In mid-May, ATV Johannes Kepler is scheduled to conduct the first refuelling of the ISS. The transfer of propellant from Kepler to the ISS is split into five steps. The first took place on 18 February with a check of the electronics and systems used for the refuelling.
On the 22 March, mission controllers at ATV-CC conducted leak tests – see our earlier post below – to confirm that the fuel line connections between ATV and the ISS were sealed.
The final three steps – including the actual transfer of fuel – are planned for the 17-19 May. Here are a few more interesting details on the 22 March leak tests, courtesy of our colleagues at le blog de l’ATV-2 at CNES.
Didier Collin, Flight Director at ATV-CC, reports on the details of the 22 March check:
On the 22 March between 2:00 and 9:00 CET, the leak test of the propellant transfer lines for the ISS was held. This test was essentially to ensure that the connections between the ISS and ATV-2 were completely sealed (this is a mandatory prerequisite to allow the transfer of fuel). This operation involved injecting helium into the injector channels until it reached a pressure of about 19 kgf/cm2 and then verifying the changes in temperature and pressure for about 28 minutes. After a thorough inspection, no leaks were detected.
The operation was carried out in close coordination between ATV-CC and MCC-M (TsUP – the ISS control centre in Moscow). Three steps were necessary: first, set ATV and the fuel transfer system into a specific configuration. Second, conduct the actual leak test (sequentially check the lines by pressurizing them, opening/closing the values and continuous checking of pressures and temperatures) using the ISS computer according to instructions prepared by TsUP. Finally, reconfigure ATV to its dormant mode (done by ATV-CC).
Throughout the test, Russian and European experts monitored progress; successful completion will now enable the transfer of propellant as expected in mid-May.