NASA is exploring a shift toward the development of technologies for In-Situ Resource Utilization (ISRU) – a development that could allow crews to make use of natural resources at their mission destinations – with a focus on crewed missions to Mars – instead of taking all needed supplies with them from Earth.
Taking it all with you:
The delicate balance between what and how much equipment and supplies to launch with a space mission has always been a chief concern in spaceflight operations and mission planning.
In spaceflight, there is always a need to balance the amount of supplies packed onto the spacecraft versus how much the spacecraft’s boosters and engines can actually deliver to the intended destination.
Toward the end of the Space Shuttle Program (SSP), this delicate balance also saw the added factor of needing to put as much equipment onto the vehicle for missions to the International Space Station (ISS) and Hubble Space Telescope (HST) as possible before the completion of the program’s lifetime.
Thus, a vast majority of the final Space Shuttle missions launched at or very near their maximum up-mass capability in terms of supplies and mission needs.
But this up-mass concern was not always limited to supplies.
During the multi-month delay to the STS-117 Atlantis mission in 2007, the need for that mission to take on the role of crew rotation flight for the ISS caused some concern as the mission’s payload was already near the up-mass limit for Atlantis – a limit that originally restricted the crew size to six instead of seven.
For the STS-117 mission, the fact that the multi-month delay pushed the flight’s launch out of the winter months and into the summer months created more up-mass capability – as the Shuttle as a launch system performed more efficiently in summer months than in winter months.
This largely solved the up-mass issue for STS-117, and the addition of the seventh crewmember became less of a concern – though payload and supply weight was still carefully monitored in the weeks leading up to the launch of the mission.
Likewise, when Atlantis’s much-anticipated STS-125 mission to the Hubble Space Telescope was delayed in the final weeks of pad processing due to a problem on Hubble, the fix seemed simple at first: Put a replacement part for the one that malfunction on Hubble on Atlantis and launch the mission at a later date.
However, Atlantis was once again near her maximum up-mass capability, and adding an additional component, while doable, put the mission near its maximum up-mass limit.
Since the STS-119 SRBs were cast for a winter launch, their power was slightly enhanced to counter the decreased performance of the Shuttle during a winter launch.
Thus, the increased power would now be with Atlantis on a Summer-time launch to Hubble – adding launch performance and up-mass capability.
But it was not just these two Shuttle missions that experienced the difficulty of having to balance the needs of the mission with taking everything needed with the crew from the moment of launch.
Every space mission, be it the other 133 Shuttle missions, the Apollo lunar missions, unmanned satellite launches, etc. must take everything necessary for the mission with it at launch.
ISS – waste water reclamation and 3-D printing:
While physical supplies certainly needed to be launched with a mission, there have been, for several decades, certain items that could be produced on orbit instead.
During a Space Shuttle mission, most of the crew’s drinking water came as a byproduct of the combustion of hydrogen and oxygen for the vehicle’s fuel cells.
In this case, only the hydrogen and oxygen had to be carried with the mission from launch. The water was produced from those chemical components, during the process to create electricity for the Orbiter, on orbit.
Likewise, for many years now, crews aboard the ISS have been able to use the wastewater reclamation system (which turns wastewater into purified potable water) to reduce the amount of water launched from Earth on ISS resupply missions.
Moreover, NASA has made use of increasing technological capabilities to provide more efficient service to ISS needs.
Most notably was when an equipment failure on ISS necessitated the need for a wrench as part of the repairs.
Not having the needed wrench on board the Space Station would normally have meant waiting to repair the piece of equipment until the next resupply mission could be launched to deliver the wrench from the ground.
But the Space Station’s 3-D printer provided another option. NASA could simply email the specifications for printing the wrench to the Station’s crew and they could then print the wrench and use it to repair the piece of equipment.
Which is exactly what happened.
In this manner, while all of the ingredients needed to produce the wrench had already been launched to the ISS, NASA could use those resources already present in the most efficient way possible.
Using the resources that are there:
To allow for this, NASA has begun developing the resources and capabilities here on Earth needed to facilitate such in-situ utilization of resources.
