Building on sand?
The Russian segment of the International Space Station (ISS) will further grow with the addition of the Mini Research Module-2 (MIM-2) that was successfully launched aboard Soyuz-U launcher in November. The new component will provide the docking of a second Soyuz-TMA spacecraft, which is critical to maintaining an expanded permanent crew at the station. During the next few years Russia will keep building up the capabilities of its ISS segment so that it could eventually continue fully autonomous orbital operations, if so required.
The ISS is the largest space exploration project ever. It is a joint effort of Russia, the USA, Japan, Canada and member nations of the ESA European Space Agency. The initial ISS configuration was agreed in 1996, when it was decided that the station would consist of the Russian and US segments (the latter one with the participation of Canada, Japan, Italy and the ESA member nations). The ISS was to orbit the Earth at an altitude of about 400 km, with an inclination of 51.6 degrees.
Compromising for success
The orbit parameters were a substantial compromise: they cost the USA an ability to service its in-orbit satellites — something NASA was initially planning for, — while simultaneously depriving Russia of an opportunity to monitor a significant portion of its own territory (which would have been secured with Moscow’s original plan for an orbit inclination of 65 degrees). The exact overall cost of building and operating the ISS is unknown, but our estimate is that the price tag stands at some $150 billion, since the USA alone has so far spent at least $100 billion on the program – including the cost of sending the space shuttles to the station.
As of mid-October 2009, America’s ISS segment included the following major modules: the US-made Destiny, Quest, Unity (Node 1) and Harmony (Node 2); ESA’s Columbus, and Japan’s Kibo. At print time, the Japanese HTV H-II Transfer Vehicle was docked to the Harmony node. The Russian segment currently comprises the Zarya Control Module, Zvezda Service Module and Pirs Docking Compartment.
Zarya, also known by the name of Functional Cargo Block or by its Russian abbreviation FGB, was the first element of both the Russian segment and the entire ISS. Orbited on 20 November 1998, it became the growth point of the station. Zarya was built by the Khrunichev Space Center as a derivative of an earlier cancelled program. Ironically, since Zarya was built at the US request and the major portion of the development funding for the module (some $250 million) came from the USA, it is formally referred to as a component of the US ISS segment. And yet Zarya remains part of the Russian segment because of the Russian-made equipment it accommodates. The FGB’s primary functions were to provide for the station’s initial attitude control and propulsion. Apart from that, prior to its mating with Unity and Zvezda, Zarya provided limited power supply to the entire installation. Weighing in at over 20 tons and measuring 12.55 meters in length, the module is now also valued for the all-important storage capacity it provides, as well as for other operational capabilities. Its design service life spans at least 15 years.
The Zvezda module was launched on 12 July 2000 to provide living quarters for the Russian segment. At the beginning of ISS construction, it served as the life support system for the entire station and was also available for flight control and propulsion operations. Zvezda was used as the docking port for Progress-type cargo resupply vehicles. It also provided a communications link with the Earth and doubled as the ISS computing center. The module has a mass of 19.05 tons, measures 13.1 meters in length, and is equipped with four docking ports. Like Zarya, it was built by Khrunichev.
The Pirs Docking Compartment is intended as an additional docking portal for Soyuz-TMA and Progress craft. Apart from that, it is also used as an airlock for Russian cosmonauts’ extravehicular activities. The module weighs some 3.6 tons and has a length of 4.91 m. It was built by the Energia Rocket and Space Corporation and was launched on 15 September 2001.
For quite some time the development of the Russian ISS segment was impeded by a variety of factors. The hardest blow to the assembly progress was dealt by the Shuttle Columbia disaster on 1 February 2003, in the wake of which the entire budget of the Russian manned space program got steered towards providing crew relief missions on board Soyuz-TMA vehicles and cargo resupply flights by Progress craft. Financial difficulties were also never far away from the ISS — the Russian funding did not fall into a comfortable pace with the program needs until the mid-2000s.
