Suborbital Human Space Flight

In case the terms "orbital" and "suborbital" still causes a bit of confusion read our page Suborbital vs Orbital Space Flight.

What is suborbital space flight? 

From a legal point of view, the discussion in the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) to define suborbital space dates back 40 years or so (related to cold war ballistic missiles, test flights, etc.) an never resulted in agreement until today. The 100 km limit, which has been proposed, has therefore also no legal international binding. From a technical point of view, we most prefer the definition of suborbital space flight to cover all space flight activities, which do not achieve orbital velocities and therefore do not stay in an orbit around Earth. A typical example is sounding rockets. Human suborbital flights to 100 km altitude are very similar and result in a ballistic flight of about 3 minutes duration and re-entry G-loads,  which are sustainable for almost all humans. Although of short duration, the passengers will experience their most exciting minutes in life in seeming weightlessness and a view of Earth, which less than 1000 people have ever experienced since Yuri Gagarin's first human space flight in the year 1961.

How it started

On September 29 and October 4, 2004, the aircraft designer Burt Rutan demonstrated with his rocket plane SpaceShipOne, that a small reusable rocket plane could be designed, built and flown by a small privately funded team of space enthusiasts. This pioneering event did two important things:

  • It showed the large interest of the general public in suborbital human space flights, and
  • It stimulated many followers.  

Current Situation and Main Players 

Today many people are convinced that private suborbital space flight is not only technically feasible but also a very interesting business.  According to an article in "The Economist" on May 11th, 2006,  "more than US$ 1 billion is known to have been committed to building private spaceships and the infrastructure to support them." 

Several companies are currently in midst of a development of a rocket vehicle for suborbital human space flights. Some of the better known companies are:

  • Virgin Galactic, who contracted Burt Rutan to build SpaceShipTwo
  • Rocketplane
  • Blue Origin
  • Space Adventures

Other companies such as XCOR, Amardillo Aerospace, Star Chaser or C & Space have interesting system concepts and component developments, but a funded vehicle development has not yet been publicly announced.

EADS Space Transportation, which introduced their vehicle concept at the Paris Airshow in 2007 has a similar vehicle concept like Rocketplane. The business plan of EADS with vehicle development cost of US$ 1 billion is however puzzling. EADS simply appears too big for this domain and market.

The Future

Many of the announced vehicle development plans appear overly optimistic (first passenger flights in 2008) and delays are very likely. Others are technically extremely challenging and will probably encounter significant technical problems. But some are very credible and it is therefore probable that at least a few of these companies will attain an operational vehicle in a couple of years.

It can be assumed that with the first successful operational flights the public interest will boom and the demand for tickets will strongly increase. The commercial return and the increased confidence of investors will give these companies a powerful leverage to enhance their vehicle designs.

A free global market will generate a healthy competition, which will naturally assure a technical evolution towards:

  • Higher safety - the single most important factor to assure business success
  • Increasing performance and longer flight times - what customers want in the first place 

Bound for Orbital Space Flight

The increase of safety and most of all performance will occur in gradual steps. However as long as a free market exists this gradual evolution is assured as it is the case in all technological domains with a free market.

For this reason there is a strong probability that orbital velocities will be reached one day - though this might take 20 years or more. However at that point not only vehicles for low cost orbital space transportation wil exist, but a new market of will have developed in this process - the market of commercial human space flight. With this perspective sub-orbital space flight is a stepping stone towards low-cost orbital space access - for manned as well as unmanned flights.

In this process, suborbital space flight will also generate a range of low-cost rocket components, because the availability of such components is a precondition for a commercially viable business model. Traditional space flight applications will also benefit from such low-cost components, particularly due to the high reliability which these components will demonstrate through frequent operational flights.


In the last two years suborbital space flight activities gained significant momentum. The general public shows a strong interest in these activities. This underlines the potential size of the market. Most importantly however: Sub-orbital space flight is bound to gradually evolve and it is very likely that orbital space flight capabilities can be reached in the of coarse of a few decades. The consequences of such a low-cost space access in terms of business potential but also in terms of human evolution are probably unmatched by any other commercial activity.


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