Update from ESA’s Mike Steinkopf, Mission Director at ATV-CC tonight, on this evening’s first set of manoeuvres following today’s rather smooth undocking. Mike describes the aim of this week’s orbital manoeuvres: to bring ATV on Saturday into a position below the ISS and in the field of view of ISS optical instruments (to allow for observation of ATV during its controlled atmospheric re-entry).
The two planned TP manoeuvres were successfully performed this evening with less than 0.1% percent error.
The two manoeuvres tonight were the ‘Transfer to Phasing’ orbit manoeuvres (i.e. matching ATV’s orbit with that of the ISS) TP1 and TP2, and these took place at 21:06 and 21:48 CET.
Delta velocities (i.e. changes in velocity) applied were about 11.78 m/s with a duration of about 3 minutes each, and these brought ATV down to a lower orbit with reference to the ISS. Being on a lower orbit means that ATV will overtake the ISS during the next days.
Today’s two manoeuvres are the start of a series of manoeuvres that are planned to take place during this week.
ATV is now in a ‘Drift on Phasing’ orbit and the next manoeuvres will be the Mid-Course manoeuvres (MC1, MC2) planned on Thursday; these are manoeuvres to adjust for manoeuvre dispersions and orbit perturbations.
On Friday, these will be followed by the last two ‘Transfer to ISS Vicinity’ manoeuvres (TV1, TV2).
Basically, what we are doing this week is a sort of ‘virtual rendezvous’ with the ISS, but on a lower altitude, before the two De-Orbit manoeuvres DEO1 and DEO2, set to take place on Saturday – hence the terminology for these manoeuvres is identical to the pre-docking rendezvous manoeuvres conducted earlier this year.
The objective is to bring ATV on Saturday into a position below the ISS and in the field of view of ISS optical instruments to allow for observation of ATV during its controlled atmospheric re-entry in an altitude range from about 115 km down to 65 km.
– Mike Steinkopf