Image credit: Reaction Engines Limited publicity art.
The British Broadcasting Corporation featured an interesting article on a British technology effort last week:
UK engineers have begun critical tests on a new engine technology designed to lift a spaceplane into orbit.
The proposed Skylon vehicle would operate like an airliner, taking off and landing at a conventional runway.
Its major innovation is the Sabre engine, which can breathe air like a jet at lower speeds but switch to a rocket mode in the high atmosphere.
Reaction Engines Limited (REL) believes the test campaign will prove the readiness of Sabre's key elements.
Key Tests For Skylon Spaceplane project
The BBC article explains in some detail what the "key element" is, but essentially it's a means of using the space plane's own fuel to cool the air coming into the engines enough so that it doesn't melt them. At the speeds such a craft must travel, both entering and leaving the atmosphere, that's a big consideration.
What's so exciting about this development, a test in what will undoubtedly be a long series of tests of an experimental design that probably won't exist for at least a decade? It's exciting, because this is, as the BBC article goes on to say, an enabling technology for a single stage to orbit (SSTO) design. SSTO is, if you will, the DC-3 of spaceflight - a design strategy that changes achieving orbit from something that only countries and a few mega-corporations can do to something that is within reach of any mortal who was a few hundred thousand dollars to throw around.
In a sense, it opens the solar system to the rest of us, because when it comes to going from Earth to most places in the solar system, getting out of Earth's gravity well is a big part of the problem. The huge rocket engines of the Saturn V and the Space Shuttle were mostly needed to get them into orbit. Once Apollo was there, for instance, the relatively minuscule rocket motor on the service module could get it to the Moon and back. Once you're in orbit, a relatively small push at the right time can get your spacecraft going in the direction it needs.
Right now, getting out of the gravity well requires huge, expensive rockets, the vast majority of which are used only once, then discarded. A space plane, or other SSTO design, makes it possible to re-use the majority of the spacecraft, making more or less regularly scheduled service practical. This is how REL envisions such operations:
SKYLON has been designed as a practical utilitarian machine for use by competitive commercial operators. This is seen as the most effective way to ensure that space transportation assumes its proper place in the economy and its continued improvement under "customer control". This has dictated a configuration as close to a conventional aircraft as technology will permit. In particular a rolling take-off has been seen as essential.
Caption: SKYLON Maintenance Hangar
Image credit: Reaction Engines Limited publicity artInitially operations will probably begin from existing sites built either for space or aircraft which have been modified to suit SKYLON vehicles. However in the longer term (within ten years of introduction) operations would probably move to international equatorial sites since these offer maximum launch opportunities of at least two windows per day and access to any orbit. For easterly missions there is also a performance advantage due to the earth's rotation.
The eventual equatorial launch sites, or spaceports, are envisaged to be international from the point of view of the operators using them and would be established by share investment; profits would be made by leasing the facilities to the spaceline operators. It is expected that three spaceports would be operating at equatorial locations by 2020-2025.
SKYLON - Commercial Operations
As REL's design goals page states, the SKYLON, if it is ever built, will be a completely automated system. There will be no human pilots on board. It should be able to take ten tons of cargo to low earth orbit (LEO) to destinations such as the International Space Station. Eventually, REL believe they will be able to take as many as 30 passengers into orbit, once the design has been demonstrated and refined sufficiently. That means it should also be able to bring ten tons or so back to Earth, making it possible to retrieve satellites and other things that are in orbit, and bring them back for maintenance.
It will also be expensive to operate. As this cutaway shows, most of the vehicle will be filled with hydrogen propellant. For anyone who remembers early aviation history, that's a big blinking warning sign that there will have to be a lot of careful planning and procedures needed to operate this vehicle safely. Any machine that can go boom that readily has to be treated with respect.
Image credit: Reaction Engines Limited publicity art
Compared to the months of preparations required for the launch of a large space rocket, though, operating a design like the SKYLON sounds like a walk in the park. Of course, it's not a walk in the park. It's a complex machine with many complicated, state of the art, potentially dangerous parts. Developing it will cost lots of money.
How much money is the REL program costing the United Kingdom? The Beeb article offers a glimpse at the financing question:
So far, 85% of the funding for Reaction Engines' endeavours has come from private investors, but the company may need some specific government support if it is to raise all of the £250m [$300m] needed to initiate every next-phase activity.
"What we have learned is that a little bit of government money goes a long way," said Mr Bond.
"It gives people confidence that what we're doing is meaningful and real - that it's not science fiction. So, government money is a very powerful tool to lever private investment."
Key Tests For Skylon Spaceplane project
As a rule of thumb, I assume a UK pound is worth about $1.25. That's a good round number for estimating. Using that figure as a basis, I added the dollar estimate to that article.
Image credit: Reaction Engines Limited publicity art.
Of course, these are early development costs. It's also the early, optimistic days of this particular project. The reality of cutting-edge research and development is that you won't know the cost of producing the first machine until it rolls out the door, because there will be unforeseen, and unforeseeable, bumps in the road along the way.
Still, it's interesting to contrast that number with this slide from the U.S. Department of Defense's FY 2013 budget proposal:
The money the DoD thinks it wastes on travel alone could fund this project. There's also this slide on some of DoD's priority projects:
The DoD space budget could fund at least twenty projects the size of SKYLON simultaneously. Of course, SKYLON will become far more expensive once its engineers start turning it into an actual machine, but the difference is still staggering.
Finally, here's a segment of the table I published in "World Military Spending: 2011" a few days ago:
| Rank 2011 (2010) | Country | Spending ($b, MER) | Change, 2002–11 (%) | Share of GDP (%, estimate)a | World Share (%) | Spending ($b, PPP)b |
|---|---|---|---|---|---|---|
| 1 (1) | United States | 711 | 59 | 4.7 | 41 | 711 |
| 4 (3) | United Kingdom | 62.7 | 18 | 2.6 | 3.6 | 57.5 |
| World | 1735 | 42 | 2.5 | 100 | ||
Go to the link for more detail. The important thing to note here is that the U.K. spends roughly the same proportion of its gross domestic product (GDP) that the world generally does on defense. We spend nearly twice that. If we only spent 2.5 percent of our GDP on defense, we'd save roughly $330 billion a year. That's a thousand SKYLON projects at its current level of funding. It's 17.5 times NASA's budget. It's ten or more times the National Institute of Health's (NIH) (PDF), and at least half again more than the biggest budget proposal (PDF, page 4) I've seen on infrastructure spending lately.
That's a gods-awfully huge number, by just about any stretch of the imagination, and yet it is hard to avoid feeling that this really is a priority of Americans generally. How often do people in this country say that we spend far more on defense than we need to? Once you discount a few "extreme" progressives and conservatives, not a whole heck of a lot, in my experience. Yet the difference between what we're spending and what our peers are spending could fund just about all the things we're told we just don't have money for, like all those things I mentioned in the last paragraph, plus decent education and health care for all of us.
At some point, being better at blowing up other peoples' countries really does start to cost us the ability to improve our own. What this little story ought to demonstrate is that, in many ways, we are there. Not only are we giving up the space planes of the future, but, more importantly, we're giving up the transportation infrastructure that could get us to them, and the education needed to design, build, and maintain them.
I don't know about you, but I'm not so afraid of the rest of the world that I'm willing to give all that up.
UPDATE: I added some links supporting the NIH and transportation budgets, and adjusted the verbage accordingly. Originally, I'd said that the $330B difference was "more than a dozen times" NIH's budget, and "at least three times" the biggest proposal I'd seen. Turns out, it's a little less, but not outrageously so, IMHO.
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