Saturday, March 1, 2014

The Sad Reality of Space Travel

Whatever happened to the Space Race?  We were supposed to be living in domes on the moon by now.

When I was a kid, we were in the Space Race, and we were told than within our lifetimes, we would see colonies on the moon, space travel to Mars, and maybe even colonization of Mars as well.  Trips to Jupiter and the asteroids, of course, would be next.   

By 2001, we were told, Pan Am would be running regular shuttle service to a slowly rotating space station, which would be jointly financed by the USA and the USSR.   And giant space craft would be sent off to explore Jupiter and Saturn, with astronauts in "suspended animation."

And who knows?   Maybe in a few hundred years, we would develop a "warp drive" and travel to the stars, like Captain Kirk,

Sadly, none of that happened, although we have seen a lot of progress in space exploration, albeit mostly by robots.

What happened to these wild plans?   Well, the reality of space travel happened.   Optimistic scenarios failed to play out, simply because of basic physics.  What sort of things am I talking about?  Well, here are a few of them:

1.  Gravity Well:  We live at the bottom of a gravity well of 1g.  In order to get something out into space, it takes an enormous amount of energy to lift it.   Thus, in order to build that space station (which we have, in a manner of speaking) you have to spend an enormous amount of money to boost all those parts into space.  As it turns out, we don't have that kind of money - to launch huge space stations, or to send huge quantities of manufactured goods to the moon and elsewhere.  We've built three low-orbit space stations to date.  Two of them (Skylab and Mir) have since fallen back to Earth.

2.  Orbital Mechanics:   In space, everything is orbiting something else.  In cheesy Science Fiction shows, people say dumb things like, "We're outside the pull of gravity from planet X, Captain!" as if you could just get far enough away from a planet, and gravity would die down.   The reality is, you have to go into orbit around an object to escape its pull, and to achieve this, you have to exceed what is known as "escape velocity" - which is why rockets have to go so darn fast.   When you want to return to the surface of a planet, you have to bleed off all this speed.  Since carrying enough fuel to slow down is cost-prohibitive (see Gravity Well, above), most spacecraft use a form of atmospheric braking to slow down.  This means a risky high-temperature high-speed dive into the atmosphere of a planet, which requires esoteric high temperature materials for your rocket, and little or no margin for error.

3.  Suborbital Flight:   "But," you say, "That Virgin Airways guy and Burt Rutan have designed a passenger rocket that will go into space!"  And that is true, but at the present time, it is a suborbital flight.  It will not exceed the escape velocity needed to go into orbit, nor does it have the heat-proof exterior to survive the aero-braking of re-entry.   It goes straight up, pauses for a moment, and then drops back to Earth.  While it is still an amazing accomplishment, going orbital is an additional quantum level of complexity.  Perhaps they will achieve this, we'll see.

4.  Going to the Grocery Store in a Dragster:   One of the most ridiculous things about space flight is rocketry.   You set up this Empire State building of fuel, with a tiny capsule or space-plane on top of it.   You light the fuse and watch it go up.   The problem is, you've used up half your fuel before you've cleared the tower.   It is like driving to the grocery store in a dragster.  It makes little or no sense to carry oxygen aloft for that portion of the flight that passes through an oxygen-rich atmosphere.  And this is where, perhaps, the Virgin space plane may succeed, as it can be launched in mid-air, and have some initial altitude and velocity without having to accelerate from zero elevation and zero velocity.

5. The Danger:   We were told that Space Shuttle flights would become as routine as flying in an airplane, and that soon, everyone would take a vacation in space.  Reality turned out differently.   Space travel is very dangerous, simply because when something goes wrong, you are surrounded by either vacuum or tons of fuel, or you are going very, very fast (or all three).  Apollo 1 taught us that just sitting on the pad can be fatal.  Apollo 11, viewed as a success, was seconds away from running of fuel, when Neil Armstrong landed the LEM manually.  Apollo 13 showed how fragile the systems of the spacecraft were - one flaw could literally blow the whole thing apart.  Since then, we've had two shuttle disasters, both caused by small failures of individual parts which are among the millions of components of the craft.   All it takes is one oversight and things blow up.   The Russians are not immune, of course, but are known to have buried their mistakes, supposedly leaving dead Cosmonauts in orbit.   Space travel, due to the high velocities, absolute vacuum, and staggering amount fuel (as well as complexity of space vehicles) will always have a high level of danger, and never achieve the level of safety of airlines - it is basic physics.

