Space Sunday: Moon, Mars, and abort systems

Lockheed Martin: trying to assist NASA in putting humans back on the Moon in 2024. Credit: Lockheed Martin

On Tuesday, March 26th, Vice President Mike Pence directed NASA to accelerate plans to send humans back to the Moon, moving the planned first landing from 2028 to 2024. That presents an incredibly short time frame for the US space agency, given all that needs to be done.

Rather than going to the Moon directly – as with Apollo in the 1960 through 1972  – NASA’s plans for a return to the Moon require the establishment of an orbital facility around the Moon – the Lunar Orbital Platform-Gateway – plus the development of the vehicle to get to and from it (the Orion MPCV), and a vehicle to get from it to the surface of the Moon and back. This, coupled with trying to develop a completely new and complex launch vehicle – the Space Launch System – capable of putting all this hardware where it needs to be, means NASA has a huge mountain to climb to achieve their goal and maintain things like operating the International Space Station – and will need a lot of funding to achieve it, something which doesn’t as yet seem to be forthcoming.

The Lunar Orbital Platform-Gateway is a complex idea, potentially equalling the ISS in requirements – and development / construction time frame, making it improbable that it would be ready in full for 2024 lunar landing. Credit: NASA

As it is, the SLS, as recently noted in these pages, has yet to fly, and has seen a number of programmatic changes in order to try to meet a time frame that was already tight before Pence give his March directive. Following the announcement of the shift to a 2024 landing, NASA actually wavered over using it, mulling the idea of using a commercial launch system instead (the Delta IV Heavy is capable of launching the Orion, for example) before deciding they would push to use SLS. However, in doing to, the agency then suggested they could cut the “green run” test of the SLS first stage, potentially shaving 6 months from the development / flight schedule for the first launch.

Viewed as a crucial pre-flight test, the “green run” would see the completed first stage shipped from the Michoud Assembly Facility, Louisiana, to the Stennis Space Centre, Mississippi, where its four RS-25 engines would be fired for eight minutes, simulating the actual flight of the vehicle prior to upper stage separation. It has been regarded as a crucial test, intended expose the untried first stage to the full force of a simulated launch to gather vital data on the stage performance and to see how the entire assembly stands up the rigours of launch and what might need to be re-worked, etc. The suggestion was that NASA skip it in favour of individual tests of the four RS-25 motors – potentially shaving 6 months off the SLS development schedule.

But on April 25th, the Aerospace Safety Advisory Panel (ASAP) met to discuss this idea and strongly advised NASA not to avoid the “green run”.

There is no other test approach that will gather the critical full-scale integrated propulsion system operational data required to ensure safe operations. Shorter-duration engine firings at the launch pad will not achieve an understanding of the operational margins, and could result in severe consequences. I cannot emphasize more strongly that we advise NASA to retain this test … as NASA evaluates different paths to potentially accelerate the EM-1 flight, it cannot lose sight that the ultimate objective of that flight is to mitigate risk and provide a clear understanding of the risk posture prior to the first crew flight.

– Patricia Sanders, ASAP Chair

The ASAP as recommended NASA doesn’t skip the “green run” integrated test of the SLS core stage – which adds pressure to meeting a 2024 lunar landing time frame. Credit NASA

NASA has yet to formally respond to the recommendation, but it would seem unlikely they’d go against the ASAP. This potentially means that SLS will be unlikely to make its first uncrewed flight – Exploration Mission 1 (EM-1) in 2020, and the ripples may spread further, affecting the time line for the first crewed test of SLS and Orion, and on onwards towards affecting the 2024 goal.

Another issue is that of how NASA will actually get to and from the Moon’s surface. Originally, the agency planned a “two-step” approach to lunar lander development: issue a procurement notice for the development of a lunar lander ascent vehicle, designed to lift a crew off of the Moon tat the end of their say, and a second notice for the transfer and descent stages of the vehicle – presumably allowing different companies to work on the various elements.

