|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
James Webb telescope
1.5M miles. God help them if it needs a service mission.
http://news.bbc.co.uk/2/hi/americas/6645179.stm |
#2
|
|||
|
|||
James Webb telescope
Rich wrote:
1.5M miles. God help them if it needs a service mission. They know that... So did the people who put Chandra, XMM-Newton, WMAP, and Spitzer way beyond low Earth orbit as well. And IUE before that - servicing has been a real possibility for only one telescope, and that was as much political heritage as a purely engineering decision. Bill Keel |
#3
|
|||
|
|||
James Webb telescope
Isaac isolated the solar system from the rest of the Universe in
trying to force his terrestrial ballistics agenda into Keplerian orbital geometry - "Cor. 2. And since these stars are liable to no sensible parallax from the annual motion of the earth, they can have no force, because of their immense distance, to produce any sensible effect in our system. Not to mention that the fixed stars, every where promiscuously dispersed in the heavens, by their contrary actions destroy their mutual actions, by Prop. LXX, Book I." Newton As the solar system has a galactic orbital motion,it stands to reason that the influence of the solar system's gactic orbital motion in one direction around the Milky Way axis affects heliocentric orbital geometries as the forward galactic orbital motion of the Sun combined with the heliocentric orbital motion of the Earth whichj spends 6 months traveling in the direction of galactic orbital motion and 6 months against that galactic orbital motion may,I repeat,may generate Keplerian orbital geometries. Of course you lock yourselves in the celestial sphere bubble of Newton and the exotic offshoots and never get to consider the compound orbital motions of the Earth. On May 11, 5:52 pm, Sam Wormley wrote: Rich wrote: 1.5M miles. God help them if it needs a service mission. http://news.bbc.co.uk/2/hi/americas/6645179.stm No spacecraft locate in the vicinity of L2 are intended to be serviced. The either work or they don't. Lagrange Points http://scienceworld.wolfram.com/phys...ngePoints.html http://en.wikipedia.org/wiki/Lagrange_points#Stability The first three Lagrangian points are technically stable only in the plane perpendicular to the line between the two bodies. This can be seen most easily by considering the L1 point. A test mass displaced perpendicularly from the central line would feel a force pulling it back towards the equilibrium point. This is because the lateral components of the two masses' gravity would add to produce this force, whereas the components along the axis between them would balance out. However, if an object located at the L1 point drifted closer to one of the masses, the gravitational attraction it felt from that mass would be greater, and it would be pulled closer. (The pattern is very similar to that of tidal forces.) Although the L1, L2, and L3 points are nominally unstable, it turns out that it is possible to find stable periodic orbits around these points, at least in the restricted three-body problem. These perfectly periodic orbits, referred to as "halo" orbits, do not exist in a full n-body dynamical system such as the solar system. However, quasi-periodic (i.e. bounded but not precisely repeating) orbits following Lissajous curve trajectories do exist in the n-body system. These quasi-periodic Lissajous orbits are what all Lagrangian point missions to date have used. Although they are not perfectly stable, a relatively modest effort at station keeping can allow a spacecraft to stay in a desired Lissajous orbit for an extended period of time. It also turns out that, at least in the case of Sun-Earth L1 missions, it is actually preferable to place the spacecraft in a large amplitude (100,000-200,000 km) Lissajous orbit instead of having it sit at the Lagrangian point, because this keeps the spacecraft off the direct Sun-Earth line and thereby reduces the impacts of solar interference on the Earth-spacecraft communications links. Another interesting and useful property of the collinear Lagrangian points and their associated Lissajous orbits is that they serve as "gateways" to control the chaotic trajectories of the Interplanetary Transport Network. |
#4
|
|||
|
|||
James Webb telescope
On May 11, 10:30 am, Rich wrote:
1.5M miles. God help them if it needs a service mission. http://news.bbc.co.uk/2/hi/americas/6645179.stm Rich, NASA is also working on robotic repair satellites. These would fly between observing and weather satellites making repairs, replacing power supplies and upgrade systems. This is a pretty common sense idea - one that you would have thought would have been pursed earlier in the space program. - Canopus56 |
#5
|
|||
|
|||
James Webb telescope
Hi,