6.  Vacuum and Radiation:  One reason we never built colonies on the moon, in addition to the staggering costs involved, is that it is very hard, if not impossible, to live on the moon.   Sure, if you threw a firehose of money at our satellite, you could support a colony there.  But they would have to live underground, and be at the mercy of moonquakes, meteorites, and basic industrial accidents.  One failure of a seal or a weld, and an entire colony could go "poof" in an instant.   Building a truly self-sustaining colony would be a staggering proposition - and would require an enormous population of people, as well as hundreds, if not thousands, of miles of tunnels, to provide all the agricultural as well as industrial needs of such a society.   Think about it - living underground would mean having to supply lights, wiring, controls, and other manufactured goods, just to survive.  To be self-sufficient, you'd have to mine the minerals to make these things, and than have the manufacturing machinery to build everything from plumbing pipes to LEDs, to semiconductor circuits.  The energy required would be staggering as well. And let's not talk about basics like water and oxygen.    And at least initially, heroic amounts of supplies would need to be shipped from Earth to Moon, every week, just to sustain such a colony.

Mars is no better, and being further away, makes the trans-shipment of cargo even more difficult and expensive.   The presence of water on Mars might help, but the thin atmosphere means that people would be living under domes their entire lives.  We could not "Terra-form" Mars with any ease.

Any colony on the Moon or Mars would be governed by a military-like dictatorship.   When one small leak or crop failure spells doom for all, the idea of "personal freedom" would be very limited, if in fact, non-existent.  Such a society could not allow for troublemakers, slackers, unemployed, homeless, the mentally ill or even retirees.  It would be a brutish environment for survival, and as a result, the social living conditions would not be ideal.  Once you were no longer a productive citizen, it would be out-the-airlock with you - without a spacesuit.  The idea that somehow we can colonize Mars and "start over" with a new society (and put all of Earth's troubles behind us) is fundamentally flawed.   We are stuck here on planet Earth.

7.  Space Junk:   In addition to the field of crap we have created, orbiting our planet, space turns out to be anything but a total vacuum.  Look at the moon sometime, and ask yourself how it got to be that way.  Meteors plowed into the surface of the moon (and Mars, and yes, even Earth) and blasted it - each producing the impact of a nuclear weapon - or far more.   The extreme velocities that spacecraft travel at (as well as space junk) means that even a small impact with a small body can product catastrophic results.  The space shuttle hit a orbiting fleck of paint left in orbit by a Soviet rocket - and it nearly destroyed the windshield.   Larger objects at larger velocities would go off like a hydrogen bomb.   The soft, cushioning atmosphere of our planet protects us from all but the largest of these hazards.  Colonies in space, on the Moon, or even Mars, would not have such protection.

Interstellar space is even worse.  There isn't a lot of stuff out there, except perhaps cosmic dust.  But the velocities needed to reach even the nearest stars (0.5c or greater) would mean that any collision would release atomic-bomb-like energies.   Interstellar space travel, using conventional (sub-light-speed) means of propulsion, would be a very dangerous proposition.

8.  Time:   Despite the heroic velocities of spacecraft, it takes a long time to get anywhere in space, just because there is so much of it.   A trip to Mars, for example, could take months, and just supplying all the food and water for such a trip (even with recycling) is a staggering proposition.  Interstellar trips could take years - or even generations - and require enormous ships and supplies.   To get around this, science fiction writers posit some sort of "deep sleep" or "suspended animation" that would allow people to sleep through such a trip, using little in the way of food or water.  But such techniques have yet to be invented, and it is questionable whether they could.   It is possible to put someone in an artificial coma. The problem is, you then need three people to tend to that person.

