Friday , November 27 2020

20 years since Russia hurled the first bit of floating astronaut hostel into the orbit • The Register



No one fancied Salyut-style to the Mir to grab some gear

Zarya

Well, that's not a bit of Mir. It's the first part of the ISS (credit: NASA)

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 November 20, 1998, signifying the start of ISS assembly. Also known as "Zarya" (Russian) in reference to Russia's first space station in 1971, the module, which was built for the still-orbit Mir, was designed to provide power, storage and propulsion during early stages of ISS assembly.

Construction

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 been disabled, and solar arrays to provide power. These arrays were subsequently retracted to allow radiators on the US truss segment to be deployed later in the ISS assembly.

The module was 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 be 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 to the last minute, according to James Oberg in his book Star-Crossed Orbits, negotiations continued between the largest contributors to the ISS, the USA and Russia, on the actual orbit of Zarya. One school of thought felt that placing 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 and between the 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 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 program. An ambitious assembly sequence was planned and a Space Shuttle mission was set to launch the first US contribution to the ISS in the form of the Unity module.

Launch

The launch almost ended in disaster. A flaw in the design of the module almost stopped the ISS program dead in its tracks as the FGB reached orbit and then ignored commands from the ground.

The FGB would simply return to Earth as its orbit decayed, burning up in the atmosphere, and if the situation was not resolved within days, the FGB would simply return to Earth.

NASA was, of course, blissfully unaware of the unfolding crisis and the Americans lacked any kind of independent control and monitoring abilities for the Russian side.

Fortunately, and 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.

Unity

NASA sent up a Space Shuttle and few weeks after the launch of the FGB to attach the Unity module from which US and other ISS partners could hang their own contributions to the program. December's STS-88 was followed by STS-96 in May 1999 and STS-101 in May 2000, with 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 program. 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 its desire to end funding by 2025, effectively killing off the ISS. NASA hopes that the private industry could plug the gap, but as its modules continue to increase the chance of the station getting much over a quarter of a century seem remote. ®

Bootnote

As if to emphasize the age of the ISS, the current crew member Alexander Gerst opened up one of the lockers onboard and pulled out … a bunch of Save icons? He did not elaborate on whether retro-storage could still be used.

Thanks to the Register reader who pointed to us at this tweet.


Source link