Selenian Boondocks

While attending the Responsive Space Conference in Los Angeles, I had an opportunity along with many others to visit the SpaceX facility in Hawthorne on the evening of March 9th and I had a wonderful time.
We were given a brief tour of the facility by Brian Bjelde, who began by showing us a full-scale mockup [...]

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guest blogger john hare
I had an interesting conversation with Jon last month about the problems with air launching rocket ships. The various flavors of air launch involve some form of altitude and velocity loss as the rocket ship drops away from the mother ship before it can light it’s engines. In most cases, it also [...]

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“Program manager John Shannon said Tuesday it costs $200 million a month to keep the fleet flying.”
This is why President Bush and Sean O’Keefe knew that we would have to bring the shuttle program to an end in order to have any hope of going forward with NASA’s use of space. Michael Griffin knew [...]

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From NASA administrator Charlie Bolden:
“I find great comfort in knowing that President Obama has seen fit to put his faith in us to develop a game-changing strategy in our four mission areas, and that he has given us a $6 billion plus up on our FY10 budget as a show of support and trust. I [...]

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This is my last update to the payload fraction calculation, I promise.
When I was learning how to use mass-estimating relationships (MERs) at Georgia Tech, our focus was on reusable launch vehicles, and most of our MERs came from NASA Langley, where my professor had once worked. When it came to much of the reusability [...]

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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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