The time problem makes traveling to other planets in our solar system difficult.  Immense amounts of supplies are needed.  In addition, there are psychological effects of being in an enclosed spacecraft with a small group of people.  Already we have had incidents on Skylab, some Apollo flights, and some space shuttle flights (as well as in the International Space Station) where astronauts have gotten into conflicts with ground control, or each other.   A three-month flight to Mars could post enormous problems, as small groups of people, in close daily contact, start to resent one another.

For interstellar flights (if such a thing was even possible) we have the additional problem of time dilation, which would mean that if you went to Alpha Centuri and back, everyone you know would be dead, and maybe one-hundred years would have elapsed.   The idea of interstellar commerce, at sub-light speeds, is thus ridiculous.   Even if it would be cost-effective to ship goods between the stars, by the time such goods arrived, the people who ordered them would be dead.   The idea of a "space freighter" is a nice fiction only.

And this goes for the idea of Extraterrestrial communications as well.   Even if we could pick up some signals from our SETI project, the aliens sending them would be long-dead by the time we got them, and by the time we got their return signal, we'd be dead as well.   And by the way, one reason we aren't getting signals from outer space is that ordinary radio signals do attenuate over distances.  People on Alpha Centuri III are not amusing themselves right now by watching re-runs of I Love Lucy, simply because those signals don't reach that far.  Sorry.

9.  No Warp Drive:  Science Fiction writers use a McGuffin to get around all of this. To create interstellar travel, they just say "well, they use warp drive, or wormholes, or drive through a black hole or something."   And you need this premise in order to make any kind of Space Opera work.   But there is no real theoretical basis for warp drives, at least at the present time.  Such a technology - even if it could be made to work - would be Centuries in the future.   But frankly, I am skeptical that such things exist or could exist.   Science doesn't give away freebies.  Entropy must be fed.

As for driving through black holes, forgetaboutit!  If you even  got close to one, the tidal gravity forces would squash you and your spaceship flat as a bug.  You might as well try to fly into the sun.

* * *

So what does this mean?   Should we not have these dreams?    Well, it is fun to dream, or go to a Sci-Fi movie or read a Sci-Fi book.   But the reality is, we are basically stuck here on planet Earth.  Even assuming you could colonize the moon or Mars, there would be no migration of mass quantities of Earthlings to other planets.    We are stuck here - get used to it.

The good news is, of course, that we live on the nicest planet in our solar system.  Yea, it is a little run down in places, and a lot of people don't appreciate how nice it is.  But living under the blanket of an atmosphere allows us an enormous amount of personal freedom that you would never see in a space colony.

Maybe we should think about taking better care of our planet and ourselves, rather than looking to moon colonies or Mars colonies as the "answer" to anything.

Because the sad reality of space travel is that it will always be expensive and dangerous, for the foreseeable future.  It will be interesting to explore our little solar system and see what's about - probably mostly by robotic probes, at least initially.   But the major lesson we take away from these explorations is how lucky we are to live where we do - and how we should take better care of the one planet we've got.

1 comment:

  1. With regard to the gravity well, please, no more talk about "Space elevators". The space elevator idea was that you could put a satellite in geostable and geosynchronous orbit and then just toss down a rope and haul people and things up.

    Several problems with this. First, this rope would have to be super-strong and lightweight, as it would be about 22,000 miles long and weigh millions of tons by itself.

    Second, the gravitational effects are interesting. It turns out, after doing experiments with "tethered satellites" from the space shuttle, that these cables would tend to form a spiral, not a straight line out to your satellite.

    In other words, it wouldn't work. If you could even have this magic rope and hook it up somehow (how?) and started hauling things up, it would just yank your satellite out of space.

    And if the rope broke, imagine a few million pounds of 22,000 mile long rope falling through the atmosphere.

    No, sorry. Ain't gonna work. Physics just isn't generous like that. No free lunches.

    Space travel will always be expensive and risky, just because of the basic Physics involved.

    ReplyDelete

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