REVOSAT

suivi des satellites artificiels

02 avril 2008

PRECESSION OF ATV AND ISS BEFORE DOCKING

revosat_mai_PRECESSION_OF_ATV_AND_ISS__BEFORE_DOCKING
revosat_maiDocking_ATV

 

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During march ATV jules Verne(ESA) has been launched to be docked to ISS. (Inclination 51.6°)
See photo of ISS. The dashed trajectory on the photo allowed to get the time elapsed between two points (one period =1.6 second) then to compute the inclination, height and ascending node according to fast Kepler.
The docking is effective usually after two days, when it is Shuttle (NASA) or Progress but with ATV many experiments have been carried out so the docking has been effective only ~one month later.
We collected the RAAN of the two satellites to observe the different precessions and the argument of perigee to observe the use of their motors during the month.
We can see on the diagrams that the variation of the RAAN is –5.16 degrees/day relative to ISS and –5,207° /day relative to ATV.
ISS being always higher than ATV so more distant from the equatorial bulge  explains that ISS precession is smaller.
As for the perigee of ISS, it must have been regularly increasing because inclination is 51,6>63,4°( inclination inducing no movement of perigee).It is not the case .ISS manoeuvred to avoid debris of USA 193 recently destroyed with an inclination ~58° not very far from 51.6°.We can see the manoeuvres of ATV whenever perigee argument changed.

Posté par revosat à 23:27 - Observation - Commentaires [1] - Permalien [#]

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