What engine technology could get us to Mars faster?

NASA aims to put a man on Mars by 2033. How we get there is much less certain!
Mars 2020 Rover
The Mars 2020 Rover will launch when the planets are closest, in July-August 2020. Image: NASA

The Mars Mission

NASA plans to launch a rover this coming year to land on Mars. This is part of the Mars Exploration Program.

In July/August 2020, the rover will launch from Cape Canaveral in Florida. The flight time will take about six months. The mission will last at least one Mars year (687 Earth days), and the rover is equipped with a drilling apparatus to take samples of the soil and minerals on the red planet.

Longer-term, the aim is to send astronauts to Mars in 2033. However, an analysis by the IDA Science & Technology Policy Institute deems this unlikely.

Space travel – the challenges

Even beginning to try and summarise the technological feats that have gotten mankind this far into space is impossible. It is a fascinating area of research challenging some of the greatest scientists in the world.

However, in a nutshell we are talking about massive journey times. It will take the Mars 2020 rover six months to reach Mars – and it weighs about the same as a small car, and does not need to sustain life.

The distance between Earth and Mars changes according to their orbits. It varies between 54.6 million km and 401 million km, hence the rover launch being planned for a time when the distance is lowest.

Mars Science Laboratory Rover
The Mars Science Laboratory Rover landed on Mars in 2012. Image: NASA

Engine troubles

Currently, we use chemical rockets to travel through space. Chemical propulsion cannot last long enough to manage the longest space exploration trips.

Spokespeople for Boeing and Lockheed Martin think we should stick with what we know.

The BBC reports that a Boeing Rocket Propulsion Specialist, Rob Broeren, says ‘the nice thing about going with highly proven technologies is that you have full confidence that they definitely work. With new technologies, they sound good on paper, but when it comes to implementing them, you will run into issues that will delay you.’

There are other engines in different stages of development that might take over. Let’s take a look at the options!

Solar electric propulsion

This sounds a bit like magic to me! Using solar power would take a lot longer than chemical rockets, but the concept is to send equipment and supplies ahead of astronauts. They would then travel in much lighter spacecraft to meet with their supplies.

It works by capturing solar energy through large solar arrays. This is then converted into electricity. The general consensus seems to be that there is more work to do on developing solar electric propulsion, but at the moment is too slow to make it a viable option.

Dale Thomas, Professor at the University of Alabama in Huntsville (UAH) sayssolar electric works well for smaller payloads, but we’re still having trouble getting it to scale‘.

Curiosity rover landing via sky-crane
The Mars rover 2020 will use the same sky-crane descent as used when landing the NASA Curiosity rover. Image: NASA

Nuclear thermal electric propulsion

A different option is to use chemical rockets for take-off and landing but to switch to nuclear thermal electric propulsion for the duration of the journey.

With this tech, a small nuclear reactor heats liquid hydrogen, and the gas then shoots out of the thruster creating the propulsion.

The big problem here is, of course, potential exposure to radiation. There is already an inherent exposure risk to astronauts going into space, so to increase this risk is not something to be taken lightly.

Another issue is that it is extremely challenging to test a nuclear engine in Earth, due to the dangerous emissions.

Joe Cassidy is Executive Director of Aerojet Rocketdyne’s Space Division. He says that if ‘we can cut transit time down by 30-60 days, it will improve the exposure to radiation facing the crew.

Electric ion propulsion

The third idea is electric ion propulsion, which uses electricity to generate propulsion by accelerating ions consisting of charged atoms or molecules.

This technology is currently too low power to conduct fast journeys, or to transport heavier spacecraft containing astronauts. The propulsion is low, but over time can reach higher speeds.

The consensus

Space travel is gaining traction fast, and I am excited to see what the next few years may bring. With private sector companies lending their budgets and R&D department to the cause, it feels like a race against time.

As for a consensus, it seems there really isn’t one yet!

Ad Astra, led by former NASA astronaut Franklin Chang Diaz, are building Vasimr. This is a thruster that uses radio waves and a magnetic field to innovate electric ion propulsion. The Vasimr would use solar electric propulsion for smaller craft.

Lockheed Martin, who built the new X-59 QueSST super speed aircraft, are focusing on solar electric propulsion.

Nuclear thermal electric propulsion is widely seen as the most viable technology that is closest to being live tested.

It isn’t clear yet which technology will prove to be successful. But, I think that it is only a matter of time before the first manned Mars mission is announced. Keep an eye out, the future is in the stars.

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