At my last day job at Northrop Grumman, I was the lead optical designer/analyst for the James Webb Space Telescope (NGST at the time) working with on the proposal and later with the Telescope prime, Ball Aerospace. They are acutely aware of the fact that only the Enterprise NCC 1701D will be able to service the telescope at its Lagrange point and (trust me on this one) everything is being done so as to not repeat the HUBBLE PIE eating episode which NASA experienced. If they blow this, there will be very top level careers on the line at a large number of organizations and it will be a joke told for hundreds of years. Jim Klein Rich wrote: 1.5M miles. God help them if it needs a service mission. http://news.bbc.co.uk/2/hi/americas/6645179.stm James E. Klein Engineering Calculations http://www.ecalculations.com Engineering Calculations is the home of the KDP-2 Optical Design Program for Windows. 1-818-507-5706 (Voice and Fax) 1-818-823-4121 "KDP2, not quite easy enough for a Caveman to use" :-) |
#6
|
|||
|
|||
James Webb telescope
canopus56 wrote:
On May 11, 10:30 am, Rich wrote: 1.5M miles. God help them if it needs a service mission. http://news.bbc.co.uk/2/hi/americas/6645179.stm Rich, NASA is also working on robotic repair satellites. These would fly between observing and weather satellites making repairs, replacing power supplies and upgrade systems. This is a pretty common sense idea - one that you would have thought would have been pursed earlier in the space program. - Canopus56 Never underestimate the short sightedness at NASA. Jim James E. Klein Engineering Calculations http://www.ecalculations.com Engineering Calculations is the home of the KDP-2 Optical Design Program for Windows. 1-818-507-5706 (Voice and Fax) 1-818-823-4121 "KDP2, not quite easy enough for a Caveman to use" :-) |
#7
|
|||
|
|||
James Webb telescope
"canopus56" wrote: Rich, NASA is also working on robotic repair satellites. These would fly between observing and weather satellites making repairs, replacing power supplies and upgrade systems. This is a pretty common sense idea - one that you would have thought would have been pursed earlier in the space program. - Canopus56 NASA has long desired to have such capability, but the enabling technology is only recently allowing it to finally happen. Witness ASTRO and NextSat, doing their servicing thing right now: http://science.nasa.gov/headlines/y2...ar_nohands.htm http://www.darpa.mil/orbitalexpress/...n_updates.html http://www.darpa.mil/orbitalexpress/on_orbit_pics.html |
#8
|
|||
|
|||
James Webb telescope
On May 11, 8:17 pm, Jim Klein wrote:
Hi, At my last day job at Northrop Grumman, I was the lead optical designer/analyst for the James Webb Space Telescope (NGST at the time) working with on the proposal and later with the Telescope prime, Ball Aerospace. They are acutely aware of the fact that only the Enterprise NCC 1701D will be able to service the telescope at its Lagrange point and (trust me on this one) everything is being done so as to not repeat the HUBBLE PIE eating episode which NASA experienced. If they blow this, there will be very top level careers on the line at a large number of organizations and it will be a joke told for hundreds of years. They'll just change their name, like the people who made the Hubble mirror did, and they likely won't pay for the mistake. |
#9
|
|||
|
|||
James Webb telescope
On May 11, 6:17 pm, Jim Klein wrote:
At my last day job at Northrop Grumman, I was the lead optical designer/analyst for the James Webb Space Telescope (NGST at the time) working with on the proposal and later with the Telescope prime, Ball Aerospace. Jim, Thanks for the in-the-know insider view. We are all looking forward to many years of great images from the Webb, as we have had from the Hubble. Too bad there isn't enough of a window to re- engineer the Webb to have exchangeable components that could be robotically removed and replaced. - Kurt |
#10
|
|||
|
|||
James Webb telescope
On May 11, 12:52 pm, Sam Wormley wrote:
Rich wrote: 1.5M miles. God help them if it needs a service mission. http://news.bbc.co.uk/2/hi/americas/6645179.stm No spacecraft locate in the vicinity of L2 are intended to be serviced. The either work or they don't. Imagine then the original Hubble sitting out there... |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
James Webb Space Telescope looks out of this world (Forwarded) | Andrew Yee | News | 0 | January 16th 07 10:07 PM |
James Webb Space Telescope is a boondoggle | Andrew Nowicki | Astronomy Misc | 38 | February 24th 05 06:48 AM |
James Webb Space Telescope is a boondoggle | Andrew Nowicki | Policy | 37 | February 24th 05 06:48 AM |
James Webb Space Telescope maintenance | Andrew Nowicki | Science | 1 | June 5th 04 06:32 PM |
James Webb Space Telescope | Alan Erskine | Policy | 7 | February 9th 04 11:16 PM |