Stupid question about Hubble

Does Hubble perform observations while in direct sunlight (ie the
period of its orbit when it is not in the Earth's shadow.

If not, then a propulsion system like that of Orbital Recovery could
be used to change the Hubble orbit while Hubble was not being used (ie
when on the sunlit portion of its orbit).

(Explorer8939) wrote in
om:

Does Hubble perform observations while in direct sunlight (ie the
period of its orbit when it is not in the Earth's shadow.

Yes. Because it operates in a vacuum, light scattering is not
a problem; the only constraint is not pointing too closely in the
direction of the Sun and Moon (usually), and the Earth (obviously).

If not, then a propulsion system like that of Orbital Recovery could
be used to change the Hubble orbit while Hubble was not being used (ie
when on the sunlit portion of its orbit).

Hubble does not use a propulsion system, to prevent contamination of
the precision optics. Pointing is accomplished by flywheels and
magnetic torquers.

Something like an orbital tug could be occasionally useful for tasks
like this, however.

--Damon

In article ,
Explorer8939 wrote:
Does Hubble perform observations while in direct sunlight (ie the
period of its orbit when it is not in the Earth's shadow.

In general, yes. There are astronomy spacecraft which can work
effectively only when in shadow, but Hubble is not one of them.
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

"Explorer8939" wrote:
Does Hubble perform observations while in direct sunlight (ie the
period of its orbit when it is not in the Earth's shadow.

Yes, it does, routinely. Hubble has a shade that extends
well beyond the position of the secondary mirror as well
as a system of interior light baffles. The lack of an
atmosphere in orbit allows Hubble to view stars even while
it is in direct sunlight, provided the telescope is kept
pointed a minimum angle away from the Sun.

Interestingly, future telescopes will be even more in the
Sun than Hubble is currently, as they will go into higher
orbits, Solar orbits, or other locations farther from
Earth (e.g. Earth-Sun Lagrange points). Both the JWST
and the SIRTF will be in direct sunlight essentially all
the time. Both will employ systems to keep the light out
of the optical systems though. In fact, JWST will deploy
a large sunshade that will keep the entire optical
assembly (including the instruments) in permanent shadow.

"Christopher M. Jones" wrote in message
...
"Explorer8939" wrote:
Does Hubble perform observations while in direct sunlight (ie the
period of its orbit when it is not in the Earth's shadow.

Interestingly, future telescopes will be even more in the
Sun than Hubble is currently, as they will go into higher
orbits, Solar orbits, or other locations farther from
Earth (e.g. Earth-Sun Lagrange points). Both the JWST
and the SIRTF will be in direct sunlight essentially all
the time. Both will employ systems to keep the light out
of the optical systems though. In fact, JWST will deploy
a large sunshade that will keep the entire optical
assembly (including the instruments) in permanent shadow.

For a lot of applications being in sunlight all the time is more desirable
than constantly going into and out of the sunlight. A stable thermal
environment (as opposed to the cycling the Hubble does every 90 minutes)
makes for a more stable telescope.

Jason

Christopher M. Jones wrote:
"Explorer8939" wrote:

Does Hubble perform observations while in direct sunlight (ie the
period of its orbit when it is not in the Earth's shadow.


Yes, it does, routinely. Hubble has a shade that extends
well beyond the position of the secondary mirror as well
as a system of interior light baffles. The lack of an
atmosphere in orbit allows Hubble to view stars even while
it is in direct sunlight, provided the telescope is kept
pointed a minimum angle away from the Sun.

Interestingly, future telescopes will be even more in the
Sun than Hubble is currently, as they will go into higher
orbits, Solar orbits, or other locations farther from
Earth (e.g. Earth-Sun Lagrange points). Both the JWST
and the SIRTF will be in direct sunlight essentially all
the time. Both will employ systems to keep the light out
of the optical systems though. In fact, JWST will deploy
a large sunshade that will keep the entire optical
assembly (including the instruments) in permanent shadow.



I had thought being at L2 the JWST would enjoy the
shade of the earth and moon.

Hop
http://clowder.net/hop/index.html

In article ,
Hop David wrote:
The moon could be anywhere from 0 to 14 degrees from the earth so it
seems to me the craft might see lunar ecclipses on very rare occasions.

More precisely, solar eclipses by the Moon. Yes, this is something
satellite planners have to be aware of. JWST will be too far away for
this to be a big issue, but closer to home it can be quite significant.

(The worst case of such things is a lunar orbiter during a total lunar
eclipse, when the Moon is in the Earth's shadow for *hours*.)
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |