The lunar bridge: a shortcut to Mars? | Science

SThis time, the race will mark a milestone when NASA celebrates the 50th anniversary of the arrival of American astronauts on the moon. In December 1968, Frank Borman, Jim Lovell and Bill Anders – on Apollo 8 – swept the lunar surface and captured brilliant blue images of the Earth rising above the gray plains of the moon. It was one of the most dramatic space missions ever made. Controlled landings followed, but after a few years, the United States lost interest in lunar space flights.

But now, NASA has revealed its intention to return to the moon and has asked European scientists and industry leaders to join the agency in a bold plan to revive the conquest of the solar system by humanity. in the next decade.

The proposed station, the gateway to the lunar orbital platform – called Gateway – will allow astronauts to develop techniques that will open the lunar surface for exploration and exploitation. At the same time, the station will help humans perfect their survival skills in the deep space, preparing for future manned missions to Mars.

Participation in the construction of the station would cost Europe more than £ 1 billion and the decision to participate will be made at a meeting of European science ministers next year. If ministers agree, the European Space Agency (ESA) – of which the United Kingdom is a key member – would join other international partners that NASA is recruiting for its Gateway project. These include space agencies from Russia, Canada and Japan.

"Essentially, Gateway will be a robotic outpost that will be visited by groups of astronauts – initially for weeks, then months at a time," says David Parker, Director of Human Spaceflight and Robotic Exploration at Esa. . "They will learn to survive in deep space and to deal with problems such as radiation and meteorites. At the same time, they will also be leading robots that will explore the surface of the moon.

A green light for Gateway would also put an end to the hiatus in inhabited space exploration that has lasted for nearly a decade. Since the immobilization of the space shuttle, space flights have been limited to the launch of the Russian space capsule Soyuz, which is used to transport the crew and supplies to the International Space Station and the few missions made by the taikonauts on the ships Chinese space.

Gateway should change that – and it will do so by taking advantage of a major breakthrough in US space engineering that will occur when NASA begins flying with its new Deep Space capsule, Orion, and its launcher, the Space Launch System, in a few years. . These will be the main components of Gateway as well as modules similar to those currently used as stores and crew quarters on the ISS (see box), although NASA insists that Gateway will be considerably smaller than its current space station.

The extraction, from the lunar soil, of minerals, chemicals and, most importantly, water, will be the key to operating their lunar station. "Recent evidence suggests that comets and asteroids have bombarded the moon for billions of years, depositing water – in the form of ice – in its polar regions," said Mahesh Anand, a reader in planetary science and exploration. at the Open University.

Scientists like Anand think it should be possible to use this water to turn the moon into a refueling station for long-term missions to Mars and beyond. The ice would be harvested, melted and electrolyzed – using the energy generated by the solar panels – into its hydrogen and oxygen components. "You could then use this hydrogen and oxygen as liquid propellants," added Anand. "That's what fueled the main shuttle engines after all. Then you could use the moon as a supply post to fly spacecraft to Mars.

This remains a distant goal. For starters, astronomers do not have specific details about the most promising places to find water on the moon. Finding these sources will not be easy, but not impossible – thanks to Gateway. It will orbit the Moon at an altitude of a few hundred kilometers and from there, the astronauts will remotely control the robber robots and send them rolling on the lunar surface to locate the ice-rich areas. Samples could even be returned to the space station by an unmanned spacecraft.

Esa scientists are already working with Canadian and Japanese space agencies to prepare a robot mission called Heracles, which would travel to the moon in the next decade and use the bridge as a transition house to store lunar samples. before being sent back to Earth. "It will be much easier to drive a robot at an altitude of only a few hundred kilometers above the moon than the Earth at 250,000 miles," says Anand. "It only takes a fraction of a second to send a signal and get an answer. On the other hand, it would take several seconds if you are on Earth, making the control of a lunar rover much more difficult.

European astronauts recently guided an automated rover on Earth using commands in the ISS – which revolves around the Earth at about the same height as the gateway would turn around the moon. The technology is already well tested, says Esa.

