Author Archives: Chris Stelter

Airbreathing hypersonic travel is less energy efficient over long distances than rocket travel

There’s a certain misunderstanding common in aerospace that rockets are horribly inefficient and that long term we need air breathing ramjets or scramjets to efficiently launch things, with the idea that we can thus avoid accelerating oxygen to flight speed, … Continue reading

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Plan D for space settlement

Plan D There are three companies I take seriously for making true spacefaring (ie including Mars because I’m a Mars Firster) truly accessible: SpaceX, Blue Origin, And Masten Space Systems. I would have taken XCOR seriously, but unfortunately they went … Continue reading

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Megacharger costs… (Tesla Semi Part Two)

Elon Musk announced the Tesla Semi months ago, now. Besides the low cost, one of the things people are most incredulous about are the Megacharger costs. Tesla announced just 7 cents per kWh, flat price, to charge at a Megacharger. … Continue reading

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Tesla Semi is reasonable, part 1

Tesla finally unveiled their semi truck: tesla.com/semi/ An electric monster with 4 Model 3 motors, one for each drive wheel, with an astounding 500 mile range (beating most people’s expectations). Fully loaded (i.e. 80,000 lbs total), it can accelerate from … Continue reading

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Space-based Bitcoin Mining

Preface: if you’re a bitcoin expert, gird your loins because I’m probably going to be making a LOT of technical errors in this post. So: space based solar power, but instead of beaming the power to Earth, we mine bitcoin … Continue reading

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Energy needed to get to orbit using various fuels from various planets.

EDIT: I made a big mistake on how I calculate bulk density. I’ll fix it. EDIT AGAIN: I fixed it. I think. I will pick stoichiometric mixes, oxygen as oxidizer and fuels of hydrogen, methane, and carbon monoxide. The three … Continue reading

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Working full time on the Martian surface is within US Radiation Worker limits

The US Radiation Worker annual radiation limit is 5 rem, or 50mSv/year. Divided into the 2000 annual working hours, that’s 0.025mSv/hour. The Mars Curiosity rover measured an average dosage on Mars of 0.67mSv/day at about -4km altitude. That’s 0.028mSv/hour. If … Continue reading

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Homo Cosmicus: Vestibular Implants

EDIT: David Birchler mentioned in the comments that an implant is not required. The technology is called galvanic vestibular stimulation and it can stimulate the sensation of pitch, roll, and yaw. Since surgery is not required, it sounds like this … Continue reading

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Perfectly energy-efficient rocket vehicle

So I was watching a video of a talk by Geoffrey Landis (my old mentor when I was an intern at Glenn), and he made a very interesting point. If you’re trying to maximize energy efficiency for a rocket and … Continue reading

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Reusable Falcon Heavy payload (upper stage staging velocity)

Jon and I were discussing the recent Falcon Heavy payload numbers. Expendable performance to GTO is supposed to be 22 tons (metric, same for the rest of this post). Given how aggressive that is, and given the history of Falcon … Continue reading

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