Lunar lift-off

National space agencies and private companies are preparing missions that will return humans to the surface of the Moon, 50 years on from the successful landing of Apollo 11. Why go back, and what might the new crewed lunar missions involve? Stuart Nathan reports

A NASA rendering of how an Artemis lunar module might look

 The jury is out on whether Donald Trump believes the Moon is part of Mars. Recently, the most consistently puzzling US president in history tweeted that “We shouldn’t be going back to the moon, we did that 50 years ago. We should be aiming for bigger targets like Mars (of which the moon is part).”

Charitable observers interpreted this as displaying Trump’s understanding that plans to return crewed missions to the lunar surface are part of a larger goal of landing humans on the Red Planet. Others, more cynical, expressed glee at Trump seeming to display an alarming degree of ignorance.

Either way, half a century on from the Apollo missions, plans are indeed advanced to send men (and probably women as well, this time) to the Moon, with several organisations now trying to design missions.

The establishment of an office at NASA called ‘Moon to Mars’ confirms that the plan is to use new lunar missions as a stepping stone to our nearest planetary neighbour. The lure of humans on Mars – even if it’s only as a romantic gesture rather than scientific – is a strong one, and visiting the Moon represents a perfect dress rehearsal. It’s much closer than Mars (a week’s return journey rather than two years, and therefore technically simpler), but it offers the chance to develop, test and optimise many of the systems that will be needed for the longer trip.

But proponents of Moon missions argue that Mars preparation and rehearsal is not the only reason for a lunar return. We have unfinished business with our satellite. Some of these new reasons are scientific – continuing the interrupted studies of the Apollo teams taking into account improved analytical capabilities developed over the intervening years and both investigating and developing theories about the Moon’s origins, geology and composition.

If Donald Trump does believe the Moon is Martian, he’s wrong; but it might be partly terrestrial. A current theory states that the moon was created when a large object collided with the still-molten Earth in the early stages of the solar system, ripping away a chunk of material. The Moon is composed of remnants from that ancient collision, the theory continues. If this is the case, it will contain the same mix of elements that is found on Earth and will provide clues to the subsequent development of the planet, as well as revealing how the solar system, and other planetary systems in the galaxy, developed.

Whatever the justification for the new lunar race, it differs from the 1960s version in one important respect: there is no plan on the horizon to send Russians to the Moon, or at least not one that has been made public. But, like the 1960s, the Americans seem set to lead the charge. In March this year, vice-president Mike Pence announced that NASA was being tasked with returning astronauts to the Moon by 2024.

The four commercial lunar landers selected by NASA will carry out preparatory studies for Artemis missions

Apollo to Artemis

While Apollo was the watchword for the first lunar missions launched by NASA, the second iteration of government-backed crewed Moon journeys will carry a different name: Artemis.

It’s a fitting name; in Greek mythology, Artemis was the twin sister of Apollo. While Apollo was a solar deity, Artemis was always associated with the Moon.

It seems that NASA is determined to cement the Artemis name in the public eye early. It has redesignated the missions to be undertaken to test the Orion capsule, its new crew-rated module, from their original names of Exploratory Mission 1 (EM-1) and EM-2, the launch of the capsule for the first time with and without astronauts on board, as Artemis-1 and -2.

Artemis-1 is scheduled for July 2020: it will be the first flight of Orion atop the new space launch system (SLS) rocket, based on systems originally developed for the Space Shuttle. It will be a 10-day mission that will catapult an empty Orion capsule around the moon, returning directly to earth. Artemis-2, scheduled for 2022, will be another SLS launch, this time sending a crew on a lunar orbital trip (this would be the equivalent of 1968’s Apollo 8 mission, which was the third flight of the Saturn V launcher).

There will then be a pause in the Artemis programme while the first units of the Deep Space Gateway (DSG) space station are placed into position. The initial plan is for only the power and propulsion modules, along with the key elements for a subsequent lunar landing – currently envisaged, initially at least, to be a three-module vehicle – a transfer module, a descent module and a return module. All of these would be expendable.

These missions would be undertaken by commercial launch service providers, and once the modules are in position, Artemis will resume. Scheduled to launch in 2024, Artemis-3 will send a crew in an Orion module to rendezvous with the DSG, where its crew will transfer into the lunar modules. These will be launched to lunar orbit, from where the descent and return modules will detach to take the crew to the Moon’s surface. The landing site is currently planned to be near the lunar south pole, a location of intense interest because it is believed to harbour water ice deposits in sections of craters that are in permanent shade, where temperatures drop are continuously below -100°C.

