The problem with space travel is money. The cost of reaching low
earth orbit from the surface of the earth needs to drop by a factor
of 20 or more.
At the moment, space flight is expensive and has few users:
* the military: long range artillery, espionage, weather forecasting,
communications relay
* everyone else: earth resources investigation, weather forecasting,
communications relay
Scientists are also provided some funding,
Sadly, the current demand for space flight will not much increase
even if the cost to carry a ton into orbit is halved or quartered.
For a US presidential commitment to look like something other than a
warning to the Chinese and an election year gambit, the president must
commit the country to lower the costs of going into orbit radically,
by a factor of at least 20.
If the cost comes down to a level that people and ordinary businesses
can afford, then we will see a huge increase in demand -- whole new
industries will be invented or existing industries changed. But not
until then.
Unfortunately, the major US and foreign companies in the space
business have no incentive to reduce costs dramatically: to do so
would also reduce their profits dramatically. Not only that, such a
cost reduction would require they abandon their current more or less
predictable future for one that is full of organizational unknowns.
The companies do have an incentive to keep track of possible cost
cutting technologies, in case someone else introduces them. Hence,
the various `advanced' research projects you can read about. Also,
these projects make for good PR. However, unless the alternative is
to lose their current business, the companies have no reason to
institute programs that would reduce their current profits and not be
predictable by current `good business' criteria.
In addition, as an organization, NASA has no incentive to cut launch
costs radically. For one, NASA employees can clearly foresee both
their future and that of their organization when the current methods
are followed. Moreover, much NASA development is actually done by
companies and some think of the agency as a mechanism to provide
corporations with disguised welfare. (Scientists, engineers, and such
like people think differently; but they don't count bureaucratically.
They are useful for creating things that produce good PR, like the
Hubble space telescope, and the current unmanned landing on Mars.)
Worse, the US government can clearly see the military danger of
relatively inexpensive earth to orbit travel: another country could
launch several dozen space ships that appear to be normal, civilian
craft. They will cross over the US; it could be arranged that all
cross the US as the same time, apparently accidentally. If they carry
bombs, they could launch them with almost no warning. Large weapons
could be detonated in orbit, not giving any warning at all. (It is
for this reason that I expect that the US and other countries will
insist on an inspection regime.)
For these reasons, I do not think the Bush proposal means much, except
as a way to stop spending on space telescopes, missions to Mercury,
asteroids, and Pluto, and on advanced earth resources research.
As for inexpensive earth to orbit travel: there are two obvious ways
to achieve this:
* A nuclear thermal rocket. The initial US research in the 1960s
did not do so well (rocket engines crumbled) but eventually tests
lasted "until the hydrogen ran out". One kind of rocket engine
produced too low a thrust, given its mass, for lift off the
planet; but other kinds had thrust-to-mass ratios of 30 to 1 and
could be used in a single stage to orbit rocket. These are for
tested nuclear rocket engines. There are some really interesting
`advanced' designs, too. I have been told that a nuclear rocket
development program, leading to a viable current design, would
cost no more than $5 - 10 billion US dollars. I don't know
whether this is true.
The problem with nuclear thermal rockets is two fold. Firstly,
the current designs always put some radioactive fission products
into the exhaust. The impression I get is that the releases per
launch are less than a 1 GW coal-fired electric power station puts
into the air (from uranium dust in the coal that goes up the smoke
stack). But I don't know.
Secondly, some nuclear thermal rockets will crash. That is
inevitable, just as some nuclear submarines have sunk. Launch
trajectories can be designed so that not too much damage is done
by a crash; but people will worry. How confident are you that
Russian or Ukrainian built vehicles will safer than the nuclear
power station at Chernobol?
The way to reduce the number of crashes is to reduce the number of
rockets, planet-wide. This raises the price of going into orbit
and reduces the military risk. It also means that the great
powers have to police every technologically adept country to
prevent them from building and using such rockets.
* An air-augmented chemical rocket. Currently, rockets carry all
the oxygen they need with them. An air-augmented chemical rocket
operates part of the time as a ram jet, taking in oxygen from the
atmosphere. This reduces the mass of oxidizer the rocket must
carry.