"The moon has hardly moved for 4.5 billion years," Parker says. "It's a museum of the history of our solar system. And yes, we visited it when we briefly landed the Apollo spacecraft. However, this amounted to going to a museum, going directly to the gift shop and leaving. These are the dusty corners of a museum where we find really interesting things – and that 's where we will go with Gateway.

This point is supported by James Carpenter, member of the lunar exploration team of Esa. "The major scientific impact of Gateway will undoubtedly come from the way it will open access to the lunar surface," he says. "However, many other areas of research will be beneficial.

"We will be able to study the effects of radiation on human physiology; We will be able to collect dust particles from asteroids, comets or possibly objects outside our solar system. We will be able to study the interaction of the sun and the moon with the terrestrial magnetosphere. The gateway would also be ideal for launching tiny CubeSat satellites and other devices that could pave the way for exploration of the solar system. "

Carpenter says Esa recently held a workshop to assess the interest of European scientists in joining Gateway. "About 250 people came and since then we have received a substantial number of proposals to do science on the station. There is tremendous enthusiasm in Europe for this project. This is a real opportunity to do the kind of science that has not been possible before. "

Astronomers also want to use Gateway as a platform for assembling deep-space observatories, particularly to study low-frequency radio waves that could give new perspectives on the primitive universe soon after its birth, 13.8 billions of years. These low frequency waves are difficult to observe near the Earth due to interference from human sources.

In addition, Gateway's location will take it far away from Earth's protective magnetic field and leave astronauts exposed to far more intense radiation than those known on the ISS. This will provide key opportunities to study the long-term impact of human radiation in the deep space. "We will finally translate this experience into human missions on Mars," said William Gerstenmaier, associate director at NASA's Washington headquarters.

This point is supported by Parker. "We have to learn to work for long periods there. The Apollo missions took astronauts into deep space but they lasted only a few days. We are talking about spending months at Gateway in the end and if you want to go to Mars, you will have to spend years in deep space. We must learn to live in our garden – near the moon – before going further. "

According to Carpenter, the critical point about the Gateway project is that it does not depend on new or untested technologies. "Great expertise has been developed in the design and assembly of the International Space Station. We know the risks associated with the construction of a space station and the technologies that will guarantee its success. This makes us very confident that Gateway will happen and that it will work. "

An important question remains, however. If Europe agrees to join NASA at Gateway and be involved in the exploration of the lunar surface, will a European astronaut – possibly British – be able to fly to the moon in a near future? Parker is careful. "It's something we would be aiming for, but [it] depend on negotiations with our international partners.

In short, it may take a little longer to see a Briton head for the moon.

Gateway and Orion: giant steps are what you take …

The key element of the project's Gateway mission will be the Orion capsule, being built by space engineers. It is designed to take a crew of four people beyond the Earth's orbit and into deep space. Orion has two key components: first, a command module to transport astronauts. This is under construction by Lockheed Martin. The second component will be an Orion service module that will provide electricity and propulsion to the main machine. It is developed by the European Space Agency (Esa.

The first manned flight of Orion is scheduled for 2023. Once in service, the capsules will be launched in the space of the new generation of high-powered rockets of the United States, the Space Launch System, designed to send heavy loads towards the moon and the planets. The SLS rockets will also carry the modules that will be assembled to form Gateway in lunar orbit. These will be based on modules – such as the Columba module of Esa – that contain stores, contain research equipment and provide accommodations for the crew currently working on the International Space Station.

Last week, NASA announced that Gateway would be equipped with two modules to house astronauts, one to be provided by the United States and the other by NASA's international partners. The conditions will be tight, nevertheless. As currently envisioned, Gateway will have 1,942 cubic feet of living space, compared to 13,696 cubic feet on the ISS.

"The gateway modules will also have to be much lighter than those of ISS, because they will need to be pushed much further into space," says ESA Director David Parker. "In addition, the modules will be moved in space using ion-propelled rockets rather than chemical rockets. The fuel consumption of ion engines is much lower than that of chemical rockets. Ionic engine versions with the type of thrust we will need for Gateway have not been built yet but are under development and should be ready in time for the construction of the station.