It seems as if we’re galloping toward the end of 2016, and we’re getting closer by the day to the “dawn” of a new U.S. launch vehicle and human-rated spacecraft. In a little over two years, NASA’s next “giant leap”—Exploration Mission 1 (EM1)—is aimed for a launch from Kennedy Space Center’s (KSC) Pad 39B. While two years may seem like a long time, much must take place before the Space Launch System (SLS) launch vehicle and its Orion crew capsule (integrated with a European Space Agency-built service module) are ready to leave Earth’s orbit for a flight 40,000 miles beyond the Moon and back.
On the SLS front, NASA continues to prepare KSC’s Vehicle Assembly Building (VAB) for the next-generation launch vehicle, while the massive core stage comes together at the space agency’s Michoud Assembly Facility in New Orleans, La. Meanwhile, the Orion crew capsule to be used for EM-1 received its essential heat shield. NASA is also preparing to test the ESA-built service module, and recovery processes after splashdown are also being practiced at Houston’s Johnson Space Center.
VAB Receives Modifications for SLS, While Core Stage Comes Together at Michoud
KSC’s iconic Vehicle Assembly Building (VAB), which was built during the mid-1960s for Apollo lunar missions, also supported the Skylab and shuttle programs. As we approach the 2020s, it now is en route to supporting SLS/Orion. NASA announced that the second half of the “D” level work platforms (D north) for the SLS launch vehicle were installed by a heavy-lift crane inside High Bay 3 of the VAB on Sept. 9. These platforms are the seventh of 10 levels of work platforms meant to provide machinery and workers with access to the heavy-lift rocket prior to EM-1. NASA stated that these modifications have been overseen by the Ground Systems Development and Operations Program. The SLS modifications to the VAB are now well over halfway complete.
It was also announced that welding was completed on the 130-foot-tall liquid hydrogen tank that will be utilized for EM-1 in late 2018. At present time, the rocket’s 212-foot-tall core stage is meticulously being put together by engineers at NASA’s Michoud Assembly Facility. NASA stated that at the facility’s Vertical Assembly Center, many of the core stage’s elements are being welded. In addition to the large hydrogen tank, the forward skirt, liquid oxygen tank, and engine section are also being welded at Michoud; another component, the intertank, is being fabricated there as well. The Boeing Company is the core stage’s prime contractor.
The SLS’s mammoth core stage will carry 2.3 million pounds of liquid hydrogen and liquid oxygen, which will in turn fuel four RS-25 engines, the same type of engine that powered the space shuttles reliably for 30 years. Together, this combination makes for a lot of power, and a lot of stresses.
To make sure they can take the pressure, the “wet” fuel-bearing sections of the rocket will undergo rigorous tests (such as hydrostatic and pneumatic testing) to be proven flight ready. “Dry” structures (such as avionics, cameras, computers, and assorted electronics) will be added, along with all-important orange-colored insulation so the rocket can withstand the extreme cold of liquid fuel temperatures, and the intense heat of launch. Joan Funk, SLS core stage lead at NASA’s Marshall Space Flight Center in Huntsville, Ala., likened the process to “building a house.” She related, “With the massive, welded elements coming off the Vertical Assembly Center at Michoud, we’ve laid the foundation, framed the walls and put up the roof. The big items are in place. Now it’s time to get to work on the inside.”
Following work at Michoud, the core stage will travel by barge to NASA’s Stennis Space Center in Mississippi for further testing and a hot fire test called a “green run,” in which the rocket’s engines are fired at nearly full power attached to the core stage. Once these milestones are completed, the core stage will head to KSC’s newly-modified VAB for its maiden voyage. The next destination? Into space.
Orion Update: Heat Shield, ESA’s Service Module, and Recovery Tests
While SLS continues to take shape, the Orion crew capsule to be used for EM-1 received a special delivery in August: its essential heat shield, which was transported via NASA’s Super Guppy aircraft to KSC’s Shuttle Landing Facility (SLF). Following its arrival, the still-boxed shield was taken to the Neil Armstrong Operations and Checkout (O&C) Building at the space center, where it was uncrated and placed on a stand. The 16.4-foot-wide heat shield was built by Lockheed Martin, Orion’s prime contractor, and the NASA Orion team at the company’s facility in Denver, Colo.
NASA stated that the heat shield for EM-1 will have some differences from the one flown on EFT-1, Orion’s first test flight, which took place in December 2014 aboard a United Launch Alliance Delta IV Heavy launch vehicle. The space agency emphasized that this time around, blocks of Avcoat (an ablative thermal substance) will be bonded to the shield; during EFT-1, the substance was filled into honeycomb cell structures. Of course, instrumentation will be attached to the spacecraft to give engineers an idea of how the heat shield responds to a high-energy reentry coming back from a deep space destination.
NASA also stated that in spring 2017, propulsion qualification testing for Orion’s European Service Module will take place at its White Sands Test Facility in Las Cruces, N.M. According to the space agency, the propulsion qualification module to be tested contains “flight-like test units of the engine, propellant systems, and propulsion control units.” The module is currently being built by ESA’s contractor, Airbus Defence and Space.
Another important facet of the Orion program involves recovery. For the first time since the mid-1970s, humans will splashdown under parachutes in the ocean following space missions. This is a far cry from the shuttle days, when crews could merely walk down a flight of stairs following a spaceflight. To be prepared, NASA is already practicing at-sea recovery operations. On Wednesday, Sept. 21, a group of U.S. Navy divers, Coast Guard rescue swimmers, and U.S. Air Force pararescuemen utilized an Orion capsule mockup for practice purposes at Johnson Space Center’s Neutral Buoyancy Laboratory in Houston.
While the VAB modifications and the SLS core stage continue to come together, the Orion crew capsule also is meeting vital milestones in order to make its next journey. EM-1, currently scheduled to launch in October 2018, will see the Orion crew capsule integrated with its European Service Module making a flight aboard a Block I SLS launch vehicle. Its next journey will take it well beyond the Moon and back, exposing the spacecraft and heat shield to high forces and temperatures (of up to approximately 5,000 degrees Fahrenheit). This mission will be another crucial stepping stone as NASA prepares to send humans further into deep space than ever before, to destinations such as Mars, our closest planetary neighbor.
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