International Space Station:
Hi and welcome to Failurology; a podcast about engineering failures. I’m your host, Nicole, and I’m from Calgary, Alberta.
It's episode 10! Double digits baby! And I have something special planned. Full disclosure, as something special for episode 10, I had set out to tell you about an engineering marvel, and I still will, but when I started researching, I found all of these smaller failures that I thought you’d want to know about too. With that said, this week’s episode is about the International Space Station. Now, I don’t think any failures or issues are due to engineering mis-steps or oversight. We have barely scratched the surface of space exploration, and all things considered, the International Space Station is an extremely impressive human accomplishment. But things still go wrong. Especially after 22 years in space. Yes, that’s right. Did you know it’s that old?!? Boy, how time flies. But first, the news.
Houston, this is Failurology, ready for take off.
This week in engineering news; transparent solar panels.
A study from Incheon (in-chon) National University in South Korea demonstrates the practicality of transparent solar cells. Researchers used a glass substrate with a metal oxide electrode, thin layers of semiconductors, and a coating of silver nanowires. The semiconductors were made from titanium dioxide, an environmentally friendly and non-toxic material, and nickel oxide, nickel being an abundant element on earth that is able to be manufactured into nickel oxide at low temperatures. Both semi conductors have a high optical transparency; meaning they can absorb UV light while allowing most of the visible light through.
The solar cell had a power conversion efficiency range of 2.1%. Are you thinking 2.1% is low? So did I. But the world record for maximum power conversion efficiency is 22.49%. with that in mind, 2.1% on the first crack at something that hasn’t been done before seems pretty good. And the solar cell still allowed more than 57% of the visible light through the cell.
The applications for this research and the advancements that will come from it are endless. Commercial and residential building windows or exteriors, car exteriors, even phone screens. This is just the beginning.
If you want to read more on the study, check out the podcast page for this episode, link in show notes.
Now on to this week’s episode; the engineering marvels and incidents of the International Space Station.
The international space station launched on Nov 20, 1998; over 22 years ago. It’s currently expected to remain in operation until 2030.
The station is 73m long, 109 m wide, weighs 419,725kg, and has a pressurized volume of 915.6m3
Atmospheric pressure – 101.3 kpa – 21% oxygen, 79% nitrogen
With an orbital speed of 7.66 km/s, it orbits the earth in 92.68 minutes, and completes 15.54 orbits per day. The international space station isn’t the first manned earth orbiting station, it’s the ninth.
It was constructed and operates in collaboration with space agencies from the US, Russia, Japan, Europe and Canada
The station has been manned since Nov 2, 2000, with a crew of up to 7.
Over 239 astronauts, cosmonauts, and space tourists from 19 nations have visited the space station. Eight of them were Canadian
To mitigate the loss of muscle and bone mass, astronauts work out for at least 2 hours a day.
And with the onboard water recovery system, the crew dependence on water is reduced by about 65%.
The station’s laboratories act as a microgravity and space environment research lab in astrobiology, astronomy, meteorology, physics and other fields.
It also tests spacecraft systems and equipment for future long duration missions to the moon and mars.
The station is modular, allowing sections to be added or removed. And operates as two main segments; Russian and everyone else.
From the Russian Orbital Segment we have the following modules.
