Selenian Boondocks

Continuing with our story from last time…
The next day, your boss pokes his head in your office and asks:
“How’s those forty trans-Mars injection stages going?”
He notices that you’re checking out scuba-dive sites in the Caribbean for your upcoming vacation with your feet up on the desk, and comes into the room with the blood rising [...]

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Now that I’ve gotten the math and derivations out of the way, let’s us the payload fraction expressions in a real-world example.

Let’s say you work for the chief technologist of NASA, and he’s thinking about sending humans to Mars. He’s considering whether or not to invest in a seemingly-promising new technology: nuclear thermal propulsion. [...]

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In the last post, I attempted to calculate a basic expression for the propellant-mass-sensitive term (lambda) and in this one I will attempt to do the same thing for the gross-mass-sensitive term (phi). In so doing, I will hopefully be able to show how a number of key factors in the rocket design affect [...]

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In my last two posts I’ve been talking about calculating payload fraction of a rocket using the mass ratio from the rocket equation and some vehicle parameters that have been sensitive to propellant mass and gross mass. To use these parameters successfully, it would be helpful to have some idea what they should be [...]

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As I prepared for this post tonight, I realized that I wasn’t really modifying the rocket equation at all–I have been using the rocket equation and a summation of mass terms to find the payload fraction, which I consider an especially useful value to know.
Furthermore, if you read my previous post, you probably figured out [...]

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When I was an undergrad, I spent two summers interning on the X-33 program at the Lockheed Martin Skunk Works in Palmdale, California. It was a fantastic experience and I got to meet with and work with some wonderful people on a very exciting program. Plus I got to live in the Mojave [...]

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guest blogger john hare
Anytime a mission, manned or robotic, is proposed to destinations beyond Mars, travel times of years to decades are involved. Efforts to reduce trip times depend on some propulsion system well beyond the capabilities of chemical propulsion. The problem with most proposed systems is either the Isp is still not good enough, [...]

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guest blogger john hare
We have another year of hope ahead of us, let us do what we can to fulfill that hope and further our dreams for a prosperous new year.
For a very long time many of us said that our new years resolution was to be less skilled at crisis management through less practice. [...]

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guest blogger john hare
A variant on the compound tether is the electrodynamic tether with rotovator. In this one a long electrodynamic tether has solar panels and other counterweights high enough to get the center of mass to a 135 minute  orbit with the bottom end at LEO altitudes. With the bottom end at 2,500 m/s below local [...]

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guest blogger john hare
Ramjets come up just about every time someone takes a fresh look at space launch. It seems such an obvious approach that very few of us have skipped looking into them. The trade studies that have been done repeatedly show that there is no benefit to their use in acceleration missions, which [...]

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