The International Space Station turned 20 this week as space agencies and 'nauts alike celebrated the anniversary of the launch of the first module of the ISS.
The Functional Cargo Block (FGB) was launched on 20 November, 1998, signifying the start of ISS assembly. Also known as "Zarya" ("Dawn" in Russian) in reference to Russia's first space station in 1971, the module, which had been built for the still-orbiting Mir, was designed to provide power, storage and propulsion during the early stages of ISS assembly.
Russia kicked off the construction of the 19,323kg (42,600lb) FGB in 1994, with the US contributing $220m. It is 12.56m long and 4.11m across at its widest point and is primarily used for storage. The module enjoyed its own thrusters, which have long since been disabled, and solar arrays to provide power. Those arrays were subsequently retracted to allow radiators on the US truss segment to be deployed later in ISS assembly.
The module was only designed to fly autonomously for a few months, but ended up waiting until July 2000 before the hugely delayed Zvezda service module arrived to allow continuous habitation to begin later that year.
Worryingly, the FGB also only had a 15-year service life at launch, though Russian engineers reckon the venerable module is good until 2028 following ground tests, double its original lifespan. Replacing it would certainly present a challenge. NASA, of course, faces similar difficulties with US modules, such as Unity, which followed the FGB into orbit less than a month later.
Shades of Mir
The FGB had a tortuous path to the launchpad. Right up until the last minute, according to James Oberg in his book Star-Crossed Orbits, negotiations continued between the biggest contributors to the ISS, the USA and Russia, on the actual orbit of Zarya. One school of thought felt that by placing the ISS in the same plane as Mir, Russia could transfer some supplies and equipment from the ageing station. It had, after all, been done before on a jaunt between Mir and Salyut 7 back in 1986.
Maybe even one or more of the existing Mir modules could be hooked up to the ISS (the actual early living quarters for the ISS were running horrendously behind schedule) saving the expense of actually building the things.
NASA, unsurprisingly, flatly refused, despite the agency's desperation to get something into orbit after the billions that had been poured into its space station programme. An ambitious assembly sequence was planned and a Space Shuttle mission was standing by to launch the first US contribution to the ISS in the form of the Unity module.
The launch nearly ended in disaster. A flaw in the design of the module nearly stopped the ISS programme dead in its tracks as the FGB reached orbit and then, er, ignored commands from the ground.
Instructions to the uncrewed module to raise its orbit went unanswered and if the situation was not resolved within days, the FGB would simply return to Earth as its orbit decayed, burning up in the atmosphere.
NASA was, of course, blissfully unaware of the unfolding crisis (it would be some time before the full picture was communicated to the agency) and the Americans lacked any kind of independent control and monitoring abilities for the Russian side.
Fortunately, a Lieutenant Colonel called Nazarov, who had trained on FGB-class vehicles and their failure modes, was able to sketch out some alternative command codes and, in a very real sense, saved the day as the engines of the FGB fired up and lifted the FGB to a higher orbit.
NASA sent up a Space Shuttle a few weeks after the launch of the FGB to attach the Unity module from which the US and other ISS partners could hang their own contributions to the programme. December's STS-88 was followed by STS-96 in May 1999 and STS-101 in May 2000 as NASA outfitted the complex and boosted its orbit while the module awaited the service module.
Zarya required almost immediate maintenance by the visiting crews, with ongoing repairs being somewhat of a hallmark of the ISS programme. Noisy fans and poor circulation left early Shuttle crews, such as STS-96, decidedly queasy as the space agencies learned how to manage their new toy.
As the ISS turns 20, its future remains as uncertain as it did at launch. The current US administration has expressed a desire to end funding by 2025, effectively killing off the ISS. NASA hopes that private industry could plug the gap, but as its modules continue to age the chances of the station getting much past a quarter of a century seem remote. ®
As if to emphasis the age of the ISS, current crew member Alexander Gerst opened up one of the lockers onboard and pulled out... a bunch of Save icons? He did not elaborate as to whether the retro-storage could still actually be used.
I found a locker on the @Space_Station that probably hasn't been opened for a while... / Ich habe hier auf der #ISS ein Fach gefunden, das vermutlich schon seit einer Weile nicht mehr geöffnet wurde... #SpaceStation20th pic.twitter.com/XOc3FS8tMm— Alexander Gerst (@Astro_Alex) November 20, 2018
Thanks to the Register reader who pointed us at this tweet.