NASA discusses SLS and Orion progress at ‘Day of Mars’ event
NEW ORLEANS — Before wowing onlookers with the sights and sounds related to testing an RS-25 engine, NASA sought to educate members of traditional and social media outlets about agency and industry efforts related to the Journey to Mars.
However, before the agency can begin sending ships and crew beyond Earth’s neighborhood, they must first complete the rocket and spacecraft that will enable that journey. A televised panel discussion with NASA personnel started the day with a status update of the Space Launch System (SLS), accompanied by a discussion of the challenges the agency must consider in reaching the Red Planet with a crewed mission and the efforts underway to overcome them.
Bill Hill, NASA’s deputy associate administrator for Exploration Systems Development, outlined the progress the agency is making with SLS.
Exploration Mission 1 (EM-1), the maiden launch of the SLS, is still on-track for a late 2018 liftoff and will send the Orion spacecraft on a distant retrograde orbit around the Moon. It will be the only mission to use the Interim Cryogenic Propulsion Stage (ICPS). The pressure vessel for that Orion craft has already been delivered to Kennedy Space Center (KSC) in Florida.
“I would have preferred for [the mission] to have been called EFT-2,” Hill said, in an apparent nod to the experimental nature of Orion’s previous mission on Exploration Flight Test 1 (EFT-1).
Notably, though not related, Hill also mentioned it is NASA’s ultimate goal to turn over the International Space Station to commercial entities at the end of the agency’s commitment in the mid-2020s.
Lara Kearney was also on-hand to explain some of the changes in the Orion spacecraft following its maiden flight in December 2014 atop a Delta IV Heavy.
Kearney, NASA’s Orion Crew and Service Modules manager, noted the spacecraft has evolved from 31 separate structural pieces for the EFT-1 mission to seven for the EM-1 flight. Not only has the number of structural components been significantly reduced, but nearly 1,000 pounds (453 kilograms) of mass has been removed from the spacecraft.
Prior to visiting the Vertical Assembly Center, where the world’s largest spacecraft welding tool is nearing completion of the flight article for the mammoth liquid hydrogen tank for the SLS core stage, SLS Stages Element Manager Steve Doering allowed for a small detour to see the completed structural test article for the tank.
Currently undergoing installation of sensors, the 130+ feet (∼40 meters) long tank will eventually be shipped to NASA’s Marshall Space Flight Center (MSFC) in Huntsville, AL, where it will be subjected to simulated flight loads in a recently-constructed test stand so that the design can be validated.
Beyond simply discussing the progress of SLS and Orion toward EM-1, NASA also provided access to propulsion experts.
To date, all human-rated spacecraft have relied on chemical propulsion, whether it be solid fuel, cryogenic, semi-cryogenic, or hypergolic. However, there is a theoretical limit to the efficiency one can expect out of those more traditional methods: approximately 450 seconds of specific impulse (Isp). Isp measures the change in momentum delivered per unit of propellant consumed by the engine. One can roughly equate this to the fuel economy rating of an automobile.
Due to the inherently more efficient nature of a nuclear thermal rocket engine – originally tested more than fifty years ago as part of the NERVA (Nuclear Engine for Rocket Vehicle Application) program – there is renewed interest in the practical use of the technology for deep space missions. The NERVA tests showed an efficiency level of 850 seconds Isp – nearly twice that of the RS-25.
Tony Kim, project manager for nuclear propulsion at NASA’s Marshall Space Flight Center, is in the early conceptual design phase for a restart of the program and is confident that efficiencies can be increased to 1,000 seconds Isp.
Kim, an emphatic supporter of nuclear thermal engines, posits that such an engine would be safe to launch and would be much safer for astronauts as it would reduce total flight time on a Mars mission by 3 to 4 months, directly reducing the amount of time the crew would be exposed to potentially harmful radiation, both from the sun and from interstellar sources. Such an engine would only use 5.5 pounds (2.5 kilograms) of low-enriched uranium on a round-trip mission to the Red Planet, in addition to its liquid hydrogen propellant.
Though nominally a topic of public derision, Kim asserts now is the time to resume work on a nuclear thermal engine and he feels the public is ready.
“We understand nuclear power,” Kim said when asked about his rationale.
Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.