Herschel space telescope to become biggest space telescope

Bigger than Hubble, until the James Webb telescope is launched. Also it
seems to be the first telescope being put into one of the Earth-Sun
Lagrange points, Lagrange point 2 to be exact. James Webb is supposed to
into this Lagrange point too.

Yousuf Khan

BBC NEWS | Science & Environment | 'Silver sensation' seeks cold cosmos
"It is enchanting, spectacular and - at 3.5m in diameter - it will soon
become the biggest telescope mirror in space, surpassing that of Hubble."
http://news.bbc.co.uk/1/hi/sci/tech/7864087.stm

On Feb 9, 10:02*am, Yousuf Khan wrote:
Bigger than Hubble, until the James Webb telescope is launched. Also it
seems to be the first telescope being put into one of the Earth-Sun
Lagrange points, Lagrange point 2 to be exact. James Webb is supposed to
into this Lagrange point too.

* * * * Yousuf Khan

BBC NEWS | Science & Environment | 'Silver sensation' seeks cold cosmos
"It is enchanting, spectacular and - at 3.5m in diameter - it will soon
become the biggest telescope mirror in space, surpassing that of Hubble."http://news.bbc.co.uk/1/hi/sci/tech/7864087.stm

Are they going to firmware/software lock-out the Sirius star/solar
system?

~ BG

In article ,
Yousuf Khan writes:
Bigger than Hubble, until the James Webb telescope is launched.

Presumably referring to _Herschel_, which is supposed to be launched
later this year. Herschel is a far infrared mission; the shortest
wavelength it will observe is something like 60 microns. More
information at
http://sci.esa.int/science-e/www/are...cfm?fareaid=16
(I see the planned launch date is Apr 16.)

The same rocket (Ariane ECA, which I think must be some form of
Ariane 5) will launch _Planck_, a cosmic background mission.

Also it seems to be the first telescope being put into one of the
Earth-Sun Lagrange points, Lagrange point 2 to be exact.

I think WMAP is in an L2 orbit, and it wouldn't surprise me if other
satellites are there too.

James Webb is supposed to into this Lagrange point too.

Yep. L2 is a pretty good orbit, though as always there are
tradeoffs. L2 is fairly far from Earth and Moon so those bodies
don't contribute much heat input nor block the solar panels from a
full-time view of the Sun. Compared to a solar orbit (as Spitzer),
L2 takes more energy to get to, and station keeping is required, but
pointing restrictions are simpler and don't change over the mission.
Downlink rate is lower from L2 at mission start (for the same
transmitter power and directional antenna), but the rate is constant
rather than deteriorating during the mission. There are probably
other considerations as well, but it's not surprising to see L2 used.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email may be sent to your ISP.)

On Feb 10, 1:52*pm, (Steve Willner) wrote:
In article ,
*Yousuf Khan writes:

Bigger than Hubble, until the James Webb telescope is launched.

Presumably referring to _Herschel_, which is supposed to be launched
later this year. *Herschel is a far infrared mission; the shortest
wavelength it will observe is something like 60 microns. *More
information athttp://sci.esa.int/science-e/www/area/index.cfm?fareaid=16
(I see the planned launch date is Apr 16.)

The same rocket (Ariane ECA, which I think must be some form of
Ariane 5) will launch _Planck_, a cosmic background mission.

Also it seems to be the first telescope being put into one of the
Earth-Sun Lagrange points, Lagrange point 2 to be exact.

I think WMAP is in an L2 orbit, and it wouldn't surprise me if other
satellites are there too.

James Webb is supposed to into this Lagrange point too.

Yep. *L2 is a pretty good orbit, though as always there are
tradeoffs. *L2 is fairly far from Earth and Moon so those bodies
don't contribute much heat input nor block the solar panels from a
full-time view of the Sun. *Compared to a solar orbit (as Spitzer),
L2 takes more energy to get to, and station keeping is required, but
pointing restrictions are simpler and don't change over the mission.
Downlink rate is lower from L2 at mission start (for the same
transmitter power and directional antenna), but the rate is constant
rather than deteriorating during the mission. *There are probably
other considerations as well, but it's not surprising to see L2 used.

