Issue 16, 1 January 2007 -- 38th Apollo Anniversary Year

  1. Spaceflight in 2006: A modest recovery
  2. Analysis: Stepping up from suborbital to orbital commercial spaceflight
  3. Report: The 2006 BIS-BNSC space tourism conference

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(1) Spaceflight in 2006: A modest recovery

The human presence in space made a modest recovery in 2006 from its post-Columbia low of 794 man-days spent in space (2004), reaching a total of 1210 man-days accumulated over the calendar year.

There were five manned launches: Soyuz TMA-8, STS-121 (Discovery), STS-115 (Atlantis), Soyuz TMA-9, and STS-116 (Discovery), all of which successfully reached the ISS. A total of 28 different people spent between 10 days and 6 months each in space, and 3 of them remain on board the ISS to celebrate the New Year.

There were no dedicated commercial manned launches, though Soyuz TMA-9 carried Anousheh Ansari on a private mission organised by Space Adventures. Ansari is the fourth private visitor to the ISS after Dennis Tito (2001), Mark Shuttleworth (2002) and Greg Olsen (2005). She is the sixth non-government space traveller overall, including Toyohiro Akiyama (1990) and Helen Sharman (1991). And she was on the seventh privately organised manned space mission, including the Soyuz TM-30 Mircorp rescue mission (2000).

The most active calendar year in manned spaceflight remains 1997, with 1746 man-days spent in space and 10 launches (there were also 10 launches in 1992 and 1994, and 11 in 1985, but with less total time logged in space).

On 2 November 2006 the International Space Station passed its sixth year of continuous occupation (not counting the first two-day taxi flight to reach it). The record currently remains the second long-term occupation of Mir, at 9 years 354 days, which the ISS will exceed on 22 October 2010, if all goes well.

Discovery remains the most travelled Shuttle orbiter, with 33 missions completed successfully over the 23 years since it was built. Its December 2006 mission (designated STS-116) was the 117th Shuttle launch, and the 115th Shuttle mission to be completed successfully.

Of particular interest to those of us in Europe in 2007 will be the first launch of an ATV to the ISS in May, and in October the launch of the 6.5 billion euro Columbus laboratory on Discovery (close to the 50th anniversary of Sputnik 1). Test flights of SpaceShipTwo are also expected before the end of the year.

-- S.A.

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(2) Analysis: Stepping up from suborbital to orbital commercial spaceflight

by Stephen Ashworth

Many people have pointed out a supposed gap between suborbital flights, such as those of SpaceShipOne and the soon to be launched SpaceShipTwo, and spaceflight into low Earth orbit.

Certainly, there is a gap at present. Flying on a suborbital shot to 100 km altitude, like SpaceShipOne or the Bristol Spaceplanes Ascender design, requires accelerating to a speed of about Mach 2.8, whereas getting into orbit demands Mach 25 (=7.8 km/s) -- almost 9 times faster. The kinetic energy of an orbiting vehicle at burnout is therefore 80 times greater than that of the same vehicle at burnout on the lowest possible suborbital lob (the energy increasing with the square of the speed), and the energy expenditure to enter orbit is even greater, due to the inefficiency of having to carry rocket propellants to the point where they are to be used.

How then can SpaceShipTwo and its rivals have any relevance at all to true space access?

Any vehicle consists not only of a physical object that one can ride in, but also a business plan -- some reason for its existence, a method in which the builder expects it to be used, a market where it is in demand. The business plan of the suborbital space tourism manufacturers and operators is dramatically different from that of the government space agencies. In particular, it provides for competition between different operators of the transport service, such as Virgin Galactic, PlanetSpace and Space Adventures (which is also reportedly going into suborbital flights), and between different builders, which currently include Blue Origin, Canadian Arrow, Prodea, Rocketplane, The Spaceship Company (jointly owned by Scaled Composites and the Virgin Group), and others.

As soon as two or more operators actually start a service to 100 km and return, they will begin to ask: why stop there? Clearly, if your competitor is flying to 100 km, the commercial pressure is on you to fly to 120 km, to give your passengers a few more precious minutes in space. Burning that little bit more rocket propellant is only a minor additional expense. That puts the pressure on the other company to fly to 140 km, and so on, like the competition between steamship companies a century ago over who could achieve the fastest Atlantic crossing (though that was far more restricted by the available technologies of coal and steam).

