Hubble servicing mission 4 status (title edited) - Page 2

ToSeek · #31 (**permalink**) 12-July-2006, 03:57 PM

James Webb isn't actually a replacement, even though it's being billed as such. It's intended to focus on the infrared part of the spectrum, while Hubble deals mostly with visible light.

And even if it were a replacement, Hubble is oversubscribed by something like a factor of 5 (ngc3314 can probably provide an exact figure). You could have five Hubbles up there, and astronomers could keep them all busy.

ngc3314 · #32 (**permalink**) 12-July-2006, 05:24 PM

Quote:

Originally Posted by ToSeek

James Webb isn't actually a replacement, even though it's being billed as such. It's intended to focus on the infrared part of the spectrum, while Hubble deals mostly with visible light.

And even if it were a replacement, Hubble is oversubscribed by something like a factor of 5 (ngc3314 can probably provide an exact figure). You could have five Hubbles up there, and astronomers could keep them all busy.

Oversubscription factors for Hubble have generally been 5-7 depending on the year (new instruments generate spikes of demand).

JWST has less overlap in capability with HST than was once planned - to reduce cost overruns, much potential visible-light capability and image quality have been sacrificed to protect the core IR capability. The IR is particularly valuable for the triple questions driving much of the JWST design - formation of galaxies, formation of stars, formation of planets.

antoniseb · #33 (**permalink**) 12-July-2006, 09:17 PM

That is a sad point. I'd looked forward to getting even higher resolution images from JWST. Now, that being said, I am still VERY enthusiastic about seeing the things that JWST will image for us, including some deep fields on the far infrared showing galaxies that cannot be seen in visible light.

JWST may end up showing us which epoch is the beginning of galaxy large-scale star forming.

Wolf-S · #34 (**permalink**) 13-July-2006, 03:56 PM

"NASA extends rescue missions on manifest"

Quote:

The latest Shuttle manifest shows NASA has extended the number of flights that will have a LON (Launch On Need) rescue mission on standby.
While STS-121 with Discovery has stood down its STS-300 LON (with Atlantis), three more rescue missions have been added to accompany flights through to at least STS-120, with another special - and very different - LON mission being considered for STS-125's Hubble Servicing Mission.

http://www.nasaspaceflight.com/content/?cid=4626

joema · #35 (**permalink**) 13-July-2006, 07:20 PM

Quote:

Originally Posted by antoniseb

That is a sad point. I'd looked forward to getting even higher resolution images from JWST...

Don't be too sad. It's possible by the time JWST is operational, further advances in ground-based adaptive optics and optical imaging interferometry may allow Hubble-type (or better) resolution from ground-based telescopes.

I don't know at what point Hubble's unique combination of resolution, viewing angle and limiting magnitude will be reached, but technology is marching on.

antoniseb · #36 (**permalink**) 13-July-2006, 07:42 PM

Quote:

Originally Posted by joema

I don't know at what point Hubble's unique combination of resolution, viewing angle and limiting magnitude will be reached, but technology is marching on.

I am aware of this, though there are people who claim that adaptive optics and other advances can *never* get beyond certain resolutions, or abilities to separate close light sources.

joema · #37 (**permalink**) 13-July-2006, 08:03 PM

Quote:

Originally Posted by antoniseb

...there are people who claim that adaptive optics and other advances can *never* get beyond certain resolutions, or abilities to separate close light sources.

Well, *never* is a pretty strong word, especially when applied to a rapidly advancing technical area. But of course there will always be *certain* limits, but the question is will those limits exceed HST?

The VLTI web site says it will have milli-arcsecond angular resolution when fully operational. http://www.eso.org/projects/vlti/

Backers of the OWL telescope predict it will also have submilliarcsecond angular resolution and a limiting magnitude of 38.

http://www.astrosociety.org/pubs/mer.../ultimate.html

Of course that doesn't necessarily mean at visual wavelengths or over a Hubble-size field of view, but it's obvious progress continues in this area. By the time JWST is launched in 2013 (assuming no further delays), it seems a good bet that adaptive optics and imaging interferometry will be significantly further advanced.

Back on the main topic, it's good news that the HST servicing mission is still on.

Doodler · #38 (**permalink**) 13-July-2006, 10:23 PM

Quote:

Originally Posted by joema

I don't know at what point Hubble's unique combination of resolution, viewing angle and limiting magnitude will be reached, but technology is marching on.

Staring time is the big key with space telescopes.

tofu · #39 (**permalink**) 13-July-2006, 10:45 PM

Quote:

Originally Posted by Doodler

Staring time is the big key with space telescopes.

But couldn't you stare at something for multiple nights from a ground-based scope?

As to resolution, I've heard people say that adaptive optics make Hubble less important, and I've heard people say we'll never approach Hubble from the ground. One thing is for sure though, we'll never approach JWST's capability from the ground - without blowing away our atmosphere, since the atmosphere absorbes so much IR.

It's too bad that we can't put giant scopes on the Moon.

joema · #40 (**permalink**) 13-July-2006, 10:57 PM

Quote:

Originally Posted by Doodler

Staring time is the big key with space telescopes.

Using HST as an example, staring time is key because (a) it can do it, and (b) it must do it to compensate for the small 2.4 meter apeture.

By comparison the OWL telescope (if built) could capture as much light in 3.5 minutes as the Hubble Ultra Deep Field did in 11 days. The extreme HDF exposure times achieve the desired image, but severely limits the cumulative scientific payload -- it's out of commission for days building that one image, whereas OWL could do many such images per night.

The larger diameters available for terrestrial telescopes reduces the extreme exposure times the smaller space telescopes are forced to use for faint objects.

I mention this not to knock Hubble but in answer to the original post lamenting that the reduction of JWST visible spectrum capability would mean no further resolution improvments beyond HST. It's likely those improvements will eventually happen, only from ground-based instruments, and possibly in the same timeframe as JWST.

Terrestrial telescopes (even in optimal sites) might have a limiting magnitude imposed by background atmospheric "sky glow", but I don't know what that is.

And obviously spectral regions blocked by the atmosphere can only be imaged from space.

ToSeek · #41 (**permalink**) 18-July-2006, 05:08 PM

No decision on mission to Hubble

Quote:

Although the space shuttle Discovery's mission concluded with a safe landing yesterday, NASA Administrator Michael Griffin said he will need until fall to decide whether to authorize another shuttle servicing mission to extend the life of the Hubble Space Telescope. "No one wants to do a Hubble flight more than I," Griffin said yesterday when reminded of his promise last year to authorize a Hubble mission if NASA could complete two safe shuttle flights in the wake of the fatal 2003 Columbia accident.

ToSeek · #42 (**permalink**) 31-July-2006, 03:18 PM

Hubble Puzzle: How Safe is a Shuttle Servicing Mission?

Quote:

Despite the success of NASA’s second shuttle flight since the 2003 Columbia tragedy, the decision to launch astronauts to the Hubble Space Telescope remains uncertain as top agency officials debate its safety.

The shuttle Discovery’s near flawless STS-121 mission this month completed NASA’s return to flight effort and demonstrated that post-Columbia safety improvements appear to be effective.

But NASA chief Michael Griffin said mission managers and engineers must complete a thorough analysis of Discovery’s mission – and launch the upcoming STS-115 flight aboard Atlantis in late August – before deciding whether a Hubble spaceflight is safe to fly.

“No one wants to do a Hubble flight more than I,” Griffin said after Discovery’s six-astronaut crew landed on July 17. “But we do not