With the announcement of the heavy lift Space Launch System (SLS), NASA has funding and clear direction to build a big rocket and the Orion Multi-Purpose Crew Vehicle (MPCV) to carry a crew of four for 28 days. But if you look more closely, the agency needs to flesh out its technology portfolio quite a bit to get into the deep space exploration business. There are a lot of Powerpoint proposals floating around and some trial projects to further develop all the tools needed to go the Moon, an asteroid, or Mars.

More efficient propulsion is at the top of the list. The hard-core rocket guys want a nuclear engine, but there's not a lot of urgency in the current Administration or in Congress to get into a project which will torque off environmentalists. Solar electric propulsion – using solar panels to generate electricity, then applying it to a steady/constant thrust – is currently on the table.   Earlier this month, NASA awarded contracts to Analytical Mechanics Associates, Ball Aerospace, Boeing, Lockheed Martin, and Northrop Grumman (News - Alert) to develop a report to define a mission concept for demonstrating the infrastructure; each individual contract is worth up to $600,000.

A solar-electric “space tug” could move payloads from low earth orbit (LEO) to higher orbits and beyond, depending on how much fuel you load in and how big the payload is. Operating around Earth, a smaller tug could be used to move around and service satellites between LEO and geosync orbit. NASA would like to have a demonstration mission to test and validate key capabilities and technologies towards a future 300 kilowatt vehicle.

While Orion will support a crew of four for 28 days, that's only enough for a crewed servicing mission for a satellite or a month-long stay to the moon. An asteroid trip may take up to six month while going to Mars is expected to be a round-trip mission up to 440 days or longer. A deep space habitat or “hab” is needed to provide more living space and carry life-support, plus food and water.

Hab designs typically start by using demonstrated elements in use at the International Space Station (ISS) and then adding a life support system capable of operating for long periods of time without a lot of maintenance and breakable parts; hard to get spares when you're in orbit around Mars. The European Space Agency has suggested it could evolve its Automated Transfer Vehicle (ATV) into a deep space exploration module.

It is development of a robust life support system – ECLSS in NASA-speak – which could prove to be the hardest challenge on long space missions. The system needs to be as closed as possible, recycling air and water and requiring little (if any) other supplies. Consuming even a pound a day of something adds up on long space missions, because you have to 1) carry around all those consumable pounds until you use them and 2) burn more fuel to move the consumable pounds.