Zarya – which is a functional Cargo Block. It was the first module to be launched, and it provided power, storage, propulsion and guidance during the initial assembly. Now its mostly used for storage
Zveda – the third module launched, that docked on July 26, 2000, provides all of the life support systems (although some are supplemented in the US segment), and living quarters for two. It acts as the centre of Russian segment with crews using this area to meet during emergencies
Pirs and Poisk – identical airlock modules, each with two identical hatches. Their outermost docking port allows docking of Soyuz and Progress spacecraft, and automatic transfer of propellants to and from storage
Pirs was launched on September 14th 2001 and is used to store, service and refurbish Russian Orlan spacesuits and provide a contingency entry for Americans
Poisk – launched Nov 10, 2009
Rassvet – Dockinis the mini research module, used for cargo storage, and a docking port for visiting spacecraft, it was connected to the station on May 18, 2010
In what they refer to as the United States Orbital Segment, which is operated by many nations, there is
Unity – the first US module and the second ever module. It’s the connecting module between US and Russian segments – where crews eat meals together. Unity has 6 berthing locations to connect other modules
Connected to Unity is the Destiny module, launched on February 7, 2001, it's the primary facility for US labs, the research from this facility is used by scientists around the world working in medicine, engineering, biotechnology, physics, materials science, and earth science
Quest which launched on July 14, 2001 is the primary airlock, hosting spacewalks with Extravehicular Mobility Unit spacesuits US) and Orlan spacesuits (Russian), before then Russia used the Zvezda module and US used a docked space shuttle when accessible for spacewalks
Harmony – is the utility hub which connects laboratory modules for US, European and Japanese labs, it provides electrical power and electronic data, sleeping cabin for four crew, when it was launched on Oct 23, 2007 it added almost 20% to the stations living volume, and rendered the US core complete
Tranquility – contains environmental control systems, life support systems, a toilet, exercise equipment, and dome observatory and it launched Feb 8, 2010
Columbus –is the European laboratory which launched Feb 7, 2008
Kibo is the Japanese laboratory and the largest single module
Leonardo – installed on March 1, 2011, is used for central storage of spares, supplies and waste, as well as a personal hygiene area for astronauts in the US segment,
And then there’s my favourite, the Canadarm2 – its 17.6m long when fully extended, seven motorized joints, two end-effectors or hands, 35cm diameter titanium with Kevlar fabric cladding, capable of handling payloads up to 116,000 kg, and can assist with docking, self relocatable and can move to any power data grapple fixture on the station,
There's also 12 solar arrays, two heat radiators, and a number of other components that serve the station and its guests.
With all of the stations and docking segments, eight spaceships can be connected to the station at one time.
There have been 64 expeditions to the International Space Station to date, the latest of which, the SpaceX Dragon launched on Dec 6th 2020, arriving at the station just over 24 hours later. It undocked from the station this past Tuesday Jan 12th at 7:05am mountain time. It was supposed to undock on Monday, but due to unpleasant weather off the coast of Florida, it was delayed a day. It landed Wednesday night at 6:26pm mountain time via parachute-assisted splashdown In the Atlantic with almost 2000 kgs of scientific experiments and other cargo. The landing location allows for quick transport of the research to Kennedy Space Center’s Space Station Processing Facility. Some of the precious cargo the Dragon is bringing back are as follows
Using 3D engineered heart tissue, Cardinal Heart studies the impact of gravity on cardiovascular cells and tissues. From this study, researchers are hoping to better understand heart problems on earth, identify new treatments and improved screening measures to foresee cardiovascular issues prior to spaceflight.
Space Organogenesis, a Japanese program, is studying 3D cell growth using microgravity; whereas on earth they require support to expand into three dimensions. From this study, scientists are hoping to demonstrate how microgravity can be used for developments in regenerative medicine and creation of artificial organs.
The Sextant Navigation experiment tested specific techniques for emergency navigation on deep space mission spacecraft. Sextant has been used by sailors for centuries for navigation.
Scientists studied the function of arteries, veins and lymphatic structures in the eye and changes in the retina of mice before and after spaceflight. 40% of astronauts experience vision impairment on long spaceflights.
A thermal amine scrubber, which contains actively heated and cooled amine beds to remove carbon dioxide from the air onboard. CO2 build up can lead to fatigue, headache, breathing difficulties, strained eyes and itchy skin.
And lastly, an investigation into the growth of biofilm and their ability to corrode stainless steel, as well as the effectiveness of silver-based disinfectant, hopes to provide better ways to control and remove resistant biofilms for successful future long spaceflights.
Now onto the issues, what you all really came here for. The international space station definitely has redundant systems, but there really is no backup per se. You have to troubleshoot and repair everything yourself for the most part. Yes, there are spare parts and ground crews that can help, but they can’t overnight supplies or call a repairman for you. Have you ever tried to fix something and had to go to the hardware store multiple times? It's always embarrassing when this happens, but I think most of us have been there. But there is no hardware store in space….
Now, with that said, here are some of the quote/unquote “highlights” of the system failures on the International Space Station.
