James Webb telescope...
- Thread starter Darmok
- Start date
Gingerbeard
Ayup Me Duck
Poor choice of words, the remnants is what I really meant, like with the Helix Nebula https://en.wikipedia.org/wiki/Helix_Nebula
Sue Pertwee-Tyr
Accuphase all the way down
I'm really not clear how this orbit works. That animation doesn't show a full year. As it stands, it looks as though the telescope 'orbits' the L2 point, but AFAIK there is no massive object at L2 which would enable anything to achieve a stable orbit.This is the L2 orbit.
All this to get the telescope far enough away from the Earth and Sun to take a good picture.
Joe
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
Steve,
I was going for an animated gif that played in the post for illustration, but this video gives a clearer picture of what's happening.
The James Webb telescope is in orbit around the Sun, not the Earth. The massive object that enables a stable orbit is the Sun (mostly) and the Earth (a wee bit).
A good explanation is here: https://www.nasa.gov/topics/universe/features/webb-l2.html
Sorry, crazy busy day so links mainly.
Joe
I was going for an animated gif that played in the post for illustration, but this video gives a clearer picture of what's happening.
The James Webb telescope is in orbit around the Sun, not the Earth. The massive object that enables a stable orbit is the Sun (mostly) and the Earth (a wee bit).
A good explanation is here: https://www.nasa.gov/topics/universe/features/webb-l2.html
Sorry, crazy busy day so links mainly.
Joe
Joe P
Memory Alpha incarnate | mod; Shatner number = 2
P.S. Reading about the engineering behind the telescope and the cosmological reasons for launching it into orbit to the L2 point — a region in space where it can detect faint infrared radiation — makes you realize that the device is almost as complicated as an LP12! However, the telescope has to work for at least a decade without a trip to the dealer to tweak the suspension, change the belt, or upgrade the cartridge.
Sue Pertwee-Tyr
Accuphase all the way down
Thanks Joe, there's a line in the explanation at that NASA link that says "The Webb telescope will be placed slightly off the true balance point, in a gentle orbit around L2" so I'm correct in what I took from the GIF. And I do understand that the Lagrange points orbit the sun, because the Earth does. What I can't visualise is how Webb orbits L2 (which itself orbits the sun, hence Webb orbits the sun). If there was a massive object at L2 for Webb to orbit that'd make sense but I reckon I'd have heard of it before, had that been the case. So I'm assuming the oscillatory nature of the Webb orbit around the sun, which gives rise to the 'orbit' around L2, is a clever solution of the three body problem or sumfink.
matthewr
spɹɐʍʞɔɐq spɹoɔǝɹ ɹnoʎ sʎɐld
I think it's more SME Model 30. Hubble is the LP12 and in a few years people will be praising the Hubble images as somehow having more "soul" than the JWST ones
Jim Audiomisc
pfm Member
L2 is a 'point of stability' because any sight movement away from it tends to cause the combined Earth+Sun attraction to pull something back towards the L2 point... which orbits with the Sun - Earth line. So if you're *slightly* away from L2 you can nudge a velocity at right angles to it and the result is an 'orbit about L2'.
If you rhink that's fun, look up Kleperer Rosettes, etc.
You'd think no-one has ever read "Ringworld" or even Dyson. 8-]
FWIW Webb prompted me to re-read the Ringworld books. Still good stuff.
Seeker_UK
Feelin' nearly faded as my jeans
I think it's more SME Model 30. Hubble is the LP12 and in a few years people will be praising the Hubble images as somehow having more "soul" than the JWST ones
Do you think it captures / reproduces the inky blackness of space better?
matthewr
spɹɐʍʞɔɐq spɹoɔǝɹ ɹnoʎ sʎɐld
It was so profound my wife popped her head in from the next galactic cluster and asked if I had done another upgrade.
Seeker_UK
Feelin' nearly faded as my jeans
That reminds me of a customer I once served in Andys.
Customer: That last album they did (*), was sooo heavy, first time I played it, I had to call the wife in.
Customer wife: He said "Love. Stop what you're doing and come and listen to this. It's sooo heavy." and it was - it was sooo heavy. It was the drums.
From that point forward, whther you'd need to call your wife in became the benchmark for heaviness.
(*) INXS - Live Baby Live. Yeah, I know...
MarkW
Full Speed & Pagan
L2 is a 'point of stability' because any sight movement away from it tends to cause the combined Earth+Sun attraction to pull something back towards the L2 point... which orbits with the Sun - Earth line. So if you're *slightly* away from L2 you can nudge a velocity at right angles to it and the result is an 'orbit about L2'.
If you rhink that's fun, look up Kleperer Rosettes, etc.
You'd think no-one has ever read "Ringworld" or even Dyson. 8-]
FWIW Webb prompted me to re-read the Ringworld books. Still good stuff.
Except of course that the Ringworld is not in orbit around it's star - i.e. its speed of rotation is not what keeps it in a stable position relative to the centre of mass of the system. Acknowledged by Niven (and mentioned I think in Ringworld Engineers but that book is a bit dull and I may have nodded off...)
Kleperer Rosettes are fascinating but the maths melt my noggin so I try not to think about them too much
Tantris
pfm Member
JWST has been imaged by the Virtual Telescope Project just after it reached L2 orbit. I find that quite impressive!
I bought a 12" dobsonian a few years back with the aim of seeing many of the Messier objects. It's good fun, but you do have to be quite dedicated, and it would undoubtedly be much easier in an area with less light pollution.
I bought a 12" dobsonian a few years back with the aim of seeing many of the Messier objects. It's good fun, but you do have to be quite dedicated, and it would undoubtedly be much easier in an area with less light pollution.
Jim Audiomisc
pfm Member
Kleperer Rosettes are fascinating but the maths melt my noggin so I try not to think about them too much
The maths essentially follows from the pretty symmetry. My problem is when it comes to trying to think about 3D sets of objects that might make similar 'stable' configurations when the items are not all in a 2D plane. In general, 3D arrangements of 3 or more items will be expected to be chaotic I think. But are there exceptions?
Sadly, none of that would save us now from the mess we've made of putting vast numbers of 'bits' into all kinds of orbits around Earth. Serious cascading junk problem looms. Even before astronomy from the ground started to be really messed up all the added cubesats-for-profit.