Looking into the future
Despite these difficulties, Russia has continued working to expand the ISS. The global economic crisis notwithstanding, the financial problems have been largely solved, and the current target of the year 2015 or 2016 as the completion date for the Russian segment does not look all that fantastic. The MIM-2 research module was launched on November 10, 2009 from Baikonur Cosmodrome. This module is based on a Progress spacecraft design, and its primary role will be in providing the docking opportunity for an extra Soyuz-TMA craft. This is essential because the permanent ISS crew was expanded from three to six people earlier this year. This means that at any given time the station must have two Soyuz-TMAs docked to provide a rescue capability in case of emergency. MIM-2 will dock Zvezda’s space-facing port. The module weighs some 4 tons, including one ton of instrumentation to be used on the station.
In the spring of 2010, space shuttle mission STS-132 will deliver to the ISS another small-size research module - MIM-1. This one is being built at NASA’s request. It will have a total mass of just under 8 tons, including 3.2 tons of cargo for the station — of this figure, 1.4 tons will be destined specifically for the US segment. The MIM-1 design is based on the as-yet-nonexistent Russian Science Power Module (NEM). Apart from the cargo for the ISS it will be used as a docking module. It will dock to Zarya’s Earth-facing docking node, and will accommodate both Soyuz-TMA and Progress-M vehicles. The lower section of MIM-1 houses components that will eventually be moved to Russia’s prospective Multipurpose Laboratory Module (MLM). These include a portable airlock and a spare elbow joint for the European Robotic Arm manipulator, and a transferable workplace with an ERA mounting platform.
The MLM has a mass of 21 tons. It will be one of the largest Russian modules at the ISS. Scheduled for lift-off in 2011, this module will serve as the new center of the Russian segment. It is planned to be used for major scientific experiments. The MLM design is based on the concept of replaceable payloads, which turns it into a top-class multirole science laboratory.
In order to expand the functional capabilities of the Russian segment, The Universal Docking Module (UDM) with six docking ports is to be delivered to the station in 2013. It will use one of those ports to dock to the MLM. The UDM will be used to accommodate the two Science Power Modules (NEM-1 and NEM-3), as will provide extra docking opportunities for Soyuz and Progress craft.
The Russian segment will be complete after the two NEM modules are delivered. NEM-1 will go up in 2014, to be followed by NEM-2 a year later. These modules will accommodate additional scientific equipment and will increase the Russian segment’s power output by at least 72 kW. Each of the NEM modules weighs about 20 tons and is fitted with large-area solar arrays.
The completion of the Russian segment will boost the effectiveness of ISS-based scientific experiments, which has repeatedly drawn criticized over the past few years. At present the Russian segment is used for a variety of experiments as part of a long-term applied research program approved in 1999. Many of them are conducted by Russian cosmonauts in the interests of foreign customers. The situation is sure to change after the MLM becomes part of the Russian segment and enables Russia to conduct fundamental and applied research and create materials with unique properties.
The most important question for the ISS, however, is whether it will be able to go on for much longer. The key existing agreements between the program participants expire in 2016. The USA has repeatedly stated that it was not planning to keep using the station beyond that date. Washington’s position jeopardizes the entire program, as Russia and Europe would like for the ISS to continue through 2020. Recently, after Barack Obama became president, the US administration has somewhat backed up on the issue. It would appear that, having encountered technical and financial problems in its own Constellation human spaceflight program, Washington decided after all to stick with the ISS.
In Russia’s case the ISS creates a very much specific problem that rarely gets mentioned. Up to 50% of the country’s space budget is spent on the manned space program (the other space powers spend much lesser proportions of their overall budgets on maintaining human presence in orbit). Such massive spending precludes appropriate development of other aspects of space exploration. On the other hand, the ISS once rescued Russia’s space industry by keeping it busy through the difficult mid-1990s and early 2000s. Besides, Russia cannot just dump one of its priorities — long-period manned space flights. This is why the Russian segment is being built in such a way as to continue operating autonomously, as the national orbital station, if the Western partners choose to walk out on the program.