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TO CREW OR NOT TO CREW?

February 21st, 2017

That is the question to which NASA’s Acting Administrator Robert Lightfoot is seeking an answer. Last week, Lightfoot directed that a feasibility study be conducted on whether the first “Exploration Mission” flight – EM-1 – could be a crewed mission rather than the uncrewed flight that is currently planned. In the media flurry that followed, there was a great deal of speculation about the reason for the requested study: whether or not a crewed first flight is a good idea, whether the decision to conduct a study meant that NASA was focusing on the Moon vs. Mars, and even a question or two about the topic was posed to Congressional witnesses who were testifying during a previously-planned hearing about the past, present and future of NASA’s programs.

Image credit: NASA
Image credit: NASA

Nearly lost in all of the hubbub was a clear understanding of what is meant by a “feasibility study.” The outcome of such studies is usually not a simple “yes” or “no” answer.  There are four major variables that such studies try to characterize: technical, cost (budget), schedule, and risk. The latter of these, risk, may take many forms; risks to schedule or budget, technical risks, or mission risks, to name a few. The relationships among these four variables as well as the findings specific to the individual variables will drive the outcome of the feasibility assessment.

EM-1 Mission Profile

Currently, EM-1 is planned as an integrated test flight of the Orion spacecraft and the Space Launch System outfitted with the Interim Cryogenic Propulsion Stage (ICPS) as an upper stage (later flights of SLS will use the Exploration Upper Stage, designed to propel humans into deep space). Following launch on SLS, Orion will deploy solar arrays and the ICPS will give the vehicle the push needed to leave Earth’s orbit and travel toward the moon. Orion will then separate from the ICPS, which will then deploy several cubesats to perform some experiments and technology demonstrations. Afterwards, Orion would be propelled on toward the moon by a service module provided by the European Space Agency.

Image credits: NASA/MSFC
Image credits: NASA/MSFC

 

This outbound trip to the moon will take several days, during which engineers on the Earth will receive telemetry from Orion enabling them to evaluate its systems and correct its trajectory if needed. Orion will skim about 60 miles above the surface of the moon, and then use the moon’s gravitational force to enter a new deep retrograde orbit (opposite the direction of the moon’s rotation) about 40,000 miles away form the moon. Orion will remain in that orbit for about 6 days to collect data and allow mission controllers on the earth to assess its performance.

To get back to Earth, Orion will do another close flyby to within about 60 miles of the moon’s surface, then rely on another gravity-assist from the moon together with a boost from the service module to accelerate back home – back to Earth.

The Feasibility Study

Technically, three major points that are sure to be included in the feasibility study will be (1) whether the Orion spacecraft can be outfitted with an environmental control system that is sufficiently robust to maintain human life for the duration of the mission in time to execute EM-1, (2) whether the Space Launch System can itself be “human rated,” and (3) whether the ground systems currently in development for EM-1 can support crewed missions.

What does it mean to “human rate” a system? Well, a human-rated system does four things according to NASA: (1) accommodates human needs, (2) utilizes human capabilities, (3) controls hazards and manages safety risks associated with human spaceflight, and (4) provides, to the maximum extent practical, the capability to safely recover the crew from hazardous situations. This statement makes up the basic three tenets of human rating: assuring the total system can safely conduct the mission, incorporating design features that accommodate human interaction with the system, and incorporating design features and capabilities to enable safe recovery of the crew from hazardous situations. NASA’s current configuration for EM-1 uses the ICPS upper stage for SLS. ICPS was not expected to support human spaceflight, so part of the feasibility study will involve what the technical “story” is when using the ICPS second stage in relation to the four requirements for a human-rated system listed above.

Returning to Orion, the version of the deep space spacecraft that is flying on EM-1 was not intended to take humans, so it too is not currently “human rated.” However, Orion has already flown on Exploration Flight Test-1 (EFT-1) in December of 2014. Several modifications to the spacecraft have been made as a result of the knowledge gained from that flight.  The additional modifications needed to fly humans are largely known; however, the vehicle currently in production for EM-1 was not intended to incorporate them (for information on environment control and other subsystems needed for deep space missions, take a look at this presentation from an event sponsored by the Coalition last year on deep space habitats). Orion, too, would have technical requirements that would need to be met in order to fly humans on EM-1.

Finally, the ground systems at Cape Canaveral have been developed along a timeline paralleling that of the EM-1 and EM-2 missions. Some analysis may need to be done to see if those systems will be able to support a crewed EM-1, and if not, to determine what additional work will be needed in order to do so.

What’s Next?

Technical analysis, modifications, and impacts to system integration needed to achieve human-rated systems for EM-1 are very unlikely to fit within the current schedule for the mission. In addition, the “forward work” needed to achieve crew participation in EM-1 is currently not budgeted for such an accelerated timeline. The risk to the mission and the crew that is associated with making such changes (under varying budget and schedule assumptions) will need to be assessed. Introducing such changes into a previously-defined plan presents some unique challenges. Finally, the mission profile itself could change.

The interaction of all of these variables–technical, schedule, budget and risk, and their impacts to the mission plan–will drive the outcome of the feasibility assessment. Robert Cabana, the Director of the Kennedy Space Center (KSC) said on February 17 that the goal is to complete the feasibility study by the end of March. Meanwhile, work goes on around the country, with businesses large and small building the SLS, the Orion crew vehicle, and supporting the updates to the ground systems at KSC. For more on what’s happening right now, check out this video, produced by Coalition members who are proudly supporting America’s deep space exploration program!

SLS vehicle assembly building. Image credit: NASA/Frank Michaux
SLS vehicle assembly building. Image credit: NASA/Frank Michaux

 

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