Space

NASA’s Colossal SLS Rocket on Track for 2018 Test, with Tiny Hitchhikers

One of the largest rockets ever built will have its first unmanned test flight in 2018, its maker NASA announced on February 2. And onboard will be two sets of payloads crucial to planning the space agency’s manned deep-space missions of the future.

The giant Space Launch System (SLS) to be launched in 2018 is a version being called Block I. It will measure about 98 metres tall, slightly smaller than the Saturn V rocket that carried humans to the Moon. The SLS will also have 20% more thrust than the Saturn V and will be able to lift “more than any existing launch vehicle” – 70 tons during the test flight. A bigger variant will be the biggest of all-time, standing at 117 metres and capable of lifting 130 tons to the low-Earth orbit (to compare, India’s GSLV Mk-III stands at 44 metres and lifts 8 tons to the LEO). NASA hopes to use it to ferry humans to Mars in the 2030s, and even toward the Jovian and Saturnian systems after.

An artist rendering of the various configurations of NASA's Space Launch System (SLS). The flexible configuration, sharing the same basic core-stage, allows for different crew and cargo flights as needed, promoting efficiency, time and cost savings. Caption & credit: nasamarshall/Flickr, CC BY-NC 2.0

An artist’s rendering of the various configurations of NASA’s Space Launch System (SLS). The flexible configuration, sharing the same basic core-stage, allows for different crew and cargo flights as needed, promoting efficiency, time and cost savings. Caption & credit: nasamarshall/Flickr, CC BY-NC 2.0

The first test flight was supposed to happen in 2017 but was pushed by a year following budget cuts. NASA has said the 2018 flight will happen at a cost of $7.021 billion. If successful, it will be an important symbolic checkpoint as well. NASA retired its Space Shuttle fleet in 2011 after three decades of service and has since not had a launch vehicle of its own to carry humans into space.

The SLS will be powered by four Aerojet Rocketdyne RS-25 engines, which the Space Shuttles also used, and two boosters (also the largest ever built)*. The latter’s performance has to be tested at 32º C and 4º C (to mimic conditions on the day of the launch and in space, where they’ll be active). The 32º C test was performed on March 11, 2015, and the 4º C is slated to happen in the spring of 2016. A final certification review at the end of the year will qualify them for use. The four engines and two boosters will altogether generate as much thrust as 22 Airbus A380-800 airplanes (each of which uses four Rolls-Royce Trent engines).

A test-fire of the Ares 1’s five-segment solid rocket motor. The Ares program started to wind down in 2009 after Congress cancelled funding for it. The SLS was built to replace it.

The rocket’s primary payload will be the Orion spacecraft, the crew capsule to carry humans in the eventual manned missions. When the SLS enters Earth orbit, the Interim Cryogenic Propulsion Stage (ICPS) – at the helm of which Orion sits – will break away toward the Moon. As it gets closer to the Moon, Orion will then cut loose from the ICPS and carry on, propelled by a service module provided by the European Space Agency. Once the capsule is a safe distance away, the ICPS will deploy the secondary payload.

Orion will enter into a retrograde orbit around the Moon, at one point of which it will be 70,000 km from the body – no crew capsule in history will have flown that far from Earth. It will stay in the orbit for three weeks. As a result, according to a press statement, it “will stay in space longer than any ship for astronauts has done without docking to a space station and return home faster and hotter than ever before.”

On December 5, 2014, NASA had latched Orion onto a Delta IV Heavy rocket, which orbited Earth twice and then dropped the capsule into the atmosphere. Then, Orion’s guidance, navigation and propulsion systems had performed well but the heat-shield wasn’t up to the mark. Moreover, the capsule was landing upside down half the time during other tests. Whether the fixes for these issues are successful in 2018 will also be something to watch out for.

The secondary payload will be 13 shoebox-sized satellites called cubesats. Seven of them have been identified. Three will be decided in 2017, at the end of an international contest called the Cube Quest Challenge. These three cubesats will continue to compete for prizes in space as they complete various research tasks. Any nongovernmental group is allowed to participate in it. Another three will be from NASA’s “international partners” and their details will be announced later.

Of the seven, four will study the Moon and one will study particles and electromagnetic fields in space. A sixth cubesat, called BioSentinel, will carry yeast and observe how its biology is affected by radiation in space. This information will help engineers and scientists at NASA design suitable radiation shields to protect astronauts. The seventh, Near-Earth Asteroid (NEA) Scout, will unfurl an 86-squared-metre solar sail and use sunlight to propel itself the way sailboats do on Earth. It will slowly fly past the asteroid 1991VG and take pictures, transmitting them to ground stations.

“All systems go!” for 2018 is good news because it means NASA is on track and no substantial budget overruns are expected. Beyond a manned Mars mission, the agency hasn’t specified where exactly SLS will take humans and that’s not helping it secure appropriate funding. But for now, it will be a spectacle enough to see the giant get off the ground.

(Images: click to enlarge.)

Featured image: NASA’s Space Launch System rocket will launch with Orion atop it from Launch Complex 39B at NASA’s modernised spaceport at Kennedy Space Center in Florida. Caption & credit: NASA.

*The biggest version of the SLS will use four RS-25 engines, two J-2X engines and two boosters.