The Proving Ground and the Path to Mars
For 40 years astronauts have depended on Earth for resupply and operational support. Many missions aboard spacecraft like the Apollo capsules or space shuttles lasted only days or weeks. Typical stays aboard the International Space Station, in low-Earth orbit, are six months. Crews aboard the space station can return to Earth in a matter of hours in the case of an emergency. We call these missions “Earth Reliant.”
Testing aboard the space station is helping us develop ways to break these Earth-reliant bonds, so astronauts can be more autonomous the farther into the solar system they explore. The ARM robotic mission and crewed mission to explore the asteroid will further advance these capabilities in the “Proving Ground” between Earth and Mars, or what we call cis-lunar space—the area around the moon.
The deep space environment around the moon is different than low-Earth orbit, but very similar to what an Orion spacecraft would experience on the trip to and from Mars. For instance, solar and cosmic radiation is more prevalent and there are more micrometeorites to shield against.
Transit times to and from Earth are greater as well, and would vary from nine to 11 days for crew and 10-100 days for cargo, with our existing technology. This makes cis-lunar space ideal to test capabilities needed for the longer duration missions to Mars or its moons—the Mars system—where there are fewer ties with Earth.
A human mission to and from the Mars system could last 500 days or longer, including six to nine months of transit each way. Missions to Mars will need to be “Earth Independent.” To become Earth independent, NASA will develop and test through ARM a number of new technologies and capabilities that will directly enable future missions to Mars.
Solar Electric Propulsion
Artist’s concept of a space vehicle powered by Solar Electric Propulsion. Solar Electric Propulsion (SEP) technologies is an essential part of future missions into deep space with larger payloads. Image Credit: NASA
Using advanced Solar Electric Propulsion (SEP) technologies is an important part of future missions to send larger payloads into deep space and to the Mars system. Unlike chemical propulsion, which uses combustion and a nozzle to generate thrust, solar electric propulsion uses electricity from solar arrays to create electromagnetic fields to accelerate and expel charged atoms (ions) to create a very low thrust with a very efficient use of propellant. When compared to conventional chemical propellant sources, the ARM mission uses five to 10 times less propellant as a result of the SEP technology.
The robotic mission to capture and redirect an asteroid will test the largest and most advanced SEP system ever utilized for space missions. It also will test how the Orion spacecraft, launched by a Space Launch System rocket, can dock and operate with a SEP-powered spacecraft. This new technology will help send the large amounts of cargo, habitats and propellant to Mars in advance of a human mission.
Trajectory and Navigation
As we learn to maneuver a large mass like an asteroid using low-thrust propulsion and the gravity fields of Earth and the moon, we’ll prove valuable technologies for the future Mars missions. Human missions to Mars will require far more cargo at a long distance from Earth—much greater than the amount of cargo we currently send to the space station, which takes about one to three days to arrive. The ARM mission will help perfect techniques for sending those large masses to Mars by requiring a precise set of maneuvers to intercept the asteroid at a distance with large time delays. Reaching the Earth-moon system also requires precision very similar to that required for Mars orbit. Very careful power balancing and attitude control will be required to execute this portion of the ARM mission, which will parallel the work needed to pre-position cargo at Mars.
Additionally, the crewed mission aboard Orion to the asteroid in cis-lunar space calls for a complex set of maneuvers to rendezvous and dock with the robotic spacecraft. Both the out-bound legs and in-bound legs of the journey require a critical lunar gravity assist burn, which is executed about 62 miles (100 km) above the lunar surface. The insertion and departure from the distant retrograde orbit also require very precise maneuvers that are comparable to the Mars orbit insertion and Mars departure burns.
Advances in Spacesuits
Picture of astronauts operating in NASA’s Neutral Buoyancy Lab. NASA astronauts Stan Love and Stephen Bowen practice microgravity techniques using the new space suits and tools in the Neutral Buoyancy Lab at Johnson Space Center. Image Credit: NASA
Some of the spacesuit systems NASA uses today aboard the International Space Station were first designed 40 years ago and require regular cargo resupplies from Earth. These spacesuits, known as EMUs (Extravehicular Mobility Units), are truly engineering masterpieces – but they were not designed to be easily maintained by the crew, and are typically returned to Earth. Spacesuits designed to operate in deep space and for the Mars surface will require upgrades to the primary life support system (PLSS). For example on Mars, a carbon dioxide atmosphere exists rendering the current PLSS’s cooling technology obsolete.
NASA is working on an advanced PLSS that will protect astronauts on Mars or in deep space by improving carbon dioxide removal, humidity control and oxygen regulation. The cooling system also is being redesigned to accommodate fluids stored in space for long periods of time and at a slightly elevated atmospheric pressure, similar to the Mars surface environment. We’re also improving mobility by evaluating advances in gloves to improve thermal capacity and dexterity. Finally the PLSS is being designed so that it will last a long time, and can be repaired by crew members in space or on Mars. Astronauts will test the advanced PLSS as they perform these early exploration spacewalks to collect asteroid samples during the crewed portion of the ARM mission.
Sample Collection and Containment Techniques
Asteroids are the left over building blocks of the solar system—pristine pieces of the matter that formed our sun’s planets and their moons. Astronauts aboard the Orion spacecraft will take samples of the redirected asteroid and bring them back to Earth for scientific evaluation and study. Additionally, the interaction with the asteroid could provide data on the internal structure of the asteroid and the answer many long-debated questions about their composition. Some asteroids may contain resources future astronauts could use to extract water and breathable air, create rocket fuel, or even use for 3-D printing.
This experience will help also allow NASA prepare to return samples from Mars through the development of new techniques for safe sample collection and containment. These techniques will ensure that humans do not contaminate the samples with microbes from Earth, while protecting our planet from any potential hazards in the samples that are returned. Additionally, techniques to mitigate dust exposure to the spacesuits, the primary life support system, and the interior of the Orion spacecraft, will be useful for dealing with Martian dust.
Rendezvous and Docking Capabilities
Future human missions to Mars will require new capabilities to rendezvous and dock spacecraft in deep space. We will advance the current system we’ve developed with international partners aboard the International Space Station—the International Docking System. A mission to Mars could require us to stage several vehicles in cis-lunar space first, like habitats or cargo modules. Astronauts could then dock with these vehicles before starting their journey to Mars. Astronauts landing on Mars will also need to re-dock with their Orion spacecraft for the return trip home.
Through the ARM mission, NASA will develop new sensor systems to allow for this kind of rendezvous and close approach, and the mechanical and electrical systems to join the two spacecraft together. These will be critical components of any future missions to cis-lunar space or Mars.
Developing the Building Blocks For Exploration
Overall, the Asteroid Redirect Mission combines the best of NASA’s technology and human exploration efforts. ARM is a compelling early use of the Orion spacecraft and SLS rocket that also affordably lays more foundation for future missions to Mars. The mission will lower the costs of exploration by building systems that can be used and upgraded multiple times. Ultimately, the mission allows NASA to move as fast as possible on a human path to Mars, while minimizing new developments, building experiences aboard the space station, and testing new systems and capabilities in the proving ground of cis-lunar space.
Posted by: Soderman/SSERVI Staff