As I was writing the previous Lagrange post, a thought occurred: what about skyhooks, and, more specifically, space elevators?

“[Space elevators will be taken seriously] Probably about 50 years after everybody quits laughing.”
Arthur C. Clarke

He’s right you know. The idea is still ridiculous, even with the amazingly light-weight materials in development. The “rope” that would tether an object would be way too heavy still - not to mention wildlife and wind, and all sorts of crap you have to deal with. But that’s for Earth. Instead of building one here, why not the Moon?

All those problems go away. Instead, you introduce all new ones! Two very important questions arise though.

• How do you get the needed materials, equipment, and man-power to the moon?
• What problem does it solve? What does it allow you to do that weren’t able to before?

Honestly, I have no reasonable answer at this point, but it would be cool, wouldn’t it? Of course, you can just launch all your stuff to the moon and do it all on-site, but that’s a direct lead in to the next, and I think, more important question. “Because it’s there” in this case isn’t good enough. The only way a space-elevator would be viable is if there’s already a presence on the body the elevator from which it is being constructed.

This all ties into Lagrangian Points though because a “conventional” space elevator uses a counterweight in geosynchronous (or lunar-synchronous, or whatever) orbit. I haven’t thought it through, but are there any advantages to be had by anchoring to something in a Lagrangian Point?

Comma, comma, comma, comma, comma, chameleon.

First, I’ll let you get up to speed here, as well a short summary. A Lagrangian Point is a point where you can be between the Earth and the Moon and not have the pull of either body’s gravity take you to them. There are a handful of them in the Earth-Moon System, and they are not unique to Earth either. Anywhere there are orbiting bodies, there are these gravitational “back-eddies.” These Lagrangian points are cool because you can just sit there and be pulled along with the Earth and Moon and not have to worry about falling to either of them. They each pull you an equal amount and you just float.

A Lagrangian Point is an ideal location for a micro-gravity semi-stationary space platform of significant size. On this platform, you could have a factory churning out space-ships and launching them from there. If you could take advantage of a zero escape velocity, think of all the cool stuff we could put in a spacecraft not mostly dedicated simply to getting to space, and focus on the stuff for being in space.

Getting into outer space from Earth is no small feat because you have to push so very hard. Most of the volume of a spacecraft launched from Earth is devoted to getting to orbit and beyond.

There’s a major problem with all of this though - there always is, isn’t there? I don’t see this discussed whenever I happen upon Lagrangian Points out there on the Intertubes, but what happens when the mass of whatever placed in the Lagrangian Point is no longer neglibile? It changes the system. The Lagrangian Point for a two-body system will move. Intuitively, to save energy, you would simply move the space-station to the new point. Doing so would move the point further, and continuing to move would be like chasing your own tail. The more prudent solution would be to maintain the relative position between the two bodies and hope for the best.

Then again, a non-negligible mass is nothing small. To be considered significant, the mass of such an object would be so large, that technology may have advanced enough to build a structure of such a size that we could live on it and move to wherever we wanted. Planets be damned!

“‘Once the rockets are up, who cares where they come down?
That’s not my department,’ says Wernher von Braun”
Tom Lehrer 

*It turns out I just had to read further, and I’m not the only one to think of the problem of stability. Honestly, I’m not surprised - far more and smarter people than me are astronomers and physicists, and this is their bread and butter. Small observational platforms already exist in specialized orbits around other Lagrangian Points

I’ve managed to survive another solar rotation. I demand you celebrate my amazing accomplishment of staying alive! I don’t gotta do nuthin’ today… except take a physics test. Bah.

“My name is Ozymandias, king of kings:
Look on my works, ye Mighty, and despair!”

A coworker pointed me to this link today: news.co.au.

The long and short of this is a rediscovery that separating Scotch tape at the right speed, X-Rays are emitted at a powerful enough voltage to take images. The Soviets in the 1950s documented this research, but with a lot of things the Soviets did, it was lost to time. Remember internal combustion run-assist robot legs? No? It worked, but it had a tendency to wear knee-caps out much faster than normal.

The Russians applied research division was spectacular. I don’t have any hard numbers in front of me, but I imagine it was a lot like DARPA with a shoestring budget. Basically, a bunch of brilliant Russian MacGyvers went to the junkyard every day to see what they could come up with. Because they were all geniuses (geniii?), they came up with Scotch tape X-Rays, flying saucers (yes), and disturbing dog heads.

It’s becoming increasingly difficult because they’re all dying off, but put a Soviet scientist on a team and you will come up with some really cool and hacked together tech. Remember Junkyard Wars on Discovery Channel? The Russian team made the ricketiest shit, but it almost always worked better than the other teams’ contraptions. My favorite part of the Russian team is they had old C.C.C.P. patches and logos on their clothes. Hard. Core. What seems to make the Russians great is they tend to engineer only what is necessary and nothing more.

The odd thing about what they build, is it can take a beating, have non-trivial bits fall off and still be functional. Look at the Mir space station for example. This hunk of junk surprised us Westerners at almost every turn. This ramshackle beast of an orbiter stayed up for 15 years (original launch in 1986, fully assembled 1996, and de-orbited 2001).

MESSENGER is a scientific investigation – by spacecraft – of the planet Mercury. The name comes from “MErcury Surface, Space ENvironment, Geochemistry, and Ranging,” highlighting the project’s broad range of scientific goals.

MESSENGER is the first orbital study of Mercury, and this is very cool! I’m all for the exploration of space at any cost. What makes me most interested in this mission is not that it’s the first mission of its type to Mercury, but the way the probe is arriving. I’ve swiped the image from the Mission Page, so I can show it to you here:

The MESSENGER probe follows quite a circuitous path to its destination (click for big)

What you see here, is a diagram of the trajectory the probe will take.

1. The probe leaves Earth
2. One year later, Earth gives it a gravity-assisted push to Venus
3. Venus catches it and pushes it out again on a slightly different orbital path
4. Venus catches it again and pushes it to Mercury
5. Mercury then catches and pushes it three times, each time placing it on a slightly different path
6. The fourth time the probe encounters Mercury, the probe is supposed to be at the right speed and vector to enter orbit

That’s pretty nuts, huh? Seeing this trajectory diagram gives me a great excuse to show you my wallpaper at work.

Crippled satellite slingshots around moon to correct its orbit (click for original article)

Basically, a satellite got fucked and we needed to get it back - but how? SEND IT TO THE MOON! The science behind this is obvsiouly rocket science, but it’s really not that hard. For the most part, if you had the idea to use gravity wells in sequence to get the proper vectors in order, a low-level physicist, even a B student at a community college, could bang this out in an afternoon. Of course there are other like effeciency and mass changes due to using fuel for launch and attitude controls, but the “big picture” really is as easy as solving for x.

nanos gigantum humeris insidentes

It’s hard to think of a more applicable quote than “Standing on the shoulders of giants…” here. If a relatively uneducated person (relative to a top physicist), can come up with an trajectory of a probe that uses planets as gravity-assist slingshots for proper orbital insertion, then humanity has come a long way since believing “Here be dragons.”

Of what use is a child? 
-Benjamin Franklin

That depends - what is its tensile strength?

PS: In this post, I go crazy with HTML tags.