Crew Space Transportation System

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The Crew Space Transportation System ( CSTS ), also called Advanced Crew Transportation System ( ACTS ), was a study for a manned spacecraft that was to be jointly developed by Roskosmos and ESA and was finally discontinued in 2009.


The CSTS was known under the name Advanced Crew Transportation System (ACTS) until mid-2006 . A first concept should be available by June 2007. A year later the ESA ministerial conference decided on the actual construction of the CSTS.

With the CSTS it should be possible, similar to the planned US spaceship Orion , to operate in low Earth orbit as well as to carry out flights to the moon . A new development based on the Soyuz spaceship was planned , which was to be carried into space by an existing or planned launch vehicle (e.g. Soyuz 2-3 ).

The Japanese space agency JAXA might also have participated in the project.

At the end of January 2009, disagreements between Roskosmos and ESA became public. On March 18, 2009, the contracting parties made a joint declaration that the program had ended. The reason given was that it was not possible to reconcile Moscow's financial ideas with Europe's interests in an equal partnership. Roskosmos initially developed the project further under the PPTS . Later it became a "manned transport ship of the new generation" (PTK NP), which was finally named Orel (Adler).


Russian project Kliper

In January 2004, US President Bush announced his " Vision for Space Exploration ". Among other things, the program stipulated that the United States of America should again carry out manned flights to the moon from 2020 and also manned flights to Mars from 2030.

However , in 2006 , NASA administrator Michael Griffin officially rejected international collaboration on the Orion spacecraft, which was being developed for this purpose .

Since 2004, Roskosmos had been planning a successor to the Soyuz spaceship named Kliper . Despite the positive attitude of the ESA management, the ESA ministerial conference in Berlin in 2005 refused to participate in Kliper, out of concern that ESA could only play a minor role in the development. The tender for Kliper was also closed by the Russian side without an award in the summer of 2006, officially on the grounds that no proposal had met the criteria.

The study

Announcement of the study

On July 25, 2006, ESA Director Jean-Jacques Dordain announced at the Farnborough Air Show that the study of the CSTS would begin in early September 2006 and last about 18 months (through early 2008). The costs for the ESA for the study amounted to 15 million euros, which were raised by seven European countries, including Germany, France and Italy. The budget of the Russian side was not disclosed.


ESA had announced several times that the study on its own spaceship system should not represent a program in competition with the US Orion spaceship, but Marco Caporicci, team member in the manned ESA program, had made it clear:

"We don't want a race with the Americans, the systems should rather complement each other."

On the other hand, Daniel Sacotte, Director of Human Spaceflight at ESA, had said about ESA's goals:

“We will try not to let our dependence on other partners become too strong. That is our priority. "

Manuel Valls, ESA strategist with reference to the manned spaceflight of ESA, added this statement with reference to the Russian cooperation:

"Our long-term goal is to develop and operate this new system together with the Russians."

The finished ship was to be "jointly owned" by Russians and Europeans.

Sub-areas of the study

According to a statement by Jean-Jacques Dordain, the sub-areas of the study included:

  • Basic design of the system
  • Detailed design of the subsystems including a coupling mechanism
  • Decisions about the division of labor in a full development
  • Manned moon flights

Preliminary design for a spaceship

Soyuz variant

The structure of the CSTS should be similar to that of the Soyuz spaceships

According to the media, the core of CSTS should be a spaceship based on the basic principle of the Soyuz spaceship . It should have storage space for more supplies for longer missions, an improved heat shield for a higher re-entry speed into the earth's atmosphere, a new interplanetary navigation system and space for a crew of three or four. The mission should last at least 18 days. The empty weight would have been at least 10 t (Soyuz-TMA: 7.2 t), especially due to the longer mission duration and the enlargement for four people.

