[Coco] Re: Re: off-topic, space program

[Lawrence Weeks]

Once upon a time (Sun Jan 18), Gene Heskett wrote:

> The gyros on the other hand, will if mechanically turned to change the 
> axis, cause a precession motion for the whole hubble as its not 
> exactly bolted to anything. These effects can be used to steer it as 
> long as the gyros run.

> That may have driven the choice to use mechanical gyros as opposed to 
> interferometers, all the energy the gyros need is from the solar 
> panels. Constantly refreshed in other words.

Almost. Hubble uses four "reaction wheels" which are large dense
flywheels basically. One for each axis. The gyros are used to instruct
the reaction wheels to turn appropriately. This (simple) technology
has been used in a number of satellites.

I imagine that the hoped-for two gyroscope software would use two
in addition to sightings from the star tracking sensor to provide
orientation.

Larry
-- 
Lawrence Weeks                                    lweeks at anabasis.net
Anabasis Consulting Ltd