Want to go to Mars? We should mine the moon for rocket fuel first

An artist's impression of a moon colony, dating from 1986. Image: NASA/Dennis M. Davidson

Forty-five years have passed since humans last set foot on an extraterrestrial body. Now, the moon is back at the center of efforts not only to explore space, but to create a permanent, independent space-faring society. The Conversation

Planning expeditions to Earth’s nearest celestial neighbor is no longer just a NASA effort, though the US space agency has plans for a moon-orbiting space station that would serve as a staging ground for Mars missions in the early 2030s. The United Launch Alliance, a joint venture between Lockheed Martin and Boeing, is planning a lunar fueling station for spacecraft, capable of supporting 1,000 people living in space within 30 years.

Billionaires Elon Musk, Jeff Bezos and Robert Bigelow all have companies aiming to deliver people or goods to the moon. Several teams competing for a share of Google’s $30m cash prize are planning to launch rovers to the moon.

We and 27 other students from around the world recently participated in the 2017 Caltech Space Challenge, proposing designs of what a lunar launch and supply station for deep space missions might look like, and how it would work.

The raw materials for rocket fuel

Right now all space missions are based on, and launched from, Earth. But Earth’s gravitational pull is strong. To get into orbit, a rocket has to be traveling 11 kilometers a second – 25,000 miles per hour.

Any rocket leaving Earth has to carry all the fuel it will ever use to get to its destination and, if needed, back again. That fuel is heavy – and getting it moving at such high speeds takes a lot of energy. If we could refuel in orbit, that launch energy could lift more people or cargo or scientific equipment into orbit. Then the spacecraft could refuel in space, where Earth’s gravity is less powerful.

The moon has one-sixth the gravity of Earth, which makes it an attractive alternative base. The moon also has ice, which we already know how to process into a hydrogen-oxygen propellant that we use in many modern rockets.

Roving Luna

NASA’s Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite missions have already found substantial amounts of ice in permanently shadowed craters on the moon.

Those locations would be tricky to mine because they are colder and offer no sunlight to power roving vehicles. However, we could install big mirrors on the craters’ rims to illuminate solar panels in the permanently shadowed regions.

Mining operations on the moon, an artist’s rendering. Image: Sung Wha Kang (RISD)/creative commons.

Rovers from Google’s Lunar X Prize competition and NASA’s Lunar Resource Prospector, set to launch in 2020, would also contribute to finding good locations to mine ice.

Imagining a moon base

Depending on where the best ice reserves are, we might need to build several small robotic moon bases. Each one would mine ice, manufacture liquid propellant and transfer it to passing spacecraft. Our team developed plans to accomplish those tasks with three different types of rovers. Our plans also require a few small robotic shuttles to meet up with nearby deep-space mission vehicles in lunar orbit.

An artist’s rendering of lunar rover concepts. Image: Sung Wha Kang (RISD)/creative commons.

One rover, which we call the Prospector, would explore the moon and find ice-bearing locations. A second rover, the Constructor, would follow along behind, building a launch pad and packing down roadways to ease movements for the third rover type, the Miners, which actually collect the ice and deliver it to nearby storage tanks and an electrolysis processing plant that splits water into hydrogen and oxygen.

The Constructor would also build a landing pad where the small near-moon transport spacecraft we call Lunar Resupply Shuttles would arrive to collect fuel for delivery as newly launched spacecraft pass by the moon. The shuttles would burn moon-made fuel and would have advanced guidance and navigation systems to travel between lunar bases and their target spacecraft.

A gas station in space

An artist’s rendering of a fuel depot for refueling deep-space missions. Image: Sung Wha Kang (RISD)/creative commons.

When enough fuel is being produced, and the shuttle delivery system is tested and reliable, our plan calls for building a gas station in space. The shuttles would deliver ice directly to the orbiting fuel depot, where it would be processed into fuel and where rockets heading to Mars or elsewhere could dock to top up.

The depot would have large solar arrays powering an electrolysis module for melting the ice and then turning the water into fuel, and large fuel tanks to store what’s made. NASA is already working on most of the technology needed for a depot like this, including docking and fuel transfer. We anticipate a working depot could be ready in the early 2030s, just in time for the first human missions to Mars.

To be most useful and efficient, the depot should be located in a stable orbit relatively near both the Earth and the moon. The Earth-moon Lagrangian Point 1 (L1) is a point in space about 85 percent of the way from Earth to the moon, where the force of Earth’s gravity would exactly equal the force of the moon’s gravity pulling in the other direction. It’s the perfect pit stop for a spacecraft on its way to Mars or the outer planets.

