Space Sunday: Moon talk

An artist’s impression of an unpiloted commercial lander leaving a scaled-back LOP-G for a descent to the surface of the Moon ahead of a 2024 human return to the lunar surface.Credit: NASA

On May 13th, 2019, NASA announced that the Trump Administration had requested a US $1.6 billion bump to the space agency’s 2020 budget, to assist it in its efforts to return humans to the Moon by 2024. If approved, the increase will be used by NASA as a “down payment” – or more correctly seed money – that will in particular be put towards studies and projects related to the development of a human-rated lunar lander.

Given just how much needs to be done, US $1.6 billion really isn’t that much; in 2019, NASA was allocated US $4.5 billion of a US $19.2 billion to put towards its lunar efforts, most of which was used in the development of the initial Space Launch System (SLS) rocket and the ongoing work in developing the Orion Multi-Purpose Crew Capsule, with small amounts being allocated to studies such as the Lunar Orbital Platform-Gateway (LOP-G) station, and development of a new generation of lunar-capable space suits.

But these capabilities are just a part of the infrastructure NASA needs to build if it really is to achieve a human return to the Moon by 2024. This includes the LOP-G itself, the need to carry out more extensive robotic exploration of the lunar south pole, the selected location for the landing, the development, testing and deployment of these robot missions, the development of the technologies NASA have touted as being required for a long-term human presence on the Moon (not all of which will be required in the initial phases of the return, admittedly). And, of course, there is the need to develop and test the lunar lander itself.

The Lockheed Martin Orion MPCV Ground Test Article (GTA), a version of the vehicle constructed specifically for testing under simulated conditions to demonstrate the environmental integrity and operational capability of the craft. Credit: NASA / Lockheed Martin

The announcement was used by NASA to springboard a series of new PR videos to help promote their lunar aspirations, including one narrated by William “James T. Kirk” Shatner – are upbeat whilst being light on details. Even so they are useful watching for those wanting to have the agency’s aims painted in the broadest of brush strokes.

Part of this PR drive included the confirmation of the lunar programme’s official title: Artemis. The daughter of Zeus and Leto, Artemis was the Greek goddess of the hunt, the wilderness, wild animals, and chastity, the patron and protector of young girls, and was worshipped as one of the primary goddesses of childbirth and midwifery.

However, in this instance, the most important aspect of Artemis’ legend is that she was regarded as the goddess of the Moon – and the twin sister to Apollo. As such, the name is clearly intended as a way to indirectly echo the can do attitude that marked the Apollo era.

NASA’s plans to send humans to the Moon by 2028 had three parts that could be launched, in part, by commercial rockets, and which used a fully operational LOP-G. If the White House target date of 2024 is to be met, these plans must be vastly accelerated – and NASA budget will require a committed year-on-year increase from the US government. Credit: NASA

With one billion of the additional budget request being specifically for use in lunar lander development, on May 17th, NASA confirmed that it has selected 11 companies to begin studies and initial prototype development of portions of human landers intended for use in the 2024 (and beyond) missions.

Some US $45.5 million has been set aside by NASA in support of all 11 companies, each of which is expected to make its own contribution  – up to 20% of the total cost of their study / prototype programme to the development work. The awards are part of NASA’s Next Space Technologies for Exploration Partnerships (NextSTEP) programme, a series of broad agency announcements that support public-private partnerships to develop technologies needed for NASA’s exploration plans.

The 11 companies selected comprise Aerojet Rocketdyne, Blue Origin, Boeing, Dynetics, Lockheed Martin, Masten Space Systems, Maxar Technologies, Northrop Grumman Innovation Systems, OrbitBeyond, Sierra Nevada Corporation and SpaceX.

Given Lockheed Martin have been working on their own proposals for a lunar lander for some time (see Space Sunday: Moon, Mars, and abort systems), and Blue Origin recently unveiled their own lander, Blue Moon (see Space Sunday: a Blue Moon, water worlds and moving house), their inclusion in the list is unsurprising. Neither is the inclusion of the likes of SpaceX, Boeing, Sierra Nevada Corporation and Northrop Grumman. What is perhaps surprising is the inclusion of start-ups like OrbitBeyond (founded in 2018), which was initially granted a Commercial Lunar Payload Services (CLPS) contract by NASA, allowing it to bid on delivering science and technology payloads to the Moon, rather than being involved in the development of human-rated lander vehicles.

Blue Origin, who recently revealed a full-scale model of their Blue Moon lunar lander, are one of 11 companies selected by NASA to carry out initial work into a human-rated Moon lander. Credit: Blue Origin

The awards require companies to pay at least 20 percent of the overall cost of each study or prototype project, with the work to be completed in six months. To allow the companies to start work immediately, the participating companies are allowed to start work while the contract terms are still being negotiated.

However, it’s not all good news. The 2020 federal budget has yet to be passed by Congress, and on May 16th, the House Appropriations Committee released an updated 2020 federal budget proposal of their own. This includes an additional US $1.3 billion in spending for NASA – but almost none of it is earmarked for NASA’s exploration programmes, which encompass a return to the Moon. Instead, under the House proposal, that programme is effectively cut by US $618 million.

