In less than two years’ time, NASA intends to loft its first unmanned Orion spacecraft on the long-awaited Exploration Flight Test (EFT)-1 mission atop United Launch Alliance’s gigantic Delta IV Heavy booster. The mission, which will rise to a maximum altitude of 3,600 miles—the highest a human-capable vehicle has flown since the end of the Apollo era—will serve to wring out many of Orion’s systems in readiness for its first Exploration Mission in late 2017. NASA took one step toward the EFT-1 goal yesterday (Thursday), by completing the latest in a series of parachute drop tests of a mock-up vehicle at the US Army’s Yuma Proving Ground in Arizona. The test confirmed that Orion could land safely even if one of its two parachutes failed to open during the critical final stages of descent.
“The mock-up vehicle landed safely in the desert and everything went as planned,” said Chris Johnson, one of NASA’s project managers for the Orion parachute assembly system. “We designed the parachute system so nothing will go wrong, but plan and test as though something will so we can make sure Orion is the safest vehicle ever to take humans to space.” Although the 21,000-pound Orion capsule will be fitted with a total of five parachutes—two 23-foot-wide drogues and three 116-foot-wide main canopies—it requires only a single drogue and only two mains to return safely. The others provide a backup capability in the event of a primary failure.
Yesterday’s test encompassed airdropping the Orion mock-up from 25,000 feet and running a simulated failure of one of the drogues. Approximately 30 seconds into the free-fall, the second drogue successfully opened and slowed the vehicle sufficiently for its three main chutes to control the remainder of the descent. But that is not all. When the next parachute test takes place in February, it will run through a simulated failure of one of Orion’s main canopies. And by the time that test takes place, EFT-1 will be a little more than 18 months away from actual realisation.
Tentatively set for September 2014, the unmanned mission has already moved more than a year to the right. It was originally scheduled for next July, but was postponed until December 2013, then the following spring, and now seems to have stabilized with a spot in the third quarter of 2014. Although no specific reasons have been given to explain the slippage, it seems likely that spreading program costs over a longer term were a key factor in the joint decision between NASA and Orion’s prime contractor, Lockheed Martin.
The spacecraft arrived at the Kennedy Space Center’s Operations and Checkout Building from the Michoud Assembly Facility in New Orleans, La. last July, and engineers are presently stepping through a 17-month process to ready it for flight. The EFT-1 mission will begin from Space Launch Complex (SLC)-37 at Cape Canaveral Air Force Station and is expected to consist of a two-orbit test of the Orion crew capsule—powered on this occasion by internal batteries, rather than photovoltaic arrays—with an apogee of 3,600 miles on the second orbit. This will produce a lunar-return re-entry velocity in excess of 20,000 mph to wring out Orion’s heat shield, avionics, and the performance of its parachutes.
This velocity is several thousand miles per hour faster than any human-capable vehicle in the last four decades, and Orion will descend from a peak orbit 15 times higher than the International Space Station. Such high altitude and energy will run its complex heat shield—comprising a thermal protection material known as an Avcoat and Phenolic Impregnated Carbon Ablator on the base of the spacecraft and several hundred tiles, bonded to composite laminate face-sheets on a titanium honeycomb core, on its main backshell.
Although the first Exploration Mission of Orion atop the mammoth Space Launch System (SLS) rocket—presently baselined as an unmanned circumlunar jaunt in December 2017—remains half a decade into the future, the success of EFT-1 is expected to provide significant data to support its more ambitious later voyages. According to NASA’s EFT-1 Fact Sheet, the inaugural mission will enable engineers to better understand the functionality of systems whilst on the launch pad, including fuelling and vehicle stacking, together with the retrieval of the crew module from the Pacific Ocean after splashdown. Moreover, the effort to build the EFT-1 Orion has enabled the space agency to “refine its production and co-ordination processes” as part of what is almost universally acknowledged to be “the world’s most cutting-edge spacecraft”.