Leaving Earth

Our team also found a fuel-efficient way to get spacecraft from Earth orbit to the depot at L1, requiring even less launch fuel and freeing up more lift energy for cargo items. First, the spacecraft would launch from Earth into Low Earth Orbit with an empty propellant tank.

An artist’s rendering of a solar electric propulsion tug above an asteroid. Image: NASA.

Then, the spacecraft and its cargo could be towed from Low Earth Orbit to the depot at L1 using a solar electric propulsion tug, a spacecraft largely propelled by solar-powered electric thrusters.

This would let us triple the payload delivery to Mars. At present, a human Mars mission is estimated to cost as much as $100bn, and will need hundreds of tons of cargo. Delivering more cargo from Earth to Mars with fewer rocket launches would save billions of dollars and years of time.

A base for space exploration

Building a gas station between Earth and the moon would also reduce costs for missions beyond Mars. NASA is looking for extraterrestrial life on the moons of Saturn and Jupiter. Future spacecraft could carry much more cargo if they could refuel in space – who knows what scientific discoveries sending large exploration vehicles to these moons could enable?

By helping us escape both Earth’s gravity and dependence on its resources, a lunar gas station could be the first small step toward the giant leap into making humanity an interplanetary civilization.


The authors of this article were: Gary Li, Ph.D. Candidate in Mechanical and Aerospace Engineering, University of California, Los Angeles; Danielle DeLatte, Ph.D. Student in Aeronautics & Astronautics, University of Tokyo; Jerome Gilleron, Ph.D. Candidate in Aerospace Engineering, Georgia Institute of Technology; Samuel Wald, Ph.D. Student in Aeronautics and Astronautics, Massachusetts Institute of Technology; and Therese Jones, Ph.D. Candidate in Public Policy, Pardee RAND Graduate School.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

Brexit is an opportunity for cities to take back control

Leeds Town Hall. Image: Getty.

The Labour leader of Leeds City Council on the future of Britain’s cities.

As the negotiations about the shape of the UK’s exit from the EU continue, Britain’s most economically powerful cities outside London are arguing that the UK can be made stronger for Brexit – by allowing cities to “take back control” of service provision though new powers and freedoms

Core Cites UK, the representative voice of the cities at the centre of the ten largest economic areas outside London, has just launched an updated version of our green paper, ‘Invest Reform Trust’. The document calls for radical but deliverable proposals to allow cities to prepare for Brexit by boosting their productivity, and helping to rebalance the economy by supporting inclusive economic growth across the UK.

Despite representing areas responsible for a quarter of the UK’s economy and nearly a third of exports, city leaders have played little part in the development of the government’s approach to Brexit. Cities want a dialogue with the government on their Brexit plans and a new settlement which sees power passing from central government to local communities.

To help us deliver a Brexit that works for the UK’s cities, we are opening a dialogue with the EU Commission’s Chief Negotiator Michel Barnier to share our views of the Brexit process and what our cities want to achieve.

Most of the changes the Core Cities want to see can already be delivered by the UK. To address the fact that the productivity of UK cities lags behind competitors, we need to think differently and begin to address the structural problems in our economy before Brexit.

International evidence shows that cities which have the most control over taxes raised in their area tend to be the most productive.  The UK is significantly out of step with international competitors in the power given to cities and we are one of the most centralised countries in the world.  


Boosting the productivity of the UK’s Core Cities to the UK national average would increase the country’s national income by £70-£90bn a year. This would be a critical boost to the UK’s post-Brexit economic success.

Our green paper is clear that one-size fits all policy solutions simply can’t deal with the complexities of 21st century Britain. We need a place-based approach that looks at challenges and solutions in a different way, focused on the particular needs of local communities and local economies.

For example, our Core Cities face levels of unemployment higher than the national average, but also face shortages of skilled workers.  We need a more localised approach to skills, education and employment support with greater involvement from local democratic and business leaderships to deliver the skills to support growth in each area.

The UK will only make a success of Brexit if we are able to increase our international trade. Evidence shows city to city networks play an important role in boosting international trade.  The green paper calls for a new partnership with the Department of International trade to develop an Urban Trade programme across the UK’s cities and give cities more of a role in international trade missions.

To deliver economic growth that includes all areas of the UK, we also need to invest in our infrastructure. Not just our physical infrastructure of roads, rail telecommunications and so forth, but also our health, education and care infrastructure, ensuring that we are able to unlock the potential of our core assets, our people.

Whether you think that Brexit is a positive or a negative thing for the UK, it is clear that the process will be a challenging one.  Cities have a key role to play in delivering a good Brexit: one that sees local communities empowered and economic prosperity across all areas of the UK.

Cllr Judith Blake is leader of Leeds City Council.