS is to take place no later than 2023, with targets such as asteroids and Mars, our closest planetary neighbor, in our sights.
AmericaSpace’s Editor Mike Killian contributed to this story.
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