--
Steve Willner * * * * * *Phone 617-495-7123 * *
Cambridge, MA 02138 USA * * * * * * * *
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. *Commercial
email may be sent to your ISP.)

Selene L1 is nearly ideal, second only to Selene L2.

~ BG

On Feb 10, 4:52*pm, (Steve Willner) wrote:
Presumably referring to _Herschel_, which is supposed to be launched
later this year. *Herschel is a far infrared mission; the shortest
wavelength it will observe is something like 60 microns. *More
information athttp://sci.esa.int/science-e/www/area/index.cfm?fareaid=16
(I see the planned launch date is Apr 16.)

Yeah, seems to show the growing importance of the infrared band these
days. Even James Webb will be mostly in the infrared band. Hubble's
small footprint in the infrared seems to be its most useful.

The same rocket (Ariane ECA, which I think must be some form of
Ariane 5) will launch _Planck_, a cosmic background mission.

Yes, the article just barely mentioned the Planck telescope. Very
little detail about it, I don't even know if it's attached physically
to the Herschel, or if it'll separate upon arrival at the L2. Don't
even know what band it's going to be observing.

Also it seems to be the first telescope being put into one of the
Earth-Sun Lagrange points, Lagrange point 2 to be exact.

I think WMAP is in an L2 orbit, and it wouldn't surprise me if other
satellites are there too.

Interesting. I wonder how crowded it's getting up there? Will we be
having space junk problems there soon?

James Webb is supposed to into this Lagrange point too.

Yep. *L2 is a pretty good orbit, though as always there are
tradeoffs. *L2 is fairly far from Earth and Moon so those bodies
don't contribute much heat input nor block the solar panels from a
full-time view of the Sun. *Compared to a solar orbit (as Spitzer),
L2 takes more energy to get to, and station keeping is required, but
pointing restrictions are simpler and don't change over the mission.
Downlink rate is lower from L2 at mission start (for the same
transmitter power and directional antenna), but the rate is constant
rather than deteriorating during the mission. *There are probably
other considerations as well, but it's not surprising to see L2 used.

What do you mean Spitzer is in a Solar orbit? Is it in the same Solar
orbit as Earth (just a little bit further ahead or behind)? Or is it a
little larger or smaller solar orbit?

Yousuf Khan

On Feb 10, 6:01*pm, YKhan wrote:
On Feb 10, 4:52*pm, (Steve Willner) wrote:

Presumably referring to _Herschel_, which is supposed to be launched
later this year. *Herschel is a far infrared mission; the shortest
wavelength it will observe is something like 60 microns. *More
information athttp://sci.esa.int/science-e/www/area/index.cfm?fareaid=16
(I see the planned launch date is Apr 16.)

Yeah, seems to show the growing importance of the infrared band these
days. Even James Webb will be mostly in the infrared band. Hubble's
small footprint in the infrared seems to be its most useful.

The same rocket (Ariane ECA, which I think must be some form of
Ariane 5) will launch _Planck_, a cosmic background mission.

Yes, the article just barely mentioned the Planck telescope. Very
little detail about it, I don't even know if it's attached physically
to the Herschel, or if it'll separate upon arrival at the L2. Don't
even know what band it's going to be observing.

Also it seems to be the first telescope being put into one of the
Earth-Sun Lagrange points, Lagrange point 2 to be exact.

I think WMAP is in an L2 orbit, and it wouldn't surprise me if other
satellites are there too.

Interesting. I wonder how crowded it's getting up there? Will we be
having space junk problems there soon?

Earth L2 is a very large volume of space, room for safely
accommodating dozens to hundreds of large satellites.



James Webb is supposed to into this Lagrange point too.

Yep. *L2 is a pretty good orbit, though as always there are
tradeoffs. *L2 is fairly far from Earth and Moon so those bodies
don't contribute much heat input nor block the solar panels from a
full-time view of the Sun. *Compared to a solar orbit (as Spitzer),
L2 takes more energy to get to, and station keeping is required, but
pointing restrictions are simpler and don't change over the mission.
Downlink rate is lower from L2 at mission start (for the same
transmitter power and directional antenna), but the rate is constant
rather than deteriorating during the mission. *There are probably
other considerations as well, but it's not surprising to see L2 used.