Suborbital doesn't have to stop at 100 km -- after all, the astronauts blasted into space by the Columbiad cannon in Jules Verne's 1865 novel "Round the Moon" were on a suborbital flight -- it just happened to go to an altitude of 358,658 km (the Moon being at perigee at the time).

Is there a suborbital flight with the same energy requirement as a flight into low Earth orbit?

The velocity at any point on an elliptical orbit depends on the semi-major axis of that orbit, but not on the eccentricity. The velocity of 7.8 km/s of a vehicle in low Earth orbit is oriented parallel to Earth's surface. If the same speed at the same altitude above the surface is oriented vertically, then a vehicle with that velocity will soar to an altitude of about one Earth radius -- it will execute a suborbital hop to an altitude of around 6500 km, and a simple calculation shows it will be in space for about 70 minutes.

The same vehicle flown horizontally rather than vertically would go into low Earth orbit -- the requirements for launch power are exactly the same, while reentry from orbit would actually be easier than from a high suborbital hop, as the descent into the atmosphere would be more gradual.

What about the Van Allen belts? Giving one's passengers radiation sickness could be very bad for business.

The inner belt begins to build up its radiation intensity from around 700 km altitude, though this would not necessarily be a problem for a brief visit. (ESA's newly launched Corot astronomical satellite is designed to function for years quite happily at an altitude of over 800 km.) But in any case the belts are concentrated within +/- 20 degrees latitude of Earth's magnetic equator -- Apollo flights were specifically oriented so as to avoid these equatorial regions (see http://www.clavius.org/envrad.html). Suborbital shots launched from say Canada or Alaska, or in the southern hemisphere Australia or New Zealand, would be close to the magnetic poles (currently located at roughly 82 deg. N, 113 deg. W, and 64 deg. S, 138 deg. E, though they do wander from year to year).

Suborbital flights from these locations would therefore be relatively safe for passenger flights to any altitude, and offer a continuous gradient of increasing altitude which painlessly closes the gap all the way from suborbital to orbital propulsion and reentry technologies.

So we do not need a specific plan or programme to evolve private sector passenger spaceflight from suborbital to orbital. Once suborbital is established, and providing that the market for it remains healthy and that there is a diversity of competing providers, the mechanisms of the market and commercial prestige will ensure that evolution will occur -- quite apart from the obvious demand for orbital spaceflight in any case.

According to Sir Richard Branson, the industry is no less than "the foundation for the human colonisation of space". It is so, not so much because of any specific spacecraft or design, but because -- unlike government -- it has a business plan that can drive continually increasing capabilities.

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(3) Report: The 2006 BIS-BNSC space tourism conference

by Stephen Ashworth

On 29 November, nine speakers addressed various aspects of European developments in space tourism in a spacious conference room at the Department of Trade and Industry in Victoria Street, thanks to the generosity of the BNSC in sponsoring the event.

Ian Gibson for the BNSC surveyed Britain's current strengths and weaknesses in space, and concluded with the hope that our strengths would soon include space tourism and low-cost launchers.

Steven Fawkes, a consultant in the energy industry, stressed sustainable development. This was also a key theme of the presentation by Dave Robson of EADS Astrium, who said: "Space is not black. Space is green! -- every bit of infrastructure we put in space makes Earth greener."

Julia Tizard presented the latest news from Virgin Galactic, including a video of Sir Richard Branson, and another showing an animation of the experience which SpaceShipTwo will offer to its passengers. Test flights are scheduled for the end of 2007, and the first passengers will be carried in 2008 or 2009. She concluded: "Sub-orbital tourism is very achievable and is becoming tangible."

David Ashford, of Bristol Spaceplanes Ltd and the organiser of the conference, offered the following vision for Europe: "To take the lead in developing airline travel to orbit, resulting in large scale space tourism and a 1000 times reduction in the cost of access to space."

A lively discussion followed the presentations. All the speakers agreed that the largest near-future benefit of manned spaceflight was its potential to create a mass market, and thus bring down the cost of space travel by orders of magnitude.

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Astronautical Evolution is an e-mail newsletter devoted to debate and comment from an astronautical evolutionist perspective. To subscribe / unsubscribe / contribute / comment, please e-mail Stephen Ashworth, sa--at--astronist.demon.co.uk.


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