Orion may require 30 hour orbital checkout prior to TLI
NASA teams are exploring the possibility of launching Orion into a High Elliptical Orbit (HEO), where the spacecraft will remain “parked” for 30 hours. The move – that would be implemented during Exploration Mission -2 (EM-2) – would allow for a checkout of the spacecraft’s life support systems, prior to then conducting the Trans Lunar Injection (TLI) burn.
Orion’s debut trip into space is just one year away, with a launch atop of a Delta IV-Heavy set to loft the new spacecraft on the Exploration Flight Test -1 (EFT-1) mission, designed to evaluate the performance of the heat shield during a high velocity re-entry.
With the results of what are numerous mission objectives then feeding into Orion’s Critical Design Review (CDR), the spacecraft would then move into preparations for life with its new partner in crime, the Space Launch System (SLS).
The debut of SLS and Orion remains on track for December, 2017 – with a 25 day uncrewed flight on the books, resulting in the spacecraft being sent to a destination 70,000 km past the Moon, prior to re-entry and splashdown in the Pacific Ocean.
While this mission is currently being debated via a Change Request (CR), its original mission to conduct an orbital laps close to the to the lunar surface is no longer required, after NASA administrator Charlie Bolden strongly ruled out any return to the surface of the Moon, placing the emphasis on asteroid missions.
The realigned Exploration Mission -1 (EM-1) will also serve as a dress rehearsal for the first crewed mission involving Orion and SLS, known as Exploration Mission -2 (EM-2).
EM-2 involves two distinct elements of what is known as the Asteroid Redirect Crewed Mission (ARCM).
First, a 2019 mission is to involve the launch of an Asteroid Retrieval Spacecraft (ARS) via an Atlas V in its 551 configuration, setting sail for an asteroid that would be “small enough” and relatively close by.
It would then capture the rock, before placing it in the vicinity of the Moon within one to two years.
Once the asteroid is in position, SLS would launch a crew of two astronauts on an Orion to meet up and conduct EVAs on the asteroid and take samples.
The focus on crew safety – for what will be the debut crewed mission for Orion – is a key area of evaluation for NASA managers.
An updated status for the safeguards that may be implemented on EM-2 were recently provided to a meeting with NASA’s Aerospace Safety Advisory Panel (ASAP).
The influential body were informed that NASA managers are considering holding Orion close to the planet for over a day, allowing for the checkout of life support systems and vehicle health, prior to a green light for the Trans Lunar Injection (TLI) burn that would finally send the crew on their way into deep space.
“EM-1, the uncrewed mission, is scheduled to fly in December 2017, and it is moving along. EM-2 will be the first crewed flight, currently scheduled for 2021,” noted minutes from the meeting at the Marshall Space Flight Center (MSFC).
“This (EM-2) is the mission that the ASAP had questions about – specifically, a first crewed flight with the first use of the ECLSS (Environmental Control and Life Support System) and other systems onboard, (plus the) concerns about how to mitigate risk.”
The NASA team present responded to the ASAP questions by noting the Program is addressing the risks, before describing several items on how they would ease crew safety concerns. One of the responses related to checkouts close to Earth before committing to deep space.
“There is one approach that includes a 30-hour high elliptical orbit (HEO) for checkout before committing to a trans-lunar return,” added the minutes. “The Program is still exploring this approach.”
Considerations include the potential for additional Micro Meteoroid Orbital Debris (MMOD) risk and radiation exposure from remaining in such an orbit.
However, due to the mission being both complex by nature and the first time humans will fly on Orion, the ASAP believe the 30-hour checkout proposal is a “more prudent” approach for the flight.
“Combining the first crewed-flight mission with an asteroid mission complicates the mission considerably, and a number of things would need to be resolved,” the minutes added. “The Program team is in the process of figuring out what will work.
“The ASAP was satisfied that there are activities directed at characterizing and mitigating the risks associated with the first crewed flight, EM-2, and that the first-flight risk would be potentially reduced through the 30-hour checkout proposal. This appears to be a more prudent way to go.”
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It is not yet known if this checkout procedure would be then implemented into following missions.
Currently, the SLS mission manifest remains in flux, with only the first two EM flights receiving Design Reference Mission (DRM) approval into the baselining procedure. However, L2 information points to what may be the first six missions for NASA’s new monster rocket.
The information includes launch slots for the Heavy Lift Launch Vehicle (HLV) in its “cargo-only” configuration, a potential mission to launch the first Deep Space Hab (DSH) into a long-duration Lunar orbit test flight profile, followed by an “initial capability” long-duration mission to a deep space asteroid in the early second half of the 2020s.
However, due to continuing budget uncertainties, long-term planning is always classed as notional, with the concentration focused on the opening two EM flights.
(Images: Via L2 content from L2′s SLS specific L2 section, which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site. Other images via NASA)
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