Thursday, June 30, 2016

Colonize Mars - part 1, a really big rocket (updated 12 July with corrections)

 I had a burning vision of a spacecraft in my head that simply demanded to be written down. In a rush I threw together a bulky, dense post that isn't terribly useful for me so it must be opaque and meandering for anyone else reading. This is not the direction I want to go.

 The solution is to break the whole project into smaller pieces, go deeper into the details, show my work and hopefully try to put some graphics together. We'll see how well it goes.

{{I made a pretty serious mistake in the initial version of this post, one that led to inflated payload capacity. This has since been corrected throughout; I've also removed some commentary that is no longer supported by the numbers.}}

 The first thing you need for a giant transit habitat is a giant rocket. I want a single module to be big enough for Mars gravity at no more than 4 rpm, which works out to 43 meters in diameter. That means a massively large rocket is needed to loft this module in one piece.

 Working on rumor, innuendo, published interviews and Wikipedia it is clear that Elon Musk plans to build such a giant rocket. Nobody knows what the exact size will be, but 12 and 15 meters have been mentioned.

Let's make a bunch of wild assumptions after the jump.

{{Warringer pointed out a web tool for evaluating launcher payloads in the comments; worth a look.}}

If you don't care about the process, the results of those assumptions are LEO payloads of 620 tons for the 12-meter rocket and 1,200 tons for the 15-meter rocket.

Sunday, June 26, 2016

What might Musk's MCT look like?

Here is an entirely speculative look at Elon Musk's proposed Mars Colonial Transporter.
There are no details available, so I'll simply be proposing some options for a vehicle that can carry 100+ people to Mars. I will be making plenty of assumptions and treating this like an entry in a high-level design challenge.

For background, Musk's stated goal is to build a colony on Mars that will reach one million people b̶y̶ ̶2̶1̶0̶0̶ at some point, probably 3000.The point of SpaceX is to be a testbed and funding mechanism for this colonization effort. As unlikely as this sounds, I don't see any reason why it can't be accomplished given sufficient cash.

Details after the break.
(This post was updated with a better estimate of booster size and payload)
((I'm not satisfied with the content; this post is a giant blob without enough detail. I plan to break this into several posts with a deeper look and more visibility into how I arrive at these numbers. Thanks for your patience.))

Monday, June 13, 2016

Microwave sintering - what's the big deal?

It's hard to get through a post or paper on lunar exploration these days without hearing about microwave sintering. Let's take a look at what it is and why so many people are excited about it.

In short, the unique properties of lunar soil make microwave heating very efficient. Strong concrete-like ceramic blocks can be made without water or other materials, just regolith. No material needs means very low mass shipped to the surface for building structures. This takes either a lot of power or a lot of patience.

Details after the break.