Space! The Final Frontier! Why do we care?
by Mad Rocket Scientist
The genesis of this post is from KatherineMW, who wrote:
And we couldn’t do the same or better by devoting our research directly to practical applications, instead of having some useful applications as a spin-off effect from vanity megaprojects?
This is a common feeling many have, and while understandable, the efforts of NASA, et. al. were not just about political and patriotic vanity. There was a lot of real science and engineering happening there, science that has impacted us all far beyond the reach of Velcro and Tang (neither of which was invented by NASA, only popularized by it). So as part of the Ordinary University, I’d like to talk about some of the technologies of space travel, and the difference those technologies make to us all. I also want to talk about the potential a space elevator has for us all. I also welcome in the comments any other technologies and advancements that can be attributed to the vanity megaprojects that I will have missed.
Getting into space – Rockets, AKA The Bomb You Ride:
Stand up where you are and point your arm straight up. Space is about 60 miles that-a-way. It’s not far at all, considering the other side of the Earth is more than 130 times that far away. Earth has a remarkably thin layer of air all about it, but escaping that layer is a trick. I mean, we’ve all seen rockets and the shuttle launch, it’s spectacular, and violent, and they talk all about traveling at very high Mach numbers, etc. But the launch of a commercial airliner is nothing major, and it’s going up 7 to 8 miles without a problem. Even the SR-71 spy plane could get up to about 20 miles and fly around up there, and we were doing that back in the early 60’s.
So why is that extra 40 miles such a bear? Is it just because the air is so thin wings don’t work? But less air means less air resistance! It can’t be because of gravity, because that gets weaker as you climb, right? So it should get easier!
The thing is, if it was just about getting high enough, it really would be a simple problem. But it’s not, it’s all about going fast enough. We’ve all heard the term “Escape Velocity”, but what is it really? The common misconception is that it is the speed at which we have to be climbing in order to break away from the Earth, and if you don’t reach that velocity fast enough, you’ll fall back to Earth. That’s wrong, plain and simple. Give me enough fuel, and I can leave the Earth in a rocket going 10 miles an hour. What I won’t be able to do is achieve orbit, and orbit is where we get all the work done. For the Earth, the escape velocity is 11.2 km/s (about 25,000 mph). That means that your ship has to be traveling that fast around the Earth, not away from it. When you reach that speed at the correct altitude, what is happening is that the energy of your motion is balanced with the force of gravity. The easiest way to think of this is if you were to put a weight on the end of an elastic string and spin it in a circle. The string is the force of gravity and the movement of the weight is like a space ship in flight. The faster you spin, the more the elastic stretches; the slower the spin, the more the elastic contracts.
So when we launch a rocket, we aren’t burning all that fuel to climb, we are burning the majority of it to achieve orbital velocity. And even when you eliminate air resistance, you still need a lot of energy to accelerate a mass to escape velocity. Which means a lot of fuel, which means a lot of rocket to hold that fuel (even when using stages to shed unnecessary mass). And since the fuel has to have a lot of energy, and it has to have its own oxidizer, it is fairly unstable and a beast to work with. Which in turn requires a lot of expensive, hard to build machinery that will very likely be destroyed in the process of using it. Thus the cost of lifting 1 kg of cargo to orbit is on the order of hundreds to thousands of dollars per kg. And that completely ignores the possibility of the bomb it’s riding on doing the whole bomb thing, instead of delivering the payload safely.
Unfortunately, right now that is the only game in town. And getting home has its own set of problems, what with re-entry being very tricky, and surviving the heating during aero-braking, and then getting safely on the ground.
Space – Lovely Views, But Don’t Open The Windows!
So, you’ve made it to space, now what? Well, some things to keep in mind in that space is a hostile environment for us fleshy things. We evolved in a gravity well, under 14.7 psi of pressure, at about 70 degrees F. That is where we thrive. Space, on the other hand, has little gravity to speak of, no real pressure to work with, and only two temperatures that can best be described as “Worst Sunburn Ever!” and “Suddenly Antarctica Seems Pleasant”. Then there is the other radiation permeating space that can cook you like a sausage in a microwave. All of which means that living space must be air tight, pressurized, shielded, and heavily climate controlled, and since we actually need gravity or our bodies start to suffer bad things, we can’t stay too long up there. Toss in the ever present threat of objects too small to detect moving 10+ times faster than a bullet that can intersect your living space rather violently and, well, Family Vacation spot it isn’t.
