Tom Markusic, of Space Exploration Technologies (SpaceX), recently warned that spaceflight on its present course “will devolve into social welfare for nerds.” To escape federally funded self-indulgence, Markusic proposes developing a potentially game-changing technology: nuclear thermal propulsion. But its nominal prospects only make his unhappy prediction for the future of spaceflight more likely.
NASA chief Charles Bolden called for new ideas after President Obama earlier this year cancelled the Constellation project, which looked much like its antecedent, the half-century old Apollo program. Nuclear thermal propulsion, which Markusic advocates for getting to Mars, also dates back to the golden age of space. Beginning in the 1950s and continuing into the ‘60s, NASA extensively investigated thermal nuclear technology which combusts hydrogen at the extreme temperatures of a nuclear reactor, providing much greater thrust than the chemical reaction used in conventional rockets.
Clearly it’s not a new idea. Rather it underlines the paucity of new, workable technologies that meaningfully enhance the prospects for human exploration of space.
Nuclear thermal does work and it delivers about twice the kick from a given amount of hydrogen compared to burning it the usual way. But it’s expensive. And it’s nuclear. In the 1950s we looked forward to everything atomic. But no longer.
SpaceX founder Elon Musk contradicted Markusic a few days ago saying “I don’t think nuclear thermal is the way to go.” Musk, perhaps wanting to keep his company out of the nuclear fray, said the weight of the reactor would offset the benefit of greater combustion energy. However, Stanley Borowski and colleagues at NASA firmly contend that nuclear thermal rockets would roughly halve the transit time for a Mars mission from about 4.7 years to 2.5. But a not-quite-factor-of-two improvement has failed to captivate.
When Musk entered the rocket business, he was looking for a “Moore’s law of space,” exponential advances which would make humanity a spacefaring species. Markusic appears to have truer insight into the future of spaceflight.
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