It is difficult to develop this combination of ram jet and pure
rocket, but not impossible. (If I remember rightly, the current
jargon calls this kind of rocket a `combined cycle' engine because
it can operate as a subsonic ram, a supersonic ram, a hypersonic
ram, and as a pure rocket. I am using a name that is more than half
century old.)
Another developement difficulty is the speed at which fuel burns
in a ram jet: when the jet is traveling hypersonically, the fuel
has a very short time to burn in the thrust portion of the engine.
(I don't say `tube' because some designs use a hypersonic shock
wave as one side of the engine.) However, I think this problem is
being solved.
As with a nuclear rocket development program, I have been told
that an air-augmented chemical rocket development program would
cost no more than $5 - 10 billion US dollars. I don't know
whether this is a valid estimate or simply a number chosen as
politically expedient -- that is to say, an amount larger than
most private investments, but small enough for any of five or ten
large country governments.
Because they are not nuclear, air-augmented chemical rockets could
become widespread. They pose the same accident danger as
airliners. The military danger can be overcome with inspections.
Of course, air-augmented rockets, like current airliners, put water
into the stratosphere. Some have argued that this water is or will
upset the climate. The US is covered with contrails, which are a
visible indicator of such water. And over the past 30 years, people
have seen a decrease in the amount of measured sunlight in western
Europe. (And maybe elsewhere; I don't know.) I have heard talk that
airliners should fly lower, which uses considerably more fuel, so as
to put less water in the stratosphere. I don't know the science of
this, nor how many air-augmented rocket launches would be acceptable.
Recently, I read that India is developing a hypersonic, combined cycle
airplane that will also carry payloads into low earth orbit. India
might do this: it does not already have a large program using
current, expensive technologies, so there is no organization
motivation to stick with what exists. And members of the Indian
establishment want the country to become a great power. We will find
out about India in five or ten years.
Meanwhile, back to my main point: unless he proposes to reduce the
cost of leaving the planet, it is impossible to conceive of President
Bush's proposals as more than an election year boondoggle and the
beginning of a competition with the Chinese.
Some people speak of the pride his proposal generates: that is wasted
emotion. The proposal, as given, makes the cost too high.
Consequently, only a few could visit Mars. The technology is not
sustainable, except as a government luxury or substitute for war, like
the Apollo Project.
While I favor substitutes for war, I see no point in wasting the money
spent on them. The US decision to go for a lunar orbit rendezvous in
the early 1960s was shortsighted. It delayed construction of a
(mostly US) earth orbiting space station for a generation. (The
initial Soviet space stations were from single launches, like the
1970s US Sky Lab space station. Their `Mir' station was made up of
separately launched modules, starting in the mid-1980s. The US did
not begin the ISS until the 1990s.)
The decision for lunar orbit rendezvous was made because it speeded up
the development of a vehicle that could carry two men to the moon.
However, I would have preferred that the first US moon landing have
been delayed a year or two, and that we now already be on Mars, and
that space travel as such be more than paid for by asteroid mining.
It is fine to admire heros who go some place, and not visit the place
yourself. But when a government invests in a technology that is too
expensive, the program can be canceled by a new government. In the
early 1400s, Chinese fleets explored the ocean. These fleets were
vast and the ships were more advanced than contemporary European
efforts. But the program was canceled. Less than a century later,
the previously backward Europeans sent ships into the waters that the
Chinese has previously considered theirs.
If the cost of going into orbit were radically lowered, then funding
would come from many more sources than the government. A government
might cancel a program. It would not matter. Mining and
manufacturing, and even off-earth colonization, would become feasible.
Rather than depend on a few governments, their boondoggles, or their
conflicts, efforts at discovering what the rest of the solar system is
like would prosper. Scientific research would be less expensive, and
therefore more likely to gain funds.
--
Robert J. Chassell Rattlesnake Enterprises
http://www.rattlesnake.com GnuPG Key ID: 004B4AC8
http://www.teak.cc [EMAIL PROTECTED]
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