2003 Waste accumulation after the Columbia disaster
Space shuttle Columbia disintegrated upon atmosphere re-entry on Feb 1, 2003
Resulted in 2.5 years suspension of the US Space shuttle program, and then another year after the “return to flight” mission due to uncertainty in the future of the space program. During this time, crew exchanges were done using a Russian Soyuz spacecraft. Because the International Space Station was not visited by US spacecraft for over three years, there was more waste accumulated than expected.
2004 Air Leak and Elektron Oxygen Generator Failure
A minor leak was detected on Jan 2, 2004. At its max, the leak resulted in 2.5kg per day of air leaking into space and the internal pressure dropped from 101.3kpa to 96.5kpa.
The astronauts on board traced the leak on Jan 10th to a vacuum jumper hose on a multi paned window in the US segment. And was repaired
The Elektron oxygen generator unit shut down due to unknown causes. Two weeks of troubleshooting got it up and running, but then it immediately shut down again. Eventually they figured out that the cause was air bubbles in the unit, which was not functional until a resupply mission in Oct 2004. It failed again on Jan 1, 2005.
2006 Venting of gas
On sept 18, 2006 fumes from one of three Elektron oxygen generators in the Russian segment activated a smoke alarm. The fumes were later determined to be a potassium hydroxide leak from an oxygen vent.
The station's ventilation system was shut down to prevent potentially spreading smoke or other contaminants to the rest of the complex. A charcoal filter was used to scrub the air.
The Elektron was repaired on Nov 2, 2006 with spare parts from a Russian payload.
2007 Computer Failure
On June 14, 2007 a computer malfunction on the Russian segment left the station without thrusters, oxygen generation, a carbon dioxide scrubber and other environmental control systems.
The primary systems were back online by June 15th, but without the secondary system that controls oxygen levels, the station had 56 days of oxygen available.
The malfunction was ultimately caused by condensation inside the electrical connectors and the computers were all back up and running on June 16th. Plans were implemented to prevent this problem in the future.
2007 Torn Solar Panel
On October 30, 2007, after relocating two solar arrays to their final position, a 76cm tear was noticed on the second array when it was roughly 80% deployed.
A spacewalk, which usually took months to plan, took place on Nov 3rd. The astronaut rode on the end of the spacecraft Discovery’s 50 ft boom arm to repair the damage. The repair was also considered to be more dangerous, relatively speaking, due to the possibility of shock from the solar array, using the boom arm, which hadn’t been done before, and the lack of pre-planning.
2007 Damaged Starboard Solar Alpha Rotary Joint
Side bar for a second to let you know about a little memory trick I have. Port and left are both four letter words. Therefore starboard must be the right. That is how I remember which is which.
Back to the rotary joint. The starboard joint, and a similar one on the port side, rotates the large solar arrays to keep them facing the sun. In October 2007, excessive vibration and high current spikes were noted in the drive motor. Inspection found extensive contamination from metallic shavings and debris in the large drive gear and damage to the large metallic race ring. The joint was locked in place until it could be repaired. In sept 2008, the crew cleaned and lubricated both the starboard and port joints and replaced 11 of 12 trundle bearings on the starboard joint. NASA developed a long term solution to install structural supports between the starboard and port joints and a new race ring between them to replace the failed joint. But they have found that cleaning and lubricating the joint had great results and will continue to maintain the joints this way until the failure can be fully analyzed.
Excessive Vibration during reboost
An incorrect command sequence on Jan 14, 2009 caused the Zvezda rocket propulsion control system to misfire during an altitude re-boost maneuver. Vibrations were felt in the station's structure for over two minutes. Further analysis ultimately determined that the station didn’t suffer any structural damage, although initially they had thought some components may have been stressed beyond their design limits.
2009 Potential Ammonia Leak from S1 Radiator Due to Damaged Panel
Damage to one of the external thermal control system radiators was noticed in September 2008. The surface of the sub-panel had peeled back from the underlying central structure. Speculation is that the damage was caused by a micro-meteoroid or debris impact, or perhaps a service module thrust cover that got loose during an earlier spacewalk. Although there was no evidence of a leak or even a reduction in the thermal performance of the panel, the panel's ammonia loop was closed off from the rest of the system. Imagine driving around in the summer and your AC stops working, except in space, you can’t exactly open the windows.