The process, called In-Situ Resource Utilization (ISRU), is the “harvesting and reliance on available raw materials as astronauts visit deep-space destinations.”
According to Josephine Burnett, director of the Kennedy Space Center’s Exploration Research and Technology Programs organization, “These new technological capabilities will enable NASA to become less dependent on Earth-based logistics and instead use local resources to maintain a sustained human presence in space.”
This type of ISRU could have significant effects on the amount of resources launched with the mission.
In fact, the simple use of already present resources could “reduce the weight of an outfitted exploration spacecraft by 40 percent,” stated Jack Fox, chief of the Science and Technology Projects Division of the Exploration Research and Technology Programs Directorate at the Kennedy Space Center.
“We believe learning to live off available resources will significantly reduce the mass, cost and risk of near and long-term space exploration.”
Chief among these available resources is water.
In recent years, numerous planetary survey missions have returned impressive results showing the abundance of water throughout the solar system.
In particular, new estimates for the amount of water contained under the lunar regolith and in the permanently shadowed craters at the lunar poles indicate the presence of more than enough water to sustain a human lunar colony.
But this sustainability isn’t just because of the necessity of water for life.
It also extends from the constituent components of water – hydrogen and oxygen – that can be used as source of power (as it was for Shuttle).
Additionally, the hydrogen and oxygen could also be used as propellant, thereby making the moon a potential “gas station” in space.
But before any of that can happen, a greater understanding of the concentration of water and other lunar resources is needed.
Thus, the Science and Technology Projects Division of the Exploration Research and Technology Programs team at the Kennedy Space Center is developing the Regolith and Environment Science and Oxygen and Lunar Volatiles Extraction (RESOLVE) experiment, designed to be part of NASA’s lunar Resource Prospector mission in 2020.
This Resource Prospector mission will create a more accurate understanding of the quantity and types of lunar resources astronauts might be able to use on site at a lunar colony.
But it isn’t just water that holds the potential for ISRU.
The moon’s regolith is also a prime contender due in part to its volcanic basalt composition.
As Fox notes, “Construction materials containing basalt and a bonding agent would be two to three times stronger in compression than normal cement concrete used on Earth.”
The types of construction that could be possible on the moon (and even Mars) with regolith include launch and landing pads, equipment sheds, regolith mining for oxygen, and water ice mining.
However, using the resources that are already present is only part of the equation for permanent human habitation in space.
Learning how to grow food in a microgravity or non-Earth gravity environment is another large step for both long-term habitation of other worlds and deep space, long-duration missions.
Experiments currently being conducted aboard the International Space Station and at the Kennedy Space Center in Florida are examining the ways that environmental and life-support systems work in combination with the need to grow food from plants – which absorb carbon dioxide and produce breathable oxygen.
Living on Mars:
While this idea for ISRU aboard the ISS and on the lunar surface is promising and necessary, those two destinations still provide short-term access to Earth. If something goes wrong and a new piece of equipment or resource is needed, it can be brought up on a future resupply mission.
Missions to Mars do not have that luxury, and learning to use the resources Mars has to a potential human mission’s advantage will be crucial in actually executing a successful human mission to the red planet.
Thus, NASA plans to use its upcoming 2020 Mars rover mission to capitalize on the success of the ongoing Curiosity mission and explore in more depth ISRU potentials on the red planet.
To this end, the goals of the 2020 Mars rover mission will include the characterization of the ancient Martian environment, the identification of samples for future sample return missions, and the test extraction of oxygen from Mars’s carbon dioxide rich atmosphere.
This last goal will be aided in large part by the Mars Oxygen ISRU Experiment (MOXIE).
MOXIE will test solid oxide electrolysis technology on a scale that, if successful, could be expanded to meet human mission requirements.
Moreover, NASA and space industry experts have identified Mars and one of its moons, Phobos, as holding potential for natural utilization of water ice and chemical resources in support of human exploration.
“We know there are solvable challenges for human missions to Mars,” Fox said.
“We have multiple programs in progress that will allow us to overcome the unknowns and make the best use of what we need to take along and what we’ll find when we get there.”
(Images via NASA, Orbital ATK and L2 Historical).
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