All Astronautical Evolution posts in 2014:
The SpaceShipTwo Crash (Nov.)
To the Rt Hon Greg Clark (Oct.)
A Four-Point Plan for ESA (April)
New in 2020:
2021: New space company Planetopolis…
2020: Cruising in Space…
2019: The Doomsday Fallacy, SpaceX successes…
2018: I, Starship, atheism versus religion, the Copernican principle…
2017: Mars, Supercivilisations, METI…
2016: Stragegic goal for manned spaceflight…
2015: The Pluto Controversy, Mars, SETI…
2014: Skylon, the Great Space Debate, exponential growth, the Fermi “paradox”…
2013: Manned spaceflight, sustainability, the Singularity, Voyager 1, philosophy, ET…
2012: Bulgakov vs. Clarke, starships, the Doomsday Argument…
2011: Manned spaceflight, evolution, worldships, battle for the future…
2010: Views on progress, the Great Sociology Dust-Up…
Index to essays – including:
The Great Sociology Debate (2011)
Building Selenopolis (2008)
Creating a Future with Skylon
Stephen Ashworth, Oxford, UK
A project “achingly close” to realisation
Around 90 people turned up to hear Mark Hempsell’s evening talk at the BIS on Wednesday 22nd – a record audience for the British Interplanetary Society in recent years, and one which necessitated hiring a larger hall for the evening. Despite the gloomy Victorian church architecture, the focus was resolutely on the disruptive near-future technology represented by Britain’s Skylon single-stage-to-orbit spaceplane programme.
Although Mark has left his official position at Reaction Engines, he is still very much part of the broader Skylon team. He reported that the feeling within the project is that it is now “achingly close to being realised”, thanks to recent UK government support and “spectacular angel financing”, which has “brought us to a unique point in astronautical history”. (Worth remembering that this project has been in gestation since Alan Bond began work on what is now the Sabre engine in 1982, more than thirty years ago.)
Skylon offers “a perfect match” with the official requirements of the European Space Agency from the 2020s to the 2050s, and Reaction Engines are now completing the €1 million study announced last August into Skylon’s merits as the Next Generation European Launch System.
Short-term vs long-term views
People with a view on the future in space tend, Mark said, to fall into one of two camps, taking either a short-term or a long-term view.
The short-term perspective is interested in finding a replacement for current space launch systems. Here Skylon offers a fundamental change in space access in two ways: firstly by dropping the price sufficiently that the price charged to satellite operators and space passengers can now cover the costs of development, vehicle construction and maintaining a spaceport, while providing a profit margin as well. This contrasts with the current situation, in which launch vehicles such as Ariane receive hefty government subsidies (in the case of Ariane 5, reported in the German magazine Raumfahrt Concret as between €24 million and over €100 million per launch, presumably depending on what is included – see vol.78, p.5 and p.6).
The second way is that, since it employs an aerodynamic horizontal take off, Skylon has abort capability. At present if a rocket malfunctions the payload is lost in addition to the vehicle; the Skylon philosophy is to recover both vehicle and payload, just as on an aircraft.
Proponents of a long-term perspective, on the other hand, are looking for a game-changer that can realise the dreams of the pioneers of 50 to 100 years ago. Here, too, Skylon offers the technology needed for fulfilling those dreams, by virtue of being designed such that each vehicle can fly up to about twice a week. This makes Skylon “an immensely powerful tool”.
A reusable upper stage is also part of the Skylon system, originally designed for the basic mission of launching a satellite onto a geostationary transfer orbit. Starting from this basis a whole array of other missions open up, including space station construction and servicing, a lunar base, the “Troy” Mars exploration mission, solar power satellite construction, and of course space tourism (details available in reports published on the Reaction Engines website).
The devil in the details
A robust space age needs more than just affordable access to orbit. One other key technical factor is still missing, and that is a universal interface between space satellites and modules, Mark told the meeting.
Satellites are still typically attached to their launch rockets by explosive bolts – not a practice which lends itself to the adoption of reusable launchers. The trick here is to try to persuade operators of the benefits of being able to redock with a satellite already in orbit for refuelling or maintenance.
While the ISS partners have created an international docking standard in manned spaceflight, their current system uses a hatch which is too small to transfer standard station experiment racks from one module to another, and is in any case too heavy and too expensive. It is being ignored by the designers of both Orion and the prospective future Russian replacement for the Soyuz capsule.
There is therefore a critical need for a universal interface which is cheap and light enough to be attractive to spacecraft designers, and is versatile enough to operate in a number of different modes for different purposes (carrying satellites on a launch vehicle, serving as a hatchway on a manned space station, offering when necessary electrical and refuelling links). The Skylon Universal Space Interface Standard (described in the Skylon Users’ Manual) is the proposed solution. But Mark needs independence from Reaction Engines in order to push for this effectively, hence his recent establishment of Hempsell Astronautics as a separate company.
Systems that service satellites need to be able to attach to them, he told the meeting; systems that transport them from one orbit to another need to likewise; as do generic modules for orbital assembly; as do rescue vehicles – not only in space, but when the time comes on the surfaces of the Moon and Mars.
We therefore need a well designed space equivalent of the QWERTY keyboard, or the three-pin plug, or the standard railway gauge: a standard that everybody uses and allows anything to dock to anything: “All applications, for all users, for all time”. Because once a standard exists we’re stuck with that standard forever, so it had better be a good one.
Questions from the audience
What about SpaceX? Mark expressed some skepticism about their low prices: could it be that they had been skimping on essential reliability testing?
When might Skylon first fly? Given appropriate support the spaceplane could be flying by 2022, Mark told the meeting. Since the Americans recently announced an extension to the ISS until 2024, he was still hopeful that Skylon would appear in time to fly resupply missions to the ISS.
I raised the question of whether studies had been done into the rate of growth that might be possible with Skylon. Mark agreed that such studies would be fun to do, but cautioned that they would hardly be accurate: the limits on the growth of such disruptive technologies are difficult to spot. Well, accurate or not, see one sketch of future growth offered in AE issue 99.
For the present, work is now continuing at Reaction Engines on the design and construction of a full demonstration engine.
The momentum which Skylon has acquired over the past few years is enormously encouraging, and we should all hope that after decades of waiting, the project will reach fruition within the next decade.
NB: Mark’s talk was filmed, and the result has been posted on YouTube – unfortunately, the sound quality is very poor.