Space Architecture

Sunday, December 17, 2006

Mars Gravity Biosatellite

As a follow-up to the previous post about artificial gravity, here's a group, called Mars Gravity, that plans to launch a satellite that will simulate Martian gravity for 15 mice. According to this Press Release, "the mission could launch in 2006". Well, the year 2006 ends in a few weeks. According the program's sponsor website, Your Name Into Space, the satellite won't launch until 2010.

Better later than never (just say that to yourself repeatedly).

How will the artificial gravity be created? I'm not sure, judging by reading the website. I think that the spinning itself would be created by the Guidance, Navigation, and Control (GN&C) System and/or the Attitude Determination and Control (ADC) System. According to the1988 Shuttle Reference Manual, the Rotational Hand Controller (RHC) controls the vehicle's rotation on the three axes: yaw, pitch, and roll. I presume that the satellite-equivalent of the RHC would maintain a constant rotation about one axis, while maintaining relative stability about the other two.

Friday, December 15, 2006

"Artificial Gravity and the Architecture of Orbital Habitats" by Theodore Hall

Found this on Space Future, which is the site for "everyone who wants to go into space". It has a repository of articles, such as the one title for this blog entry. I found it while googling "space pyschology".

The article focuses on artificial gravity, with the intent of it being a mitigation strategy for people who live in otherwise microgravity environments for long periods of time. It's a very long piece, worth about 20 presses of the Page Down key on your keyboard. Hall lists 19 effects of living in microgravity, all of which is enough to discourage anyone from living in space. He goes into the formulas that one may use to determine an optimal angular velocity. One wants fast enough to have strong gravity, but not so fast as to induce disorientation every time the astronaut turns his/her head. Which means that one wants a very long radius. The longer, the better.

He writes at the end,
The design of an orbital habitat for artificial gravity depends on much more than physics. A few simple formulae relate the habitat's size and rotation to the apparent gravity. Unfortunately, the formulae are powerless to predict the satisfaction of the inhabitants. Many empirical studies have attempted to identify the comfort boundaries for artificial gravity, to constrain the values of the variables. Nevertheless, they have arrived at substantially different conclusions. The disagreement may be due in part to different assumptions regarding the mission, selection, motivation and adaptability of the target population. To support a large clientele, it may be safe to stay within the common ground of all of the empirical studies, choosing the most restrictive bounding value for each variable.

So much for clear answers. But, how to induce rotation in the first place, and keep it going? Hall doesn't go into that.

Thursday, December 14, 2006

Fa la la la

Hope you are having a good holiday season thus far. Here's the low-down.

Just finished my final presentaton on my Emergency Operations Center. Here's an image from the presentation:

In other news, the FAA has a good FAQ on "Commercial Space Topics". Here are some quotes:

Why isn't NASA, as the U.S. space agency, responsible for the safety and success of commercial space transportation?

NASA is a research and development agency of the federal government, and as such neither operates nor regulates the commercial space transportation industry. The regulatory responsibility for the industry falls to the Federal Aviation Administration, which is a regulatory agency. NASA does, however, often use launch satellites and spacecraft on vehicles developed by private companies.

What does a commercial space launch cost a launch customer?

Launch prices depend on the vehicle being used for the launch, which is determined by the size and destination of the payload being launched. Generally, the larger the payload, the larger the vehicle required, and thus the greater the price. Commercial launches are priced at as little as $8 million for a flight on the Russian START launch vehicle and as much as $180 million for a European Ariane 5 rocket.

So, what are some options?

Russian START launch vehicle: 400 kg payload to LEO. Cost: $8m

Ariane 5 rocket: 17,500 kg payload to LEO. Cost: $180m.

Space Shuttle: 21,000 kg - 24,900 kg to LEO. Cost: $450m.

The payload figures come from The Encyclopedia of Astrobiology, Astronomy, and Spaceflight. Costs came from the FAA for the Russian START and Ariane 5. Costs for the Shuttle come from NASA.

Crunching some numbers, the most cost effective of these are the Ariane 5, costing $10,285/kg, followed by the Shuttle, for at least $18,000/kg, and finally Russian START, costing a Shuttle-like $20,000/kg to launch 400 kg.