Dual SLS launch campaign required for NASA’s Lunar return
A return to the surface of the Moon would require two Space Launch System (SLS) rockets launching over half a year apart, with a four person crew being transported to the Lunar surface on a multi-billion dollar Lander for a seven day sortie mission. The overview, provided in the latest Concept Of Operations (CONOPS) document, all-but rules out the option based on cost estimates alone.
Apollo On Unaffordable Steroids:
Often cited as the preferred opening exploration option by numerous lawmakers, a return to the surface of the Moon would realign NASA with the plan outlined in the Vision for Space Exploration (VSE), before the aborted Constellation Program (CxP) failed to deliver on its goals.
CxP utilized a 1.5 launch architecture with its Ares I Crew Launch Vehicle (CLV) tasked with launching astronauts on the Orion spacecraft, in tandem with the Ares V Cargo Launch Vehicle (CaLV) that would provide the heavy lift for the Altair Lunar Lander.
Classed as “Apollo on Steroids”, Ares I and Orion would have first provided crew rotations of NASA astronauts on the International Space Station (ISS), prior to an upgraded Orion being re-tasked to conduct into Beyond Earth Orbit (BEO) for sorties to the Lunar Surface by the year 2020, all of which would provide the experience for venturing out towards Mars.
The “Moon, Mars and Beyond” plan was ambitious, with a 2006 Mission Manifest (acquired by L2) showing a return to Lunar Missions had been scheduled for June, 2019 – involving the second flight of the Ares V and the twelfth mission for Orion.
Classed as a full dress rehearsal, all mission objectives – bar landing – would have taken place, ahead of the first full-up mission in December of that year.
Cited as “Surface Recon and Exploration” – Orion 13 would have been quickly followed by the next Moon landing in June, 2020.
With technical issues and budget shortfalls, this manifest soon started to slip, leading to the Augustine Commission review of NASA’s Human Space Flight objectives, a meeting that provided one of the final nails in the Constellation Program’s coffin.
With the Agency realigned to the FY2011 plan from President Obama’s administration, Orion – NASA’s only planned replacement for then-retiring Space Shuttle – was cancelled as part of the CxP cull.
Amid wide-scale discontent with the new plan, Orion was brought back from the dead, but only in the role of a lifeboat on the ISS.
It took the 2012 Authorization Act to fully realign the FY2011 proposal into a plan that involved Orion being used as a BEO vehicle, launched by the Space Launch System (SLS).
With NASA managers conducting additional reviews and exploration planning it was decided the opening missions would concentrate on the Moon, albeit without landing on the lunar surface.
Known as Exploration Mission -1 (EM-1) and Exploration Mission -2 (EM-2), the Block 1 SLS was to loft Orion on an uncrewed flight around the Moon, prior to a crewed version a full four years later.
The large gap related to political instructions to ready SLS and Orion for a 2017 role in backing up ISS crew rotations, in the event Commercial Crew providers failed to come on line in time.
NASA managers then changed EM-2 into a crewed flight to a captured asteroid, with a Change Request currently being evaluated to refine EM-1 to an uncrewed mission that will send Orion thousands of miles past the Moon – a move that is designed to aid operational understanding ahead of EM-2.
Since NASA announced the asteroid mission plan for EM-2, a number of lawmakers have been less than enthusiastic, claiming they would prefer the Agency concentrated on returning to the surface of the Moon instead.
Almost immediately, NASA Administrator Charlie Bolden countered such proposals via strongly worded comments at May’s Explore Mars conference.
“We need to try and get all of us on to the same sheet of music in terms of the roadmap,” noted the NASA head. “(If we) have someone in the next administration who could take us back to a human lunar mission, it’s all over, we will go back to square one.”
General Bolden’s comments focused mainly on the costs associated with a Lunar return, not least when NASA’s funding is completely insufficient for the additional hardware – such as the Lunar Lander – required for returning to the surface.
However, internal documentation had already placed the potential for NASA missions to the Moon’s surface within the ESD Concept Of Operations (Con Ops) presentations (L2) – listing it alongside the main NEA (Earth Earth Asteroid) missions under the Architectural Timeframe Design Reference Missions (DRMs).
