A replacement Air Quality Monitor will be launched on the next Progress resupply mission to aid the investigation into increased levels of benzene in the International Space Station’s atmosphere.
The first detection of off-nominal levels occurred on April 13, when Air Quality Monitor-1 – or AQM-1 – detected benzene in the atmosphere that was slightly above the reporting limit. At the time, AQM-1 was located inside the US Lab, otherwise known as the “Destiny” module.
From April 13 to April 29, the amount of benzene in the atmosphere of the ISS remained around 0.065 mg/m^3. However, on April 29, the amount of benzene began to rise on an “increasing trend.” This trend continued to rise, eventually breaking the 30 day Spacecraft Maximum Allowable Concentration (SMAC).
According to the Centers for Disease Control and Prevention, benzene is a “chemical that is a colorless or light yellow liquid at room temperature. It has a sweet odor and is highly flammable.” If there are very high levels of exposure, an individual can suffer from adverse health effects.
On May 15, the Lab Trace Contaminant Control System (TCCS) was activated in response to elevated amounts of benzene per Air Quality Monitor sensor readings. By May 19, the levels were still “slightly high.”
The teams on the ground continued to look for the source of the problem. Next, Air Quality Monitor-1 was relocated to the Russian Segment of the ISS on June 9. This action was done to collect “baseline atmospheric data.”
The AQM inside the Russian segment of the ISS. Photo Credit: NSF L2.
Joint Operations Commander Bob Behnken and Spacecraft Commander Doug Hurley arrived to the ISS onboard Dragon Endeavour on May 31. Endeavour is currently docked to the IDA-2 docking adapter, which is attached to the PMA-2 port on the Harmony module.
The arrival, docking, and stay aboard the station for the Demo-2 mission is not believed to have any effect on the benzene level issue on the ISS.
Currently, the station has a crew of five onboard, which includes Expedition 63 Commander Chris Cassidy and Expedition 63 flight engineers Anatoly Ivanishin (Soyuz MS-16 Commander), Ivan Vagner, and now Bob Behnken and Doug Hurley.
Expedition 63 began on April 17 when Oleg Skripochka, Jessica Meir, and Andrew Morgan departed the ISS on Soyuz MS-15. The expedition is expected to last until Ivanishin, Vagner, and Cassidy depart in October.
The Expedition 63 crew shown inside the Harmony module after the arrival of Endeavour. Photo Credit: NASA Johnson.
On June 13, the Split Inter-Module Ventilation (IMV) between the US and Russian segments occurred. The data from this showed a rise in benzene levels. Russian controllers also deployed the portable scrubber (AFOT) in an attempt to test its effectiveness in removing the benzene.
To further the investigation into the source of the leak, the atmosphere between the American and the Russian segments was isolated on June 18.
Overnight on June 18, two additional benzene readings were taken. However, the planned leak tests were canceled due to a failure of the AQM. After the failure, the atmosphere inside the ISS was “re-integrated” once again between the two segments were opened. The failed AQM was returned to the US segment from the Russian segment inside the ISS.
L2 ISS information, AQM-1 is the only on-orbit analyzer that detects benzene. Troubleshooting attempts were made by the crew but were unsuccessful. The information also noted the AQM “cannot be repaired on orbit.”
The investigation into the benzene levels will now remain on hold until a brand new AQM arrives on board the next Progress resupply spacecraft to launch and dock to the ISS, Progress 76P (also known as Progress MS-15). Progress MS-15 is currently undergoing preparations at the Baikonur Cosmodrome in the Republic of Kazakhstan.
The launch of Progress MS-15 is currently scheduled to occur on July 23, from Site 31/6.
The Progress MS-15 spacecraft. Photo Credit: RSC Energia.
Meanwhile, Expedition 63 crew members installed four fresh Charcoal HEPA Integrated Particle Scrubbers (CHIPS) filters on Node 1 “Unity” to filter out the Benzine in the atmosphere on the station.
These four new filters were previously stored inside the Bigelow Expandable Activity Module (BEAM) before their installation inside Node 1. The BEAM module was launched onboard SpaceX Dragon C110 during the CRS-8 mission in 2016.
This year, the ISS is celebrating the 20th anniversary of continuous human occupation that was started by William Shepherd, Yuri Gidzenko, and Sergei Krikalev on Expedition 1 in 2000. The first mission to dock to the ISS was STS-88 on Space Shuttle Endeavour in 1998.
As the International Space Station continues to operate, more maintenance will be needed. Some of the original modules are starting to show their age. The first module of the ISS, the Functional Cargo Block (FGB or “Zarya” was launched on Nov 20, 1998. The spacecraft specifically launched from Site 81 at the Baikonur Cosmodrome in Kazakhstan.
The station has already outlasted the former Mir Space Station, which was the longest active station before the ISS. As of now, the ISS will continue to operate in its current form through to 2030.