NASA’s massive heavy-lift rocket, the Space Launch System, which will one day ferry humans to deep-space destinations and back, has become notorious for the scale of engineering backing it. In September 2014, agency administrator Charles Bolden had unveiled the world’s largest welder to mark the start of the SLS’s construction. Next, on March 11, NASA will test history’s largest and most powerful booster that will power the SLS.
The booster has five stages, and has been adapted from the four-stage version used for the Space Shuttle program. It is 47 meters in length, 3.6 meters in diameter, and weighs 801 tons. The test-fire will be conducted by prime contractor Orbital ATK at its T-97 test stand in Promontory, Utah, at 11.30 am EDT (9 pm IST) on Wednesday.
Even though the booster’s components have been verified in the past, the addition of the extra stage makes it a new configuration that engineers must test for once more. Wednesday’s test, in this context, will be for the full duration – two minutes – for which it will be expected to fire on launch day, although it will be laid horizontally on a test-bed (like in the video below).
The maximum thrust it produces will be about 16 million newtons, burning 5,500 kg of solid propellant per second. On the SLS itself, two such boosters will join four RS-25 engines to generate a combined thrust of 37.3 million newtons. (To compare, an Airbus A380-800 uses four Rolls-Royce Trent engines to generate a combined thrust of 0.96 to 1.68 million newtons to fly.)
Here’s a video from 2009 showing how one of these tests goes (Don’t miss it when the commentator says, “Amazing display of power” at 1:36).
https://www.youtube.com/watch?v=J2UDTNEPr0Y
A second test will happen in March 2016. This month’s test will qualify the booster for operation at 32 degrees Celsius, the one next year will qualify it for performance at 4 degrees Celsius. The disparate temperatures mimic the two which the booster will be expected to perform in: during launch and in space. If both tests are successful, it will finally have to pass a design certification review in the last third of 2016 to finally qualify for use.
The idea for the SLS was born from NASA’s desire to cope with its Constellation Program starting to crumble in 2009, when President Barack Obama cancelled all deep-space exploration efforts. In efforts to ensure its $9-billion investment remained fruitful, the agency conceived of the SLS, with a new rocket at its heart. A lot of hope also underscores this new commitment: plans for a booster-test date back to 2012, while engineers conducted three test-firings of the booster between 2009 and 2011 during development for the Constellation Program’s Ares rocket.
The multipurpose module on-board the rocket which will hold humans is called Orion, which the rocket has been designed around. The first test flight when both Orion and SLS will fly together has been planned for November 2018, when they will undertake a three-week long trip through an orbit just beyond the moon and return to Earth. Orion’s own inaugural (unmanned) mission was successfully completed in December 2014, with a Delta IV heavy rocket.
NASA plans for the SLS-Orion to be able to get humans to Mars in the 2030s. To get farther – such as to the asteroids between Mars and Jupiter – the agency plans to gradually step up booster capabilities. The 2018 test will lift 70 tons, with a rocket 64.6 meters tall and 8.4 meters wide.
Current projections place the ultimate goal at a lift capability of 130 tons into low-Earth orbit – the heaviest ever. The corresponding rocket will feature two five-stage boosters, four RS-25 engines and two J-2X engines, more closely resembling the giant Saturn V of the 1960s and 1970s, which was 110 meters high.
The booster’s prime contractor, Orbital ATK, was formed by the merger of Orbital Sciences and erstwhile prime contractor ATK (Alliant Techsystems) on February 9 this year. Orbital itself hit a rough patch in October 2014 when its flagship Antares rocket exploded seconds after taking off from a launchpad in Virginia. It was carrying supplies for a resupply mission to the International Space Station. Wednesday’s test-fire will be Orbital ATK’s first ‘mission’ as a merged company.
Both Orbital ATK and Boeing – the contractor for the SLS’s core module which carry cryogenic liquid hydrogen and liquid oxygen – have reused many features and parts from the erstwhile Space Shuttle program, helping cut costs. Ironically, however, the SLS boosters which contain parts from 23 different Space Shuttle missions across 25 years are not reusable.
NASA will broadcast the test live on its television channel, NASA TV. The event is sure to revitalize public support for an agency that seems long past its golden days, yet whose heritage and legacy are important for the USA to recapture its former foothold in space exploration.
At the same time, whether even a successful test-fire will bode well in the eyes of Congressmen is hard to say: the first SLS test-flight was originally planned for 2017, and now it’s 2018. The size of the program also makes it especially susceptible to changing political winds, as a result of requiring constant and substantial funding to be kept alive.
Making matters worse is, despite motoring along with the development of the SLS itself, NASA hasn’t yet said where it will actually go besides Mars.
Featured image: Artist concept of NASA’s Space Launch System (SLS) 70-metric-ton configuration launching to space. Credit: NASA/MSFC