What do you mean Spitzer is in a Solar orbit? Is it in the same Solar
orbit as Earth (just a little bit further ahead or behind)? Or is it a
little larger or smaller solar orbit?

* Yousuf Khan

It should get parked within the Selene/moon L1, but that would be
asking too much, and extremely hot much of the time. Otherwise, the
Selene/moon L2 would require a couple of transponders.

~ BG

In article ,
YKhan writes:
Yeah, seems to show the growing importance of the infrared band these
days. Even James Webb will be mostly in the infrared band. Hubble's
small footprint in the infrared seems to be its most useful.

As a career infrared astronomer, I certainly won't argue with the
first two sentences. :-) That last one about Hubble seems a bit
dubious, though. NICMOS is nice but has a tiny field of view and
doesn't get very much of Hubble's observing time. Are you confusing
it with Spitzer?

Yes, the article just barely mentioned the Planck telescope. Very
little detail about it,

The Planck home page was hard to find, but it seems to be at
http://sci.esa.int/science-e/www/obj...objectid=33333

I don't even know if it's attached physically
to the Herschel, or if it'll separate upon arrival at the L2.

See http://sci.esa.int/science-e/www/obj...objectid=34727
Separation will be "shortly after launch."

I wonder how crowded it's getting [in L2]? Will we be
having space junk problems there soon?

Not likely ever to be a problem. See
http://sci.esa.int/science-e/www/obj...objectid=34728
(and note especially "not to scale" on the figure). The "Lissajous
orbit" is something like 10^5 km in radius IIRC around L2 itself.

What do you mean Spitzer is in a Solar orbit? Is it in the same Solar
orbit as Earth (just a little bit further ahead or behind)? Or is it a
little larger or smaller solar orbit?

Very slightly larger; orbit period is about 363 days. See
http://www.spitzer.caltech.edu/about/now.shtml
I couldn't find a good illustration of the orbit, but there may be
one somewhere on that site. This is a low-launch-energy orbit with
good telecom at the start of mission, but keeping the high data rate
now requires the 70-m DSN antennas.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email may be sent to your ISP.)

On Feb 11, 4:52*pm, I wrote:
In article ,
[Spitzer Space Telescope orbit is]
Very slightly larger [than Earth's]; orbit period is about 363 days.

Either I can't type, can't add, or think a year is 355 days -- or
maybe more than one of the above. :-) Spitzer's orbit is about 8 days
longer than a year; that _might_ work out to 373 days or so.

On Feb 11, 5:52*pm, Steve Willner wrote:
On Feb 11, 4:52*pm, I wrote: In article ,

[Spitzer Space Telescope orbit is]

Very slightly larger [than Earth's]; orbit period is about 363 days.

Either I can't type, can't add, or think a year is 355 days -- or
maybe more than one of the above. :-) *Spitzer's orbit is about 8 days
longer than a year; that _might_ work out to 373 days or so.

Why can't Spitzer look for Sirius C?

~ BG

On Feb 11, 4:52*pm, (Steve Willner) wrote:
As a career infrared astronomer, I certainly won't argue with the
first two sentences. :-) That last one about Hubble seems a bit
dubious, though. *NICMOS is nice but has a tiny field of view and
doesn't get very much of Hubble's observing time. *Are you confusing
it with Spitzer?

I was just observing that a lot of really far away galactic images
from Hubble tend to be false-color images, which would indicate to me
that they've been enhanced to allow our visual range to perceive it.
That indicates that perhaps most of them are in the infrared range.

Yes, the article just barely mentioned the Planck telescope. Very
little detail about it,

The Planck home page was hard to find, but it seems to be athttp://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33333

Ah, I see, so it's a successor to the COBE and WMAP Cosmic Microwave
Background mapping satellites.

I wonder how crowded it's getting [in L2]? Will we be
having space junk problems there soon?

Not likely ever to be a problem. *Seehttp://sci.esa.int/science-e/www/object/index.cfm?fobjectid=34728
(and note especially "not to scale" on the figure). *The "Lissajous
orbit" is something like 10^5 km in radius IIRC around L2 itself.

Are these stable orbits, i.e. doesn't require thrusters to keep them
going?

Yousuf Khan