Space – Umm, Why?
So it’s expensive and dangerous to get there, and expensive and dangerous to live there, and dangerous to get back, so aside from tossing up some satellites, why do we even bother putting people up there? Well, aside from the vanity and adventure aspects, space offers us a lot of exciting possibilities, from vastly expanded living space, to vastly expanded resources, to unique manufacturing possibilities. Also, having a person in space does make it easier to solve problems and conduct experiments. It also allows us to research the effects of space and micro-gravity on human bodies However, right now those are really the only reasons to put people in orbit (as much as the wanna-be astronaut in me is sobbing in disbelief that I said that). But that will not be the case forever. We will find better ways into space, and better ways to live there, and putting people in space is a big part of how we get there.
But what have we gotten out of it all so far?
There are, of course, all the cool videos and photos. There is also the vast expansion of our knowledge of astronomy and astrophysics (Hubble, SOHO, etc.). But what about the more mundane?
Well, I could compile a list, but I’ll be lazy and just link this Wikipedia list. It is not an exhaustive list by a long shot, but it is a good place to start. I’m sure some of those technologies would have come about anyway (artificial limbs, anti-icing systems, etc.), but the space program pushed them along a lot faster, so we gained the benefits of them much sooner than we would have otherwise.
For a more exhaustive list of technologies that were born or accelerated by the space program, see Spinoff.
Going Up Easy
There are really two ways to make getting into space safer. One is to develop some kind of reactionless drive, and the other is a space elevator. We could, of course, dither around with launching rockets from airplanes, or giant mountainside rail guns, etc., but in the end it’s still a rocket. While there are some interesting theoretical reactionless drives, currently none are anything more than neat thought experiments and some equations. A space elevator, on the other hand, is quite literally something I may very well see in my lifetime (and I am 40 this summer). We have a material that can do it, we know how to do it, and while it would be expensive, the benefits would enormously outweigh the upfront costs.
Talk To Me About That 10 MPH Ride Into Space
So how would we go about building a Space Elevator?
The first hurdle is the cable. Carbon Nanotubes can be assembled into a ribbon-like material that has a phenomenal strength (on the order of 50 times stronger than the toughest steel). We are still working out the kinks in how to produce the stuff in large quantities, but that is something we’ll have solved very, very soon.
Once we have the ribbon, the next step is the tricky part. We need a base. The base has to be on or very close to the equator (i.e. within 20 degrees of Latitude, but the closer the better). If you look at a map, you’ll notice that there isn’t exactly a lot of land along the equator. Right now, Brazil probably represents the most stable polity in which such a base could be located. Otherwise, it would have to be on one of the many islands along the equator. To be honest, Brazil would probably be a good choice, as the economic benefits it would bring to that part of the world would be hard to imagine (although I’d worry such a thing would also hasten the clearing of the Amazon; as well as Brazil not being known for the political class taking good care of the under-class, so the potential economic benefits would be poorly distributed if nothing was changed).
So let’s assume we have a base, out at sea, but near the mouth of the Amazon. The base itself is pretty straightforward. It’s an anchor. Sink your supports deep into the Earth and build the fanciest oil rig you can right there. It doesn’t have to be too strong, just strong enough to keep tension on the cables. Remember, the base isn’t holding the station in orbit, it’s just keeping the cables tight.
Drop Me a Line
Now for the expensive and technically tricky bit, we need to design and build a space station at a geostationary orbit. That is 35,786 kilometers (22,236 mi) above the mouth of the Amazon. This will involve a lot of rockets and astronauts and materials. Such a station will be similar in many ways to the ISS, but also trickier, as it will be much further away. The station itself initially has but one job, to deploy (and possibly manufacture) the longest shot line, ever! Of course, it isn’t deploying just one line, but actually two. This is because of orbital mechanics. In short, the position of your orbit is defined by your center of gravity. If a station at GEOS orbit started paying out a shot line toward the Earth, slowly but surely the center of gravity of the station would shift into lower orbits, causing it to move out of alignment with the target base. However, if it sent out a second shot line in the opposite direction, then the center of gravity would remain stable.
Now the shot line would be just that, a very thin line, as thin as we can manage and still have it survive passing through jet streams and trade winds (it would, of course, have a weight on the end). When it was low enough, we would catch it and guide it in the rest of the way. Once it was locked into place at the base, you start building the cable just like you would a suspension bridge. You send a cable climber up and have it trail more cable behind it. Then you do that again and again and again until you have a cable strong enough to start moving heavier cars and loads. You can lay out additional cables using the main cable in a similar manner, so in the end you could have a main center cable and an array of additional cables arranged around it (e.g. one main central cable and 6 additional cables around it).
Of course, as the cable is built, so must the counter weight. The center of gravity of the whole system has to remain at GEOS, but the counterweight does not have to be an additional 36000 km away in space, it merely has to be far enough and massive enough to maintain the COG at GEOS. The counterweight could be a captured asteroid, or another space station further out. The counterweight itself would be reeled in and payed out as needed to keep the whole system balanced.
Once the cables are in place and cars are traveling along them, materials and supplies can be sent to the station for a tiny fraction of the cost of a rocket, and on much shorter notice. The whole affair is self-powered. Carbon nanotubes are electrically conductive. If you take any electrical conductor and pass it perpendicularly through a magnetic field, you will induce a current in the conductor. The Earth has a mighty big magnetic field and the cable will be perpendicular to all of it. The cable will carry an enormous amount of electricity, more than enough to power the base, the station, and the cars, with plenty to spare.
And, of course, once we have one station up there, it can be used to support the building of other elevators, so we are not limited to just one path up.
Ding! 4054th Floor. Hardware, Ladies Lingerie, Door Way to Space.
The station itself can begin expanding in ways the ISS never can. To date, all our orbital facilities are extremely fragile. This is because of the expense of lifting mass into orbit. So SpaceLab, Mir, and the ISS are delicate containers, just strong enough to keep the crew alive, but only if nothing bad happens (yes, there are safety systems and redundancies, but they are still gossamer boxes). The station at the top of the elevator would be able to be built much more robustly, with armor, shielding, hydroponics, and expanded living spaces, etc. It would a much tougher nut to crack, and subsequently a much safer place to do work.
It would become the hub for an entire industry in orbit. Orbital manufacturing would open the door to new classes of materials that could be used in space, or on Earth. Shipyards would be able to build ships that could go out and fetch nearby asteroids for mining (these could be unmanned, even – a robot can fly to a rock, attach to it, and boost it back to Earth; it would be slow, but doable, and cheap). The rocks could then be mined in ways we can’t do on Earth and the resulting material could be used in new orbital construction, or sent down the cables back to Earth. It may even become more cost effective to mine asteroids and process them in orbit than it would be to bother digging around in the Earth. Such things would mean more jobs for people, and believe it or not, you don’t need a PhD to work in space. You don’t even need a degree, just some expanded safety training, very similar to what a lot of Navy sailors & hazardous industry workers already get.
And if we figure out how to build fusion power plants, then our ability to flourish in space will only improve.
How About The Negatives?
Yes, there will be bad things. Space is still dangerous, people will be injured and killed working in space. Some idiot will cut some corner and someone else will pay the price. Avarice, Corruption, and Stupidity will find their way out there. We do the best we can and try to make the good far outstrip the bad, as we’ve always strived to do.
Expanding into orbit, and into the solar system, will allow humanity to grow and advance in ways Science Fiction authors and Futurists have been trying to imagine for decades. Such advances will present us with new challenges to face, but also new opportunities to improve the human condition.
 As per Douglas Adams, the secret to orbiting a planet is to fly at it and miss in a very precise way. Also, I know Force and Energy don’t exactly balance. Except they do if you think in terms of Kinetic versus Potential Energy.
 This is analogous, but it is NOT how orbital mechanics works. It is merely a useful way to visualize it.
 Think about metals. A micro-gravity or zero-G foundry would offer us a whole host of new ways to work metals, because without gravity, metals cool and solidify in some very unique and useful ways. This can vastly improve the properties of the metals. There are hundreds of other manufacturing and industrial processes that behave in exciting ways in zero-G, and that is not even taking into account the fact that a facility that works with hazardous chemicals is less harmful to the Earth up there than down here.
 A Reactionless Drive is one that does not eject mass in order to create acceleration. Even Ion Drives are reaction drives, since the emit ions. A reactionless drive can consume mass in order to create energy, but the energy would then be used to power some kind of field effect that would allow the vehicle to move. Think Star Trek – the Enterprise created a warp field and then by manipulating that field, caused the ship to move about. We can theoretically create such fields and use them to move, but the energies required to do so far exceed what we can create or store in a vehicle.