BMAONE23 wrote:Had we gone for the Replace Route rather than the Fix It Route as you suggested, we might have had several HST platforms in orbit, but how many fixes were for operational functionality? If the "Fixes" weren't done, we would still, likely as not, have only one functioning HST and several piles of orbiting space junk.
HST can be de-orbited at any time.
Hubble has be hobbled from the beginning by the need to find some practical use for the US manned space program:
http://en.wikipedia.org/wiki/Hubble_Space_Telescope wrote:
<<Hubble is situated in a low-Earth orbit so that it can be reached by the space shuttle for servicing missions, but this means that most astronomical targets are occulted by the Earth for slightly less than half of each orbit. Observations cannot take place when the telescope passes through the South Atlantic Anomaly due to elevated radiation levels, and there are also sizable exclusion zones around the Sun (precluding observations of Mercury), Moon and Earth. The solar avoidance angle is about 50°, which is specified to keep sunlight from illuminating any part of the OTA.
Because Hubble orbits in the upper atmosphere, its orbit changes over time in a way that is not accurately predictable. The density of the upper atmosphere varies according to many factors, and this means that Hubble's predicted position for six weeks' time could be in error by up to 4,000 km. Observation schedules are typically finalized only a few days in advance, as a longer lead time would mean there was a chance that the target would be unobservable by the time it was due to be observed.
In early 1986, the planned HST launch date of October that year looked feasible, but the Challenger accident brought the U.S. space program to a halt, grounding the space shuttle fleet and forcing the launch of Hubble to be postponed for several years. The telescope had to be kept in a clean room, powered up and purged with nitrogen, until a launch could be rescheduled. This costly situation (about $6 million per month) pushed the overall costs of the project even higher. On the other hand, engineers used this time to perform extensive tests, swap out a possibly failure-prone battery, and make other improvements. Furthermore, the ground software needed to control Hubble was not ready in 1986, and in fact was barely ready by the 1990 launch. Eventually, following the resumption of shuttle flights in 1988, the launch of the telescope was scheduled for 1990. On 24 April 1990, shuttle mission STS-31 saw Discovery launch the telescope successfully into its planned orbit. From its original total cost estimate of about $400 million, the telescope had by now cost over $2.5 billion to construct. Hubble's cumulative costs up to this day are estimated to be several times higher still, with US expenditure estimated at between $4.5 and $6 billion, and Europe's financial contribution at €593 million.>>
http://en.wikipedia.org/wiki/James_Webb_Space_Telescope wrote:
<<As of the 2005 re-plan, the life-cycle cost of the James Webb Space Telescope (JWST) project was estimated at about $4.5 billion. This comprises approximately $3.5 billion for design, development, launch and commissioning, and approximately $1.0 billion for ten years of operations. ESA is contributing about €300million, including the launch, and the Canadian Space Agency about $39M Canadian. As of May 2007[update] costs were still on target.>>
[quote="BMAONE23"]Had we gone for the Replace Route rather than the Fix It Route as you suggested, we might have had several HST platforms in orbit, but how many fixes were for operational functionality? If the "Fixes" weren't done, we would still, likely as not, have only one functioning HST and several piles of orbiting space junk.[/quote]
HST can be de-orbited at any time.
Hubble has be hobbled from the beginning by the need to find some practical use for the US manned space program:
[quote=" http://en.wikipedia.org/wiki/Hubble_Space_Telescope"]
<<Hubble is situated in a low-Earth orbit so that it can be reached by the space shuttle for servicing missions, but this means that most astronomical targets are occulted by the Earth for slightly less than half of each orbit. Observations cannot take place when the telescope passes through the South Atlantic Anomaly due to elevated radiation levels, and there are also sizable exclusion zones around the Sun (precluding observations of Mercury), Moon and Earth. The solar avoidance angle is about 50°, which is specified to keep sunlight from illuminating any part of the OTA.
Because Hubble orbits in the upper atmosphere, its orbit changes over time in a way that is not accurately predictable. The density of the upper atmosphere varies according to many factors, and this means that Hubble's predicted position for six weeks' time could be in error by up to 4,000 km. Observation schedules are typically finalized only a few days in advance, as a longer lead time would mean there was a chance that the target would be unobservable by the time it was due to be observed.
In early 1986, the planned HST launch date of October that year looked feasible, but the Challenger accident brought the U.S. space program to a halt, grounding the space shuttle fleet and forcing the launch of Hubble to be postponed for several years. The telescope had to be kept in a clean room, powered up and purged with nitrogen, until a launch could be rescheduled. This costly situation (about $6 million per month) pushed the overall costs of the project even higher. On the other hand, engineers used this time to perform extensive tests, swap out a possibly failure-prone battery, and make other improvements. Furthermore, the ground software needed to control Hubble was not ready in 1986, and in fact was barely ready by the 1990 launch. Eventually, following the resumption of shuttle flights in 1988, the launch of the telescope was scheduled for 1990. On 24 April 1990, shuttle mission STS-31 saw Discovery launch the telescope successfully into its planned orbit. From its original total cost estimate of about $400 million, the telescope had by now cost over $2.5 billion to construct. Hubble's cumulative costs up to this day are estimated to be several times higher still, with US expenditure estimated at between $4.5 and $6 billion, and Europe's financial contribution at €593 million.>>[/quote]
[quote=" http://en.wikipedia.org/wiki/James_Webb_Space_Telescope"]
<<As of the 2005 re-plan, the life-cycle cost of the James Webb Space Telescope (JWST) project was estimated at about $4.5 billion. This comprises approximately $3.5 billion for design, development, launch and commissioning, and approximately $1.0 billion for ten years of operations. ESA is contributing about €300million, including the launch, and the Canadian Space Agency about $39M Canadian. As of May 2007[update] costs were still on target.>>[/quote]