As with Apollo, the descent module will remain on the moon, while the return module will detach to dock with the transfer module in orbit. The return and transfer modules will fly back to the DSG. The crew will then disembark from their lunar shuttle back into Orion, which will return them to Earth. This differs somewhat from the Apollo approach, which used the conical command module and its attached cylindrical service module as the vehicle to go all the way from Earth into lunar orbit. For Artemis, the command and service modules for crewed missions will not go to the Moon, and there will be no need for the Artemis-3 SLS to also carry a LM (lunar module), as was the case with Apollo. This will save on its launch weight.

The Apollo LM is so far the only vehicle to have ever taken humans onto the moon and was developed and built by Grumman Aerospace, now part of Northrop Grumman. The company won the contract after 11 companies were invited to bid, with the process beginning in 1962.  Once again, the builder of the Artemis LM (which might not be called that; it currently has no official designation) will be decided by a competitive bidding process. This began in May of this year, making the deadline somewhat quicker than in Apollo’s case.

A rendering of Blue Origin’s proposed lunar cargo lander

Again, 11 companies have been invited to conduct studies and select prototypes for a prospective lander. Each is looking at a slightly different project, and the scope of these projects indicates that NASA is intending missions after Artemis-3 to be somewhat different, as they include reusable modules that may be refuelled between missions back at the DSG. The 11 are:

  • Aerojet Rocketdyne, a rocket and missile manufacturer based in Sacramento, undertaking a single transfer vehicle study;
  • Blue Origin (the commercial space company owned by Amazon billionaire Jeff Bezos), carrying out studies of one descent element, and one transfer vehicle, and producing a prototype of a transfer vehicle, as well as planning its own missions to the Moon both with and without crews using its own New Glenn launcher system in the coming decades;
  • Boeing, looking at a descent element study, two descent prototypes, one transfer study and prototype, and one refuelling element study and prototype;
  • Dynetics, a Huntsville, Alabama-based company formed in the 1970s with close links to NASA, producing one descent element study and five descent prototypes;
  • Lockheed Martin, undertaking one descent element study, four descent prototypes, one transfer vehicle study, and one refuelling element study;
  • Masten Space Systems, a Californian company previously specialising in reusable launchers, doing a single descent element prototype;
  • Northrop Grumman, looking at one descent element study, four descent element prototypes, one refuelling element study and one refuelling element prototype;
  • OrbitBeyond, a New Jersey-based specialist in lunar technologies founded only last year, producing two refuelling element prototypes;
  • Sierra Nevada Corporation, an established electronics company heavily involved in satellite technologies, carrying out one descent element study, one descent element prototype, one transfer vehicle study and prototype, and one refuelling element study;
  • SpaceX, Elon Musk’s space company, which has been collaborating with NASA for some years on commercial launches, including resupplying the international space station, perhaps surprisingly only producing one descent element study;
  • SSL, a Californian company specialising in building communication satellites, producing one refuelling element study and prototype.

The projects are taking place as part of NASA’s NextSTEP (Next Step technologies for Exploration Partnerships) programme, a public-private partnership aimed specifically at commercial development of more extensive crewed missions between the Earth and the Moon and beyond. NextSTEP projects include advanced propulsion, such as electric systems, and habitation systems intended to be part of the ongoing DSG project, which will continue to be developed after Artemis-3 as it is intended to be the launch site for the vessel that will eventually take explorers to Mars, planned to be in a reusable ‘cruiser’ that will be assembled and possibly even entirely partially or manufactured off-planet.

 The Engineer covered the background to, and the planning of, this project in depth in 2017.

The NextSTEP approach is intended to the process of developing equipment. “Our team is excited to get back to the Moon quickly as possible, and our public/private partnerships to study human landing systems are an important step in that process.” said Marshall Smith, director for human lunar exploration programs at NASA Headquarters.

According to Greg Chalvers, human landing system formulation manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama, the philosophy behind Artemis is for NASA itself to not develop the details of how astronauts will be taken to and landed on the lunar surface itself. “This new approach doesn’t prescribe a specific design or number of elements for the human landing system,” he said. “NASA needs our system to get the astronauts on to the surface and get them home safely, and leaving a lot of the specifics for our commercial partners.”

The other contenders

The other nation states aiming to reach the moon with crews in the coming decades are China and India, but their plans are not as advanced as those of the US. The Chinese Chang’e Project has four well-defined phases – orbital missions, soft landers and rovers, sample-return and establishment of a lunar research station.

These in fact began in 2007 with a lunar orbiter (Chang’e 1). Three subsequent missions have seen a second orbiter, and two landers plus rovers successfully sent to the lunar surface.

