Space Launches, Landings & Destinations v4

[The Anti-Targ]

8 minutes ago, Loge said:

No, that will need a boost from its own engine. The last stage brought it up to just below escape velocity. 

According to this flight tracker it is well on it's way, and no longer in earth orbit https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html

[polishgenius]

If I've understood everything correctly, it's in a transfer orbit, ie an elliptical one that'll take it to L2, at which point it'll use its own boost to transfer into a halo orbit around L2. 

So it is on its way and doesn't need or want to reach actual escape velocity from Earth before the transfer, no? 

[Loge]

 

2 minutes ago, polishgenius said:

If I've understood everything correctly, it's in a transfer orbit, ie an elliptical one that'll take it to L2, at which point it'll use its own boost to transfer into a halo orbit around L2. 

So it is on its way and doesn't need or want to reach actual escape velocity from Earth before the transfer, no? 

That would make sense.

[SpaceChampion]

2 hours ago, Corvinus85 said:

Well I missed it, but glad it was successful.

I queued the video stream recording up to the launch time here:

 

[A True Kaniggit]

Huzzah!

[The Anti-Targ]

2 hours ago, polishgenius said:

If I've understood everything correctly, it's in a transfer orbit, ie an elliptical one that'll take it to L2, at which point it'll use its own boost to transfer into a halo orbit around L2. 

So it is on its way and doesn't need or want to reach actual escape velocity from Earth before the transfer, no? 

Right you are, it can't just head straight to the L2 point because it would need a shit load of fuel to decelerate when it got there on a point to point journey, so it needs to get there on an orbital path. Will it do an actual orbit of earth or is it just going to be outbound leg only with the final burn being what turns it from an elliptical earth orbit to an L2 orbit (halo orbit they seem to call it).

It does the head in that the telescope's permanent orbit will be circling around a point in empty space.

[maarsen]

6 hours ago, The Anti-Targ said:

Right you are, it can't just head straight to the L2 point because it would need a shit load of fuel to decelerate when it got there on a point to point journey, so it needs to get there on an orbital path. Will it do an actual orbit of earth or is it just going to be outbound leg only with the final burn being what turns it from an elliptical earth orbit to an L2 orbit (halo orbit they seem to call it).

It does the head in that the telescope's permanent orbit will be circling around a point in empty space.

The point is not really empty because the gravitational fields  of the sun  moon and earth more or less balance each other there. I am pretty sure that stuff gets stuck there due to that fact. 

[SpaceChampion]

It's going to a halo orbit circling L2.  This is perpendicular to the plane of the Earth-Moon system, and tangential to the Earth's orbit around the sun.

 

Another by Scott Manley explaining more in depth

 

Edited December 26, 2021 by SpaceChampion

[The Anti-Targ]

12 hours ago, maarsen said:

The point is not really empty because the gravitational fields  of the sun  moon and earth more or less balance each other there. I am pretty sure that stuff gets stuck there due to that fact. 

The moon probably has a negligible gravitational influence on the Legrange points since it's gravitational well will be in constantly moving relative to the Legrange points give it is orbiting the earth while the Legrange points are fixed distances from the Earth.

Imagine JWST reaches L2 and it's orbit is already occupied by thousands of small object that are a physical danger to it. Have they looked to find out if there are any objects hanging out in that area?

[Loge]

14 hours ago, maarsen said:

The point is not really empty because the gravitational fields  of the sun  moon and earth more or less balance each other there. I am pretty sure that stuff gets stuck there due to that fact. 

The gravity of the sun and the earth add up in L2. That allows an object parked there to orbit the sun with the same orbital period as the earth, despite the orbit being larger / wider than the earth's orbit. And of course the sun's gravity is much stronger. An "orbit around L2", which is really a wobble in the orbit around the Sun, is unstable. That's bad insofar as it requires frequent corrections. But it also ensures that it's empty of debris. There are quite a few spacecraft in orbit around L2 already, but those are all known:

https://en.wikipedia.org/wiki/Lagrange_point#Spacecraft_at_Sun–Earth_L2

Edited December 26, 2021 by Loge

[Ser Scot A Ellison]

Just found this site this morning.  It tracks Webb’s current position and status.  I didn’t realize just how far beyond Lunar orbit L2 actually was:

https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?fbclid=IwAR2YGuBZTs0dI__d_aMQUmRvyr9y-Pb10G2eXbTH5_CxyMXFbVq41YkHJ_I

[Loge]

14 minutes ago, Ser Scot A Ellison said:

Just found this site this morning.  It tracks Webb’s current position and status.  I didn’t realize just how far beyond Lunar orbit L2 actually was:

https://www.jwst.nasa.gov/content/webbLaunch/whereIsWebb.html?fbclid=IwAR2YGuBZTs0dI__d_aMQUmRvyr9y-Pb10G2eXbTH5_CxyMXFbVq41YkHJ_I

From earth to L2 is about four times the distance from the earth to the moon.

Edited December 26, 2021 by Loge

[polishgenius]

48 minutes ago, Loge said:

And of course the sun's gravity is much stronger. An "orbit around L2", which is really a wobble in the orbit around the Sun, is unstable. That's bad insofar as it requires frequent corrections.

 

Yup, hence the five-to-ten year scope of the mission - it can only carry so much propellant with it. 

[ithanos]

21 hours ago, Loge said:

The gravity of the sun and the earth add up in L2. That allows an object parked there to orbit the sun with the same orbital period as the earth, despite the orbit being larger / wider than the earth's orbit. And of course the sun's gravity is much stronger. An "orbit around L2", which is really a wobble in the orbit around the Sun, is unstable. That's bad insofar as it requires frequent corrections. But it also ensures that it's empty of debris. There are quite a few spacecraft in orbit around L2 already, but those are all known:

https://en.wikipedia.org/wiki/Lagrange_point#Spacecraft_at_Sun–Earth_L2

From the wiki list only two are still there, Gaia Space and Spektr-RG X-Ray Observatories, with the earlier missions having been decommissioned and put out to heliocentric graveyard orbits - except for Wind.

Launched in 1994, Wind got out to Sun-Earth L2 around 2003-2004 and then headed to Sun-Earth L1 where its been ever since and is expected to last another 50years! Damn, this is the the little spacecraft that could! I can check Wind's orbit from the SPDF page but can't find info on its propulsion and how its been getting around. Need to check if Scott Manley's done a video on Wind.

[Erik of Hazelfield]

Interesting video about the telescope if you didn’t already see it: 

 

[ithanos]

Ok, JWST's sunshield unfolding should begin later today and, touchwood, should be completely unfolded in six days. This, being the most mechanical of JWST's preparation, is what worries Scott Manley the most, fingers crossed indeed. 

[Ser Scot A Ellison]

Shouldn’t we be moving on to unfurling the sun shield?  Are they having difficulties?

[Starkess]

Yes, today was the day the mid-booms were supposed to deploy (basically unrolling the shield). Last update was for the cover removal yesterday. However they've stated multiple times that the timeline is subject to change so I wouldn't panic yet (she says, panicking).

[Ser Scot A Ellison]

27 minutes ago, Starkess said:

Yes, today was the day the mid-booms were supposed to deploy (basically unrolling the shield). Last update was for the cover removal yesterday. However they've stated multiple times that the timeline is subject to change so I wouldn't panic yet (she says, panicking).

I just remember the snagged Galileo High Gain antenna..,

[Ser Scot A Ellison]

The port mid-boom extension is now showing completed.  Next step is starboard mid-boom extension.