To assist NASA in the 2024 goal, Lockheed Martin has re-vamped its Moon lander into a two-stage vehicle, the upper ascent / command module of which will utilise elements from the Orion MPCV craft. Credit: Lockheed Martin

However, on April 26th, NASA altered the procurement notice to seek proposals for a fully integrated lander vehicle. The idea is to speed-up the lander’s design and development and potentially reduce issues of integration of elements built by different contractors.

Certainly, one company that could benefit from this switch is Lockheed Martin, prime contractors for the Orion vehicle, and potential major supplier of the Lunar Orbital Platform-Gateway (LOP-G), the lunar space station seen as a pre-requisite to any crewed landings on the Moon. They first  announced their concept for a fully integrated lunar lander in October 2018, and on April 10th, 2019, the company outlined changes to both their lunar lunar and LOP-G designs in response to the push for s 2024 landing.

The revised Lockheed Martin lunar lander with the ascent / command module mated to the descent / landing stage. Credit: Lockheed Martin

Under their October 2018 plans for a lunar lander, Lockheed Martin proposed building a single, fully reusable vehicle, a 62 tonne (when fully fuelled) behemoth capable of taking 3 or 4 astronauts and a tonne of equipment to / from the lunar surface (by comparison, the Apollo lunar module weighed 16.4 tonnes fully fuelled).

This giant vehicle would support stays of up to 14 or 15 days on the lunar surface, prior to the entire vehicle returning to the LOP-G where the crew would use the Orion to fly back to Earth, while the lander refuelled itself from supplies shipped to the LOP-G and stored there.

However, such a vehicle presupposes the availability of a fully operational LOP-G, and there is simply no way such a facility could be designed, built, launched, assembled in lunar orbit and tested ready for operational use by 2024. This being the case, Lockheed Martin is now proposing a semi-reusable 2-stage lunar lander modelled along the same lines as the Apollo Lunar Excursion Module – although again, much larger.

In the revised design, the new lander would comprise a large descent and landing stage, only carrying sufficient fuel to get the complete vehicle onto the surface of the Moon and carrying various equipment lockers and bins. This would be topped by a combined command / ascent module that will would employ a modified version of the European-built Orion Service Module, complete with main motor and power generation systems, as its lower half. This would serve to propel the module and crew back up to the LOP-G at the end of a surface mission. The command section at the top of the module would include elements from the Orion vehicle for flight control, a dedicate lunar surface command deck and the necessary living space for a crew of around 3 for 14-15 days on the Moon.

Making the lander semi-re-usable means the Lockheed Martin do not need a fully operational LOP-G to support the fully re-usable version of their lander. Instead, a “bare necessities” LOP-G could be placed in orbit around the Moon  – little more than a propulsion / power module and a docking adaptor – in order for lunar missions to commence. These could then proceed whilst the LOP-G is itself built-out to accommodate more advanced missions.

The proposed Lockheed Martin ascent module departs the Moon for a return to the LOP-G. Credit: Lockheed Martin

While this approach would require a new lander for each mission to the surface on the Moon at least until the LOP-G is capable of supporting more ambitious landing vehicles, such as Lockheed’s proposed fully re-usable lander, it would offer a faster track to achieving a crewed landing on the Moon in 2024 by vastly reducing the complexity of building the initial version of the LOP-G. Nevertheless, building, comprehensively testing and deploying both the “bare necessities” LOP-G and the two-stage lander system and having them fit for purpose by 2024 remains a pretty tall order.

The approach also raises the question of whether the LOP-G is actually required – at least initially. Given that each mission to the Moon will require a new lander, the descent stage of each preceding mission having been left on the Moon, there is a question to be answered as to why not fly the early missions a-la Apollo? Just send a combination of Orion and lander directly to the Moon from Earth orbit? The Orion could be “parked” in lunar orbit under automated control, with the lander taking the crew directly down to the Moon. The ascent would then return the crew to the Orion, and could be returned to Earth orbit where it could be refurbished ready for a further flight to the Moon, mated to a new descent stage and along with another Orion. Cargo landers could be launched in a similar way (or even on fully automated landers), allowing supplies and equipment to be delivered directly to the surface of the Moon to allow a base to be established without a lot of tedious mucking about in order around the Moon until something like the LOP-G is really needed.