Instead, the additional US $1.3 billion would be directed to programmes that the Trump Administration has systematically cut. These include NASA’s Earth sciences programme (which under the Trump budget would be cut by a further US $151 million in 2020), NASA’s education programs formally known as Science, Technology, Engineering and Mathematics (STEM) Engagement, which the White House has twice attempted to kill, and the space technology programme.

Commenting on their budget proposal, members of the House Appropriations Committee indicated they were not entirely ignoring the White house request for additional funding for NASA’s exploration programme, but rather the plans to return humans to the Moon are so vague as to prevent any endorsement of funding specific to those aims until more concrete information – including the potential total cost of a return to the Moon – have been outlined.

When asked by reporters on what that total bill might be, NASA Administrator James Bridenstine could only reply, “I would love to be able to tell you that.”

Our Shrinking Moon

It’s long been thought that when it formed, the Moon might have been somewhat larger than it appears today, but as it cooled it contracted. As the outer layers cooled, they formed the crust, but as the interior mantle continued to cool and contract, this caused the crust to shrink and crumple, creating thousands of stair shaped cliffs and scarps called thrust faults on the lunar surface.

It had been thought that over the millennia, the cooling of the Moon’s interior had reached a point of equilibrium and the shrinking had largely ceased. ,But a new study suggests that it is actually still continuing. A team of researchers, led by Nicholas Schmerr, an assistant professor of geology at the University of Maryland and Thomas Watters from the Centre for Earth and Planetary Studies, Smithsonian Institution, designed an algorithm to re-analyse seismic data from instruments placed by NASA’s Apollo missions in the 1960s and ’70s. Their analysis provided more accurate epicentre location data for 28 moonquakes recorded from 1969 to 1977.

Schematic of the inner structure of the Moon. Credit: Bryan Derksen

The team then superimposed this location data onto imagery of the thrust faults captured  by NASA’s Lunar Reconnaissance Orbiter. Based on the quakes’ proximity to the thrust faults, the researchers found that at least eight of the quakes likely resulted from true tectonic activity—the movement of crustal plates—along the thrust faults, rather than from asteroid impacts or rumblings deep within the Moon’s interior where the small, molten core interacts with the middle mantle. Although the Apollo instruments recorded their last quake shortly before they were retired in 1977, the researchers suggest that the Moon is likely still experiencing quakes to this day.

We found that a number of the quakes recorded in the Apollo data happened very close to the faults seen in the LRO imagery. It’s quite likely that the faults are still active today. You don’t often get to see active tectonics anywhere but Earth, so it’s very exciting to think these faults may still be producing moonquakes.

– Nicholas Schmerr, study co-author

Astronauts placed five seismometers on the moon’s surface during the Apollo 11, 12, 14, 15 and 16 missions. The Apollo 11 seismometer operated only for three weeks, but the four remaining instruments recorded 28 shallow moonquakes from 1969 to 1977. On Earth, the quakes would have ranged in magnitude from about 2 to 5.

A lunar thrust fault, one of thousands discovered by NASA’s LRO. Credit: NASA/GSFC / Arizona State University / Smithsonian

Using the revised location estimates from their new algorithm, the researchers found that the epicentres of eight of the 28 shallow quakes were within 30.4 km (19 mi) of faults visible in the LRO images. This was close enough for the team to conclude that the faults likely caused the quakes. Schmerr led the effort to produce “shake maps” derived from models that predict where the strongest shaking should occur, given the size of the thrust faults.

The researchers also found that six of the eight quakes happened when the moon was at or near its apogee, the point in the moon’s orbit when it is farthest from Earth. This is where additional tidal stress from Earth’s gravity causes a peak in the total stress on the moon’s crust, making slippage along the thrust faults more likely.

We think it’s very likely that these eight quakes were produced by faults slipping as stress built up when the lunar crust was compressed by global contraction and tidal forces, indicating that the Apollo seismometers recorded the shrinking Moon and the Moon is still tectonically active.

– Thomas Watters, study co-author

Scientists have discovered these wrinkle ridges in a region of the Moon called Mare Frigoris captured by LRO. They add to evidence that the Moon has an actively changing surface. Credit: NASA

LRO has imaged more than 3,500 fault scarps on the Moon since it began operation in 2009. Some of these images show landslides or boulders at the bottom of relatively bright patches on the slopes of fault scarps or nearby terrain. Because weathering gradually darkens material on the lunar surface, brighter areas indicate regions that are freshly exposed by an event such as a moonquake.

Other LRO fault images show fresh tracks from boulder falls, suggesting that quakes sent these boulders rolling down their cliff slopes. Such tracks would be erased relatively quickly, in terms of geologic time, by the constant rain of micro-meteoroid impacts on the moon. With nearly a decade of LRO imagery already available and more on the way in the coming years, the team would like to compare pictures of specific fault regions from different times to look for fresh evidence of recent moonquakes.

For me, these findings emphasize that we need to go back to the Moon. We learned a lot from the Apollo missions, but they really only scratched the surface. With a larger network of modern seismometers, we could make huge strides in our understanding of the moon’s geology. This provides some very promising low-hanging fruit for science on a future mission to the Moon.

– Nicholas Schmerr, study co-author


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