Chang’e 5, a sample-return mission, is planned for launch in December of this year, targeting the Mons Rümker volcano in the north-east of the Moon’s near side. Looking forward, China does intend to undertake a crewed landing (in their case, the human explorers will be taikonauts), but the schedule does not see this happening until the 2030s, again near the south pole, where the plan is to establish a permanent outpost.

India, meanwhile, has the moon in its near sights. The Chandrayaan-2 mission is scheduled to launch between 9 and 16 July, taking an orbiter, lander and Rover to a site near the south pole with a landing scheduled in September, and explorations plans to ascertain the nature of the terrain and the composition of any minerals or compounds on the surface. In January of this year, the chairman of the Indian Space Research Organisation, Kailasavadivoo Sivan, stated that he aims to launch an Indian crewed lunar mission by December 2021, following an announcement by prime minister Narendra Modi last year. This would make it the first nation to return humans to the moon by some distance (in this case, the moonwalkers would be called vyomanauts).

The drill for ESA’s lunar in situ resource utilisation mission will be based on the ExoMars rover drill, seen here being tested

Europe is not planning its own human voyages to the Moon, but is involved on the technology side. The main goals of European lunar projects are oriented towards in-situ resource utilisation (ISRU), the harvesting, refining and direct use of materials found in space for the furtherance of human exploration. James Carpenter, strategy officer in the directorate of human and robotic exploration and the European Space Agency, explained that the reasoning for this is purely practical. “We can’t carry everything that we are going to need,” he told The Engineer. “Especially as we aim to venture further into the solar system, ISRU is the only way we are going to be able to do it.”

At the moment, the main goal of ISRU is to generate oxygen. “That has two immediate applications,” Carpenter said. “It can be used as fuel, and astronauts can breathe it. We also already know that on the Moon there are compounds that contain oxygen: oxide minerals and water ice, although at the moment we don’t fully understand where they are and in what precise quantities. ESA investigations are aiming to gather more information on both, as well as investigating the best ways of extracting the oxygen.”

Much of the technological inspiration for these efforts is coming from the ExoMars programme, whose rover, named Rosalind Franklin, is currently under development.

Rosalind will prospect for signs of past life and chemicals that might have supported it on the surface of Mars on a mission launching next year. The ExoMars drill, a percussive device designed to penetrate some 2m into the Martian surface, is the model for a similar instrument designed to go to the Moon in a project called PROSPECT (Package for Resource Observation and in Situ Prospecting for Exploration, Commercial exploitation and Transportation) which could fly to the Moon on a Russian mission, Luna-27, which aims to explore the south pole on the far side in 2024.

PROSPECT will consist of a lander incorporating a drill, called ProSEED, which will be designed to penetrate 1m below the surface to extract samples of water ice and volatile compounds that are solid at temperatures between -150°C and -200°C. These samples will then be passed to an on-board laboratory called ProSPA, that will heat the samples to extract the volatiles and will be able to carry out experiments involving heating up to temperatures of 1000°C, to test processes that might be used to extract oxygen in the future.

As well as utilisation by human missions, these experiments will provide information on the possible origins of compounds including water in the earth-moon system. Carpenter said: “We still don’t know where the Earth got most of its water from.

“And if we understood that, we might know where else it might be found in the solar system. As it is a source of fuel, that would be extremely useful to help plan exploration into the outer planets and their systems of satellites, which are entire worlds of their own.”

The possibility of using the Moon as a source of minerals that could be useful on Earth has been raised, but ISRU missions are likely to be confined to the use on the bodies where they occur, as transporting them back to Earth is a big task and very much dependent on the abundance and location of deposits.

“We know that helium-3 occurs on the Moon, and has been suggested as a fuel for nuclear fusion, but as we haven’t cracked fusion on Earth it seems foolish to be looking that far ahead just now,” Carpenter said.

“One advantage for Europe in lunar missions is that there is now so much interest from different agencies that we are no longer dependent purely on the Americans and Russians to hitch rides on their missions.

“We know that powerful launchers, to which Europe does not have its own access, will be going there and we have a variety of established relationships with those operators. Knowing that ISRU is going to be vital as humans proceed beyond the Moon, to Mars, and possibly into the asteroid belt, we plan to use the expertise we will establish with our lunar ISRU missions to keep exploring.”

As the UK is leading the ExoMars project, with Rosalind Franklin being assembled and its systems integrated in Stevenage, it seems likely that British institutions will continue to have a key role in this aspect of lunar exploration.