InSight Update

In March, I wrote about the issues being experienced with the Heat Flow and Physical Properties Package (HP3, deployed on the surface of Mars by NASA’s InSight lander earlier this year. Designed to work its way into the Martian subsurface, in order to measure heat escaping from Mars’ interior and give scientists clues about the planet’s composition and history, the instrument’s self-propelled drill (or “Mole”) hit something solid enough to keep it stuck and slightly canted over after progressing just 30-35cm into the Martian soil.

Scientists are still trying to determine what caused the Mole to stop. A rock is the obvious answer, but maybe not the correct one; another possibility involves the nature of the sand itself, rather than obstructive rocks. In order to hammer its way into the surface, the Mole requires friction between itself and the sand it is hammering into. However, it is thought that the subsurface sand where the Mole is operating might be more compactible than anticipated. So, instead of simply being pushed up and back by the Mole as it drives itself forward, the sand is being push aside and compacted into a hole around the mole, like the shaft of a well, leave a small gap between it and the mole’s side that is sufficient enough to deny it the required friction, leaving it unable to propel itself forward.

Data from recent tests on Mars is currently being assessed to see if this might be the case, or if another cause can be identified. However, at this point in time, scientists remain mystified as to what has happened.

Meanwhile, the seismometer – called SEIS – InSight also deployed to the surface of Mars at the start of 2019 has detected ithe first known seismic tremor on Mars, in a discovery that could shed light on the ancient origins of Earth’s neighbour.

The French space agency CNES, responsible for SEIS, said it had detected “a weak but distinct seismic signal” from the probe on April 6th, 2019 (Sol 128 for the mission), although this rapid result can as something of a surprise. Mars is thought to be largely tectonically dormant, meaning Marsquakes would be very rare compared to those of Earth, and most likely linked to the continual heating and cooling of the planet’s surface. This would, it had been theorised, cause surface expansion and contraction that might eventually result in stress strong enough to break the crust.

We’ve been waiting months for a signal like this. It’s so exciting to finally have proof that Mars is still seismically active. We’re looking forward to sharing detailed results once we’ve had a chance to analyse them.

– Philippe Lognonné, the SEIS team lead

Nevertheless, this is precisely what SEIS may have heard, and while the quake was too small to provide solid data on the Martian interior, it is giving the mission team an idea of how seismic activity on Mars works.

In fact the recording was the second of four SEIS had picked during March and April, the others being on March 14th (Sol 105), April 10th (Sol 132) and April 11th (Sol 133), 2019. However, the other three were so faint, it was impossible to tell the nature of their origin, although they also remain under investigation.

Space Crew Dragon Explodes in Test

A SpaceX Crew Dragon spacecraft suffered what the company said was an “anomaly” during static fire tests of its abort engines on April 20th, 2019, dealing a setback to the company’s plans to fly a crewed test flight to the International Space Station later this year.

The test was focused on the capsule launch abort system, designed to push the vehicle and crew clear of the launch rocket in the event of a malfunction with the latter. In particular, the test was designed to conclude with a firing of capsule’s the eight main SuperDraco engines – and it was at this point that things went wrong, with an explosion being reported. Neither NASA nor SpaceX has given any precise details on the incident or the status of the test vehicle, with SpaceX only giving a brief statement immediately following the accident.

Earlier today, SpaceX conducted a series of engine tests on a Crew Dragon test vehicle on our test stand at Landing Zone 1 in Cape Canaveral, Florida. The initial tests completed successfully but the final test resulted in an anomaly on the test stand.

– SpaceX spokesperson

No-one was injured in the accident, but the vehicle involved was due to be launched via a Falcon 9 rocket this summer in a full flight test of the crew abort system during an uncrewed flight. SpaceX is now working with the Aerospace Safety Advisory Panel (ASAP) to determine what happened, the investigation including “active NASA participation.” The initial work is focused on collecting all the evidence from the test site and creating a timeline of the incident. It is currently too early to tell how this affects future Crew Dragon flights, include the Demo-2 mission intended to fly two astronauts to the space station later in the year.