2010 Failure in Cooling Loop A
A failed ammonia pump module knocked out one of two external cooling loops and left the station with only half of its normal cooling capacity on August 1, 2010. An attempted replacement of the pump on Aug 7 found an ammonia leak in one of four quick-disconnects. The pump was replaced on Aug 11th and the loop function was restored.
2011 Near Collision with Space Debris
An unidentified object was seen on June 28, 2011 travelling at 47,000kph, 340m from the station. The six crew members at the station boarded the Soyuz capsule and closed all hatches. They were almost undocked from the station when the all clear was given and the debris had passed without incident.
2011-2012 Failure of Main Bus Switching Unit #1 and Replacement Extravehicular Activity
In late 2011, one of the four main bus switching units that routes power from the four solar array wings to the rest of the station stopped responding to commands or sending status info. A replacement mission on Aug 30, 2012 failed to be completed because a bolt jammed before the electrical connection was secured. With this bus switching unit down, the station was at 75% capacity, leading to minor limitations until it could be addressed.
If that wasn’t bad enough, a third solar array wing went offline due a fault in the direct current switching unit, further reducing capacity to five of eight solar array wings.
Power was restored to the station on Sept 5, 2012.
2012 Failure of Primary Carbon Dioxide Removal Assembly
On June 16th 2012, the main carbon dioxide scrubber in the lab shut down. There was a backup system, but it had issues with sticking valves and the crew only wanted to use it if necessary. The lab scrubber shut down was traced back to a failed temperature sensor. The crew tried to repair it, but due to erratic data, they decided to run the backup system, even with the sticking valve issues.
Then on June 13, 2013 the crew noticed white flakes floating away from the station, resulting from an ammonia leak. In September, one of the sticky air valves was replaced but the problems persisted and the standby carbon dioxide scrubber had to be restarted several times. The crew held onto the previously removed valves as back ups, just in case more problems persisted, but that was a last resort.
2018 Leak in Soyuz Orbital Module
A small pressure leak was noticed on Aug 29th, 2018 in the Russian segment. An investigation found a 2mm hole near the hatch of the Soyuz spacecraft. The hole was covered with Kapton tape, which from what I’ve read seems like space duct tape, and then an on board patch kit. Neither was a permanent solution and sealant was later applied to stabilize the station’s pressure.
2019-2020 Pressure Leak
A higher than normal air leak was detected in sept 2019. On sept 29, 2020 the leak was isolated to the Zvezda module and an attempt was made to patch it. Another leak in the section has led to consideration to close off the entire section and use oxygen reserves, but this would impact the entire station.
So there you have it, the ups and downs of the amazing International Space Station. Nothing too drastic happened, and no one was hurt, but I’m sure there were still some hairy moments up there for the crew. Not sure if you have seen the tv series Away. In it Hilary Swank is the commander of a mission to Mars. During the series, they lose the primary water reclamation system and the backup can’t get them all the way to Mars. They come up with a risky plan and ultimately are able to repair the primary system, but not without extensive rationing of water to the crew leading to extreme dehydration. Yes, this is fiction, and I’m sure there are several inaccuracies about the show, but one thing that I think they got right is that the crew has only themselves and the parts they brought with them to repair anything that goes wrong. And as I mentioned earlier, there are a lot of unknowns when it comes to space exploration, and anything could really go wrong.
I visited Houston in 2018 and was lucky enough to take a trip down the Space Centre. They have rockets and spacesuits on display, among other things. It was very cool. The space centre is huge, and the public only has access to a small part of it. In 1969 Schwinn donated a number of bicycles for employees to get around the station. Whether from your parking spot to your office, or from meeting to meeting, there are bikes everywhere. You just grab one that’s available and leave it for the next person. I don’t know why I found this bike thing so fascinating but it was very cool. Who goes to a space centre and falls in love with bikes?!? I guess I do.
Check out the podcast page, link in show notes, for photos from this week’s episode. If you’re enjoying what you’re hearing, please rate, review and subscribe to failurology, so more people can find it. And if you want to chat with me, my twitter handle is @failurology or you can email me at firstname.lastname@example.org.
Thanks everyone for listening. And tune in next week to hear about the Titanic, the unsinkable ship that sank on its maiden voyage. But more on that next week. Houston, this is Failurology, the Eagle has landed, over and out.