Venus Express orbit changes.

[Notebook]

Just looking at the Venus Express site, and this page:-

http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=43110

shows four manouvers over several weeks.

I'm wondering why they didn't do it in one or two, and why the intervals between maouvers?

Being cautious, or operational reasons, tracking sites...?

N.

 

[Urwumpe]

being cautious, I would say - after each maneuver you can see how the tracking station measures the new orbit to predict errors.

 

[Notebook]

That makes sense, can't be too carefull!
The ratios of the burns are interesting, they go

3.6 : 27 : 10 : 10

I would have thought they would have had a constant ratio, or some form of prgression?

N.

 

[tony]

Keep in mind that lots of times final correction burns are canceled because the previous ones were right on the money.

 

[Andy44]

The ratios of the burns are interesting, they go

3.6 : 27 : 10 : 10

I would have thought they would have had a constant ratio, or some form of prgression?

The purpose of this is to characterize the thrusters, to get a good read on the performance they deliver. By the time you get the 4th burn, you should have your thruster model pretty well tweaked so that you can nail the final orbit dead on.

Otherwise you wind up having to do expensive corrections.