Progress 29P launches towards ISS – Freon leak update

by Chris Bergin

The Russian resupply vehicle Progress M-64/29P has launched on a Soyuz launch vehicle from the Baikonur Cosmodrome in Kazakhstan. The vehicle will dock with the International Space Station on Friday.

Meanwhile, evaluations are also continuing on the freon coolant leak in the Russian segment of the Station – as efforts to removed contaminants via the US Carbon Dioxide Removal Assembly (CDRA) have not performed as well as expected.

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Progress Launch:

The vehicle is carrying over two tons of supplies to the orbital outpost, including fuel, food, water, oxygen, clothing and personal items – including a new Sokol KV-2 spacesuit for Sergey Volkov. In total, Progress M-64’s mass at launch is 7056 kg.

Orbital insertion of the vehicle is expected at 4:31:39pm, with three midcourse correction burns (DV1: 5/14 – 7:58pm; DV2: 5/14 – 8:39pm; DV3: 5/15 – 5:06pm) to follow. Six more course adjustment ‘tweaks’ will be executed later as required.

On Friday, Progress’ KURS docking system will be activated at 4:04pm EDT on Daily Orbit 16 (DO16), with progress’ headlights will be switched on at a range of eight km. Flyaround to the FGB nadir docking port (400 meter range, in sunlight) starts at 5:14pm.

The automated vehicle will begin its final approach at 5:27:30pm, with the estimated time of contact with the Station at the FGB Nadir port around 5:36:30pm.

Freon leak update:

As previously reported, there was a freon (Russian name for this type of freon is Khladon. Also known as Freon 218) leak inside the ISS when the crew was performing maintenance on one of the Russian Segment coolant loops.

Approximately 600g was dispersed in the atmosphere, which led to discussions by controllers on two impacts that this incident held.

‘First, this coolant loop is required to both collect condensate in the Russian segment, and it is also necessary to process US condensate water so that it can be used by the Elektron to generate O2,’ noted a memo updating status this week on L2.

‘Until the Russians can recharge their coolant loop with additional freon (manifested on Progress 29P) thermal loop setpoints were adjusted to ensure condensate collection in the USOS (United States On-orbit Segment) storing the condensate in the US lab tank.

‘The second impact was air quality. Although the freon concentration in the air is well below any toxic concern concentration (also known as SMAC (Spacecraft Maximum Allowable Concentration)), it is desirable to scrub the air to concentration levels at or below the Russian standard.

‘Three systems are effective at scrubbing the Freon. The first is the US Trace Contaminant Control System (TCCS). This is a charcoal based system which will saturate with freon fairly rapidly (won’t effect the TCCS ability to scrub other compounds). The second is the Russian air purifier.

‘That system – the BMP – absorbs freon into a catalyst bed and then exposes the bed to vacuum to vent the contaminants and regenerate the bed. Our Russian colleagues are increasing their regeneration rate of the BMP to speed up scrubbing.

‘However, since the scrub rate for the TCCS plus the BMP would take several months to reach the Russian health standard for freon, we have also turned on the Carbon Dioxide Removal Assembly (CDRA).

‘The CDRA works basically on the same principle as the Russian BMP. Because of the bed chemistry and cycle rate of the CDRA, when it is added to the TCCS and BMP, the estimated time to scrub the atmosphere reduces to around 5 days.’

However, the CDRA was eventually turned off, after it was found to make little difference to removing the contaminants. The likely cause is that the pore size of the Zeolite bed in CDRA is smaller than Freon molecules, thus preventing the refrigerant from being adsorbed.

‘After running the CDRA for several days, onboard measurements of freon showed no appreciable improvement. Therefore, the CDRA was not as effective at removing freon as believed, and it has been deactivated.’

The crew was – and remains – in no danger with regards to the leak. Further updates will be provided when available.

L2 members: All documentation – from which the above article (shuttle element) has quoted snippets – is available in full in the related L2 sections, updated live.

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