Moreover, the latest Con Ops presentation – an expansive document covering EM-1 through to Mars – provided the most extensive overview of the Lunar Sortie DRM, as much as it adds to the rationale behind General Bolden’s cost concerns.
Unlike the days of Apollo, where one Saturn V was capable of launching the Apollo spacecraft, the crew, the lander and ascent module with associated hardware, a return to the Moon with SLS and Orion would require the use of two SLS 105mT Block 1A/B launch vehicles.
“The Lunar Surface Sortie DRM lands four crew members on the surface of the Moon in the equatorial or polar regions and returns them to Earth,” noted the outline in the latest Con Ops presentation, available to download in L2.
“The equatorial and polar regions are chosen to reduce the lunar delta-v requirements compared to mid-latitude regions. For surface stays of approximately seven days, this DRM is accomplished with a series of two 105-t SLS launches.”
Currently, SLS can only launch once every six months, with the outline taking this into account by staging the Lunar Sortie mission into two parts, in addition to changing the Apollo approach by opting for a Lunar Orbit Rendezvous (LOR) of the hardware.
“SLS-1 puts the Lunar Lander with a Block 1 Cryogenic Propulsion Stage (CPS-1) into LEO while SLS-2 puts the Orion with another Block 1 CPS (CPS-2) into LEO,” added the overview.
“Instead of docking the Orion with the Lander in LEO, this DRM uses a dual Lunar Orbit Rendezvous (LOR) mission design that performs Rendezvous, Proximity Operations, Docking, and Undocking (RPODU) sequences in LLO (Low Lunar Orbit). CPS1- transports the Lander to LLO and CPS-2 transports the crewed Orion.
“Due to the spacing between SLS launches, the Lander is required to loiter for a long period in LLO. The Orion, as the active vehicle, docks to the waiting Lunar Lander. The Orion remains primary for all elements until the crew members transfer into the Lunar Lander.”
Following rendezvous and docking of the Orion and Lander in LLO, the crew would then transfer into the Lunar Lander and descends to the Moon’s surface.
The Lunar Lander would be designed to provide habitation for seven days duration on the surface, while Block 2 EVA Deep Space Suits would be required for surface EVA operations.
Although the use of two SLS vehicles would be very costly, the superior upmass ability would allow for an ambitious lander, as depicted in the Con Ops presentation.
“The Lunar Lander provides transportation for crew members to and from the Lunar surface and supports crew members for short duration lunar surface stays. The Sortie Lunar Lander two-module configuration consists of the Descent Module (DM) and the Ascent Module (AM). The AM includes Suit Ports and a side hatch opening to the Lunar Lander deck. All crew equipment, supplies, and consumables are stowed in the AM.
“The Lunar Lander also has a three-module vehicle configuration for extended stays consisting of the DM, the AM, and a Suit Lock/Suit Port (SL) module. The Suit Ports minimize the time required for the crew members to don suits and begin surface EVA, and minimize atmosphere losses.”
Notably, even a version of Constellation’s Altair Lander is classed as one of the major reasons for General Bolden’s dismissal of such missions being viable, with the cost of a lander in the several billion dollar range.
Per the overview provided by the Con Ops document, the final leg of the mission would closely match that seen during the Apollo days.
“Once surface operations are complete, the Lunar Lander’s AM returns the crew members to LLO and docks with the Orion. The Orion has enough delta-v capability to support plane changes required to meet up with the Lander AM for any time ascent. Some loiter time in LLO may be required in this situation to wait for a window to return to Earth. The AM is disposed of before the Orion departs for Earth.”
Although – as mentioned – such a mission is not going to occur unless lawmakers provide NASA with the additional funding, a large amount of work has clearly taken place from within the Exploration Systems community, with the presentation adding expansive timelines for the entire mission.
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However, until such lawmakers support a Lunar return with additional funding, General Bolden’s concerns are likely to remain in pole position for NASA’s forward path, adding “I believe (that would mean we) would have missed the second greatest opportunity for humanity to go on to deep space and do what humans have wanted to do for hundreds of years (if we are tasked with returning to the Lunar surface).”
(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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