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REVOSAT
7 février 2008

ABOUT USA 193-

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march_revosatABOUT_USA_193
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We got photos of that satellite on 30 October 2007.19h18(1). Then we computed orbital elements with fast Kepler soft. and drew the last two spells of visibility on evening on February and March 2008.

The period of visibility is the time elapsed by the ascending node to precess 360°or 24 hours.

This period is 66 days dispatched in 49,25days and 16,75 days.

On the diagram, we see that there a first spell of ascending transits between 19 and 25 February and a second spell of descending transits between 4 and 10 March. Later the satellite will be decayed.

It appeared ,on the other hand, that inclination of orbit were 58.5° instead of 57° (Military satellites ex: Lacrosse 3 and 5) then we registered the precession of the argument of perigee to identify if that satellite was moving normally.

What a surprise! The argument of perigee is every ~20 days corrected to be ~100°.

On the scheme, perigee versus time, we reported the normal Keplerian movement of perigee (+1.55°/day) and the observed one.

The elements of the orbit were frozen to be a quasi circular one (eccentricity ~0)by using hydrazine rocket on board.

Why?. It is probably to control the decay till burning when entering high atmosphere.

A satellite with a frozen orbit is easier to be crashed into pacific ocean than with a changing one. It is quite the same , if US marine has to shoot it down with a missile .(NASA –Bush’s speech).

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