The CSTS spaceship, like the Soyuz spaceship, should consist of three parts:

  • An enlarged living module that houses supplies and life support systems. Both Russian and European technology developed for the International Space Station (ISS) should be able to be used. Since the orbital module should not have a heat shield, enough space for equipment, life support systems for longer missions and crew could be made available with little weight gain. According to Russian information, the residential module was to be developed by ESA.
  • The service module should contain the technology for navigation (e.g. engines), communication and power generation (solar cells). With the service module, the weight is determined in particular by the fuel. The more acceleration the CSTS spaceship should contribute to moon missions, for example, the heavier this module would be. In the US Orion, around 60% of the mass is accounted for by the service module with fuel. Due to the modularity of the concept, a fourth or even fifth module could have been used for lunar flights for the necessary thrusts into the lunar orbit, within the lunar orbit and out of the lunar orbit. Both ESA and Roskosmos would have wanted to build the service module.
  • Before re-entering the earth's atmosphere, the living and service modules should be disconnected. Only the return module would have landed safely on earth with the space travelers . The bell shape of the Soyuz landing capsule was considered likely, as a new development would have cost additional time and money. The mass of the return module would have been at least 3 t, since the Soyuz lander for three crew members already weighs 2.9 t.

Advantages of a three-part concept compared to the two-part CEV or Apollo concept:

  • Simplified and cheaper production of the living and service modules that do not have to survive re-entry. The lighter construction saves critical weight in particular for moon flights.
  • The landing capsule can thus remain at the minimum weight, which u. a. allows a higher re-entry speed.
  • The CSTS concept offers the flexibility to build optimized versions of living and service modules for the respective mission types.

Other variants

According to an ESA working paper on the status of the European strategic program for space exploration dated September 12, 2006, the CSTS study also dealt with other variants, such as lifting body concepts , in which the missile itself generates lift, and so-called "advanced" capsules ”, ie re-entry capsules with new external dimensions.


The most likely launch vehicle for the approximately ten-ton CSTS spacecraft was a further development of the Russian Soyuz rocket . From 2010 Soyuz rockets should be able to be launched from Baikonur in Kazakhstan as well as from the Kourou spaceport . Manuel Valls (ESA) was hoping for the construction of the Soyuz-2-3, a further development of the Soyuz rocket, which will be available from 2010/2011 and could launch eleven tons from Baikonur and 12.7 tons from Kourou. The use of so-called "heavy lifters" such as Ariane 5 or Proton , however, was not considered, as these are not approved for manned space flight and would therefore incur additional costs.

A flight to the moon would add at least 115% (if a stage with liquid hydrogen and liquid oxygen (LH2 / LOX) were used) of the mass of the CSTS spaceship for a moon flight module (earth departure stage). This module should accelerate the spacecraft to the escape speed required for a moon flight . After that, the CSTS spaceship would have to carry out all further acceleration thrusts or course corrections itself. In addition, the need for supplies (food, water, oxygen, etc.) would increase.

Since neither ESA nor Roskosmos wanted to raise the necessary funds for a new heavy-duty rocket the size of a Saturn V , an Ares V or an Energija , it made sense to split the CSTS into two or more rocket launches and to couple the parts in Earth orbit.


Since the CSTS program has now ended, the following mission scenarios remained pure planning.

CSTS spaceship LEO missions

A CSTS spaceship should be used in 2012 or, according to other press articles, in 2014 as the first functional version of the CSTS for LEO flights (e.g. to the ISS). ESA's (preliminary) planning for a manned lunar mission as part of the Aurora program, however, assumed a possible start between 2020 and 2025.

Moon flyby

A further developed version of the CSTS should enable both manned lunar flights, in which the moon is circled only once and no stable lunar orbit (LLO) is reached, as well as manned lunar flights, in which a stable lunar orbit is achieved.

In a variant, the CSTS would take off from Kourou or Baikonur and dock with the ISS. The space travelers will remain on the ISS until an additional stage of propulsion is launched into earth orbit. The CSTS spaceship would then disconnect from the ISS and connect to the propulsion stage before it accelerates the system into a lunar transfer orbit.

Moon landing

A manned moon landing would be different from a moon flyby, as the CSTS spacecraft would have to enter lunar orbit and leave it again at the end of the mission, which requires more fuel. In addition, at least a third rocket launch for a moon landing module would be required.

See also

Web links

Individual evidence

  1. a b c Spiegel: Europe and Russia are planning their counter-shuttle
  2. FliegerRevue June 2010, pp. 54–59, Russia's new spaceship
  3. Проект нового космического корабля "Федерация" получит название "Орел" . TASS, September 6, 2019.
  4. russianspaceweb: Advanced Crew Transportation System (English)
  5. ESA, Human Spaceflight, Microgravity and Exploration Program Board (English) ( Memento from September 27, 2007 in the Internet Archive ) (PDF; 2.7 MB)