Tim Furniss/LONDON
After a tortuous political and financial gestation period, the International Space Station (ISS) is only one year away from reality. In November 1997, a Russian Proton booster will launch the first element of the space station, called the Functional Energy Block (FGB). A month later, the US Space Shuttle, the Endeavour STS88, will add a Node 1 connection module to the FGB.
In April 1988, Russia will, it is hoped, respond with the launch of the Service Module. A month later, the first Space Station expedition commander, US astronaut William Shepherd, will be launched - in the passenger seat of a Russian Soyuz TM. The choice of three-time Shuttle veteran Shepherd as commander of what will be, at this stage, a largely Russian space station, is controversial. Soyuz commander Anatoli Solovyov has been designated Space Station module commander in an attempt to mollify the Russians.
veteran cosmonauts
Solovyov will be accompanied by flight engineer Sergei Krikalev. Both Russians are veterans of Space Shuttle missions during the ISS Phase 1 programme involving flights by Russian cosmonauts on the Shuttle. Shuttle flights will dock with the Russian Mir 1 station and visits by US astronauts on the Mir will continue into 1997, with three more planned Shuttle Mir Missions. These will involve joint US/Russian space walks and the deployment of a US/Russian solar dynamic electrical generator, which will be tested for possible use at a later stage of the ISS.
A replacement US-Russian crew may arrive aboard another Soyuz TM later in the year. Both nations will continue the assembly of the station with Shuttle and Proton flights. Larger crews will work on the station for up to 14 days while the Shuttle is docked to it. The Shuttle and a Soyuz TM will require assured Earth-return capability.
Canada's robotic manipulator system will be an early arrival, and the US Laboratory Module will dock in November 1998. With the first Space Shuttle station utilisation flight in February 1999, the ISS Phase 2 will be completed. Phase 3 flights will complete the construction in 2002, with Japanese and European modules, a second Soyuz TM emergency return craft and other equipment. Over 80 walks, primarily by US astronauts, will have been required during the assembly.
The ISS will include 46,200ft3 (1,631m3) of work and living space, and generate 11kW of electricity from its two 112 x 39ft (35 x 11m) solar arrays and a 115m-long truss. It will consist of seven laboratories and a habitation area, plus solar arrays, robot arms and other equipment. It will then be permanently manned by six people, consisting of international crews from Canada, Japan, Russia and the USA, and probably from other countries. Future commanders of typical 90-day Space Station shifts may be Russian or from other nations, decided by an international committee.
Uncertainty over schedule
As with everything involved in the project, however, this schedule is still in doubt. Delays are looming and, although financially assured - at least in the USA - the ISS schedule and the project itself still depends too much on the Shuttle. Conversely, the Shuttle's existence will be justified only by its station work. Seven of the eight Shuttle flights each in 1999 and 2000 will be Space Station missions, several of them, utilisation flights to deliver payload racks. Two of the 1999 space utilisation missions will also include scientific operations, on US Congressional insistence and much to NASA's chagrin. All seven Shuttle missions manifested for 2001 are station-related.
The building-block approach to the station forced on NASA is open to schedule problems. A Saturn 5 launching two or three Skylab-type modules would have been a solution, but the Apollo's Saturn 5 booster was scrapped in 1973 and even the rockets drawings thrown away.
There will be four Russian assembly flights in 1999 and three in 2000. Russia, however, will be supporting the assembly with a fleet of Soyuz-launched Progress tanker flights for orbit re-boost. Over 70 launches, will be required by the USA and Russia to complete the station, 19 of which will be re-boost missions.
Later, Russia proposes the use of FGB-type propellant tankers, called Logistics Transfer Vehicles (LTVs) launched on Protons to reboost the station in the later stages. If funding difficulties make it impossible for Russia to build the LTVs, more Progress tanker flights will have to be added.
It is estimated that the Space Station will need about 120,000kg of propellant for maintaining its 300 x 365km orbital altitude during the first decade of operations. Russia will also supply Soyuz TMs for additional crew ferrying and for assured return. Two TMs will have to be docked permanently after operational capability is reached, to provide quick escape for six crew. An experienced Russian flight crew will therefore always need to be part of the crew shift.
Although Russian participation saved the Space Station in the US Congress, financial and political difficulties in that country must also cast doubt on the realism of its commitment and to the station assembly schedule.
Russia is being given a one-off payment of $200 million for the FGB. Other elements will come from its national finances (not from NASA or US contractors) and the programme seems on schedule after earlier worries. The Russian habitable Service Module, however, is behind schedule, reportedly by several months and lacks 90% of the Government finance necessary to complete it.
Critical Khrunichev/Energia
This Khrunichev/Energia-built module is critical, to allow manning to begin, and to allow more modules to be added. The Shepherd-crew occupation could be delayed significantly. A more serious delay could mean NASA expelling Russia from the programme and hastily building its own service module, delaying the project by two years. This would have a near-critical knock-on effect on the schedule and budget, and on the ISS' already-frustrated partners.
Alternatively, the module may be launched closer to its scheduled date, but will have to be outfitted in orbit by the first crew. Later planned Russian modules are also behind schedule. The Russian Government is under intense pressure from NASA and higher Government circles to deliver the money to contractors to allow the schedule to be met. November 1996 is considered to be a crucial time for the programme as, by then, Russia should have completed the mechanical assembly of the Service Module.
All the while, the Japanese Experiment Module (JEM) and Europe's Columbus Orbital Facility (COF) will be delayed further. Today's schedule has the JEM in place by 2001 and the COF by 2002. Even this will be without its centrifuge for biological research, which will be delivered after the station has been completed.
The schedule for the original Space Station Freedom, was for completion to be reached in 1994, ten years after President Ronald Reagan gave it the go-ahead. NASA's inter-nationalisation of the station was the only attraction to Reagan, whose commitment did not have the political or financial backbone of Kennedy's Apollo decision.
PRESIDENT CLINTON'S SUPPORT
The station - costing $17.4 billion - has been redesigned and down-scaled many times to ensure its financial survival and the project has been fortunate to have had such a keen supporter as President Bill Clinton and a realistically enthusiastic NASA administrator in Daniel Goldin. Together, they have established a constant $2.1 billion-a-year funding package to the station to 2002.
The Boeing-led US station has not escaped technical or financial difficulties either. The Node 1 has experienced problems and the station could already be $500 million over-budget by 2002, says the US General Accounting Office (GAO). This could be reduced to $180 million, by dipping into NASA's annual portion of a total $2.9 billion reserve built into the station budget structure. The GAO warns that this reserve could be eaten into prematurely as a result of underestimates and poor contractor performance, already experienced in the form of faulty software and the late delivery of components.
The Node 1 failed 22.8 psi pressurisation tests (at 1.5 times normal operating pressure) and had to be strengthened by the addition of eight bracing struts on each of the connecting points to redistribute pressure. In addition, engineers felt it necessary to strengthen the Node against the forces imparted throughout the structure during the "dynamic" docking of new modules. The Node is one of two docking ports, which will be placed on the station to provide a total of 12 potential connection points. Only two will be used on the Node 1, however.
The problems with the Node 1, caused by many years of design changes, delayed its launch by six months but the design and building of the flight elements for the first six US Space Shuttle assembly missions are well under way and it seems that, at last, the station is "go".
The completed International Space Station in 2002
Source: Flight International
