(Updated 15 June with thruster firing times.) Before undocking from the ISS on 20 June, ATV-2 Johannes Kepler will undertake a crucial ‘double support’ function on 12 and 15 June. ESA’s ATV – the ‘little vessel that can’ – will fire its thrusters to raise the orbit of the ISS in two consecutive double, or bi-, boosts.
It’s the International Space Station’s biggest increase in altitude to date, and, thanks to ATV, it will significantly improve the 417-tonne Station’s orbital mileage through the next decade of scientific research.
Animation of ATV Jules Verne reboost in 2008 – now it’s Kepler’s turn – and it’s gonna be a lot bigger!
ATV Johannes Kepler is raising the ISS altitude from around 345 km to about 380 km, where it will use far less fuel to maintain its orbit and cutting the amount of fuel that must be sent up in the coming years by almost half.
The reboost pairs will run 36 & 40 mins and will take place on 12 and 15 June. During the thruster firings, the ISS’s spatial orientation will be maintained by separate thrusters on the Zvezda module and Progress M-10M that will also fire. on 12 June, the engines will be started at 16:10 and 20:15 CEST; after the burns, the altitude of the station is estimated to be 19.2 km higher.
We spoke with Ludovic Rochas, CNES Flight Director at ATV-CC (click on ‘Full article’ for more details).
Firstly, what is a ‘bi-boost’?
This is an operation that allows the ATV to raise the orbit of the station through two boosts, i.e. two sets of thruster burns of ATV’s eight Orbital Correction System (OCS) thrusters. In the case of the 12- and 15-June burns, it is necessary to conduct the thrusts in two sets of two due to the way that the ATV fuel system pumps propellant and so as to allow the thrusters to cool down for a bit between firings.
Is this a first for ATV? Did such an operation take place with ATV-1 Jules Verne in 2008?
Such a boost was not done with ATV Jules Verne, so this is a ‘first’ for ATV. This boost is one of the main activities of the ATV Kepler mission. Each of these burns will consume about 1400 kg of propellant.
What’s happening with the ESA/CNES teams at ATV-CC during the boost?
During these operations, ATV is activated and monitored by the mission control engineers at ATV-CC. We check in particular the engines and we adjust the power supplied by the Station to the ATV. We also watch the telemetry sent by ATV quite closely.
The engineers at ATV-CC are ready to react to any failure such as a loss of power or communications between the ISS and the ATV or engine failure of the ATV. At the end of the reboosts, ATV-CC will reconfigure the ATV mode back to the so-called ‘dormant’ mode and adjust the on-board flight parameters to accommodate the new orbit and attitude of the ISS.