The electric ion engine that currently propels the Dawn mission has a nominal operation power of 2.3 kW, and the new Boeing satellites operate at slightly less than 5 kW. Upgraded engines tested for ARM offer electric propulsion devices that could operate at nearly 15 kW. Aerojet Rocketdyne’s Nested Hall Thruster delivers 50-200 kW and the VASMIR VX-200 engine has performed more than 10,000 test firings at power levels of 200 kW.
But none of these engines have yet flown to space.
Cassady put things in perspective. “Today we can land one metric ton on the surface of Mars; for a human mission we need to land 80 metric tons of supplies and equipment,” he said. “Mars missions will also send humans much farther than ever before. This combination of heavier payloads combined with the need to travel over greater distances drives us to seek a solution that takes advantage of strategic logistics planning.”
He added that the best approach might be similar to the way that military deployments are conducted today, where heavy equipment, supplies, and other logistical items are pre-deployed by large cargo ships. Then, once the equipment and habitats are in place, soldiers follow by faster air transport. SEP systems, in other words, could become the cargo ship of deep-space missions.
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Gerstenmaier said that NASA is also investing in technologies that will allow for the in-space storage and transfer of cryogenic fuels to meet the needs for future propulsion stages to move crew from Low Earth Orbit to a variety of destinations. “A key goal is to demonstrate these new capabilities in the next few years and infuse them into human missions in the next decade,” he said.
Several committee members and invited speakers echoed Chang-Diaz’s opinion that there is strong public sentiment for continued development for space exploration, and in particular a sustainable human mission to Mars.
“I believe space travel beckons humanity even more today than it did 50 years ago,” said Chang Diaz, “but we need to secure a safe, robust, and fast means of transportation.”
Cassady agreed, saying he thought that we are well on our way to having efficient in-space transportation because of SEP, but for the technology to fully reach its potential, we mustn’t get complacent or distracted.
“We must continue to adequately fund these development efforts to ensure we will have the first human footprints on Mars in the 2030s,” he said. “The primary challenge facing high power SEP development is the risk of losing focus as we go through the critical transition period from development to flight demonstration and subsequently, operational use. This requires a stable budget and a constancy of purpose. Everything we do should be with the goal of landing humans on Mars in the 2030s.”
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