NASA is planning to send humans to Mars in the next thirty years.

But, what kind of fuel will they use to get there, what will they do if they find life and why are they going?

Engineers from NASA and its partners Orbital ATK, Boeing, Aerojet Rocketdyne and Lockheed Martin took part in an Ask Me Anything session on Reddit to answer questions about the project.

Here are eight things you might not have known about the Mars mission and the scientists behind it.

What kind of fuel and how much of it will be needed to get there?

The type of fuel is really dependent on which part of the propulsion system you are looking at.

For example, the core stage uses liquid hydrogen and oxygen. The boosters use solid propellant. Solar electric propulsion systems are being strongly considered for in-space propulsion.

How much fuel again depends on the type of propulsion, but suffice it to say it's millions of pounds to get out of earth orbit and thousands and thousands to transit to Mars. - Mark Tobias, Orbital ATK

This may sound silly, but are there any plans in case life is found underground during the mission that may compromise the safety of the crew? How long would an emergency evacuation take?

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NASA takes planetary protection very seriously. Any indication of extant life from robotic precursor missions will severely limit approach by future human crew or robotic rovers.

We won't mess around until we are sure it is safe. - Joe Cassady

Any chance you can do better than first manned landing by 2039?

Current funding plans enable the 2039 landing. There are no technology barriers to landing in 2033 or 2035. - Rick Bottomley and Darby Cooper, Boeing.

What is one thing you don't understand and completely blows your mind?

The multiverse. I can't imagine that somewhere in a parallel universe there is another me who is sitting on a beach instead of doing a Reddit! - Bill Pratt, Lockheed Martin

I wish there was only one thing I didn't understand. I'd like to know why Mars lost its atmosphere, its magnetic field, and its liquid surface water ... could this happen to us on Earth? That's why I think we need to explore Mars. - Joe Cassady, Aerojet Rocketdyne

Women. And I've been married for 29 years. - Andy Schorr, NASA

NASA has already sent rovers to Mars. ( AFP: NASA/JPL-Caltech/MSSS )

In the movie The Martian, a large storm forced the crew to evacuate. Would it not be a good idea for the crew to dig and build an "underground bunker" for them to store important instruments and seek shelter in case a similar event took place?

The Martian was fantastic for scientific and engineering accuracy, but, the wind storm was the largest glaring error, thankfully over quickly and easily forgiven.

The atmosphere is so thin on Mars that a windstorm as portrayed is not possible.

Even at 100 miles per hour, the wind of Mars would be equivalent to around a 10 miles per hour Earth breeze in terms of aerodynamic pressure.

So, a windstorm alone would not need such serious action to be taken. But the dust devils seen in the movie are very real phenomena captured by rover cameras! - Nujoud Merancy, NASA

Are there any fears of contaminating Mars by landing a manned mission, especially if there are plans to produce water and oxygen, or is that the plan - to colonise Mars by cultivating aerobic bacteria and plants to kick-start an ecosystem

Great question! With the recent discovery of flowing water this issue is a hotly debated topic. Any human mission will take along our "bugs". If we explore, we will impact the Martian environment in a limited way.

If we colonise, we will have to change the Martian environment to survive. - Joe Cassady

Artist's concept of human colony on Mars. ( John Frassanito and Associates/NASA )

I'm interested in doing stuff like this when I grow up. What classes should I take in high school and what major should I pursue to get a career in this field?

Much of what we do at NASA involves engineering and science. You should consider taking as many science and math courses as possible such as physics, chemistry, biology, earth science, algebra, trigonometry, statistics and my favorite, calculus.

These classes will help you prepare for a degree in science and/or engineering.

Internships in science and engineering are also a great way to learn more about a potential career. - Shawn Quinn, NASA

What's the main purpose of going to Mars? Is it for human expansion or military advancement? Also, is Mars the best destination for our first mission? Was it picked due to distance or actual factual data supporting [its] ability to be able to harbor life?

The reasons for human space travel can be very personal and well as practical. History teaches us that nations who have stopped exploring fade from the world stage.

Meeting the challenge of exploring and overcoming the risks associated with it make us better and world leaders.

In this journey, we develop a whole cadre of technology that benefits everyone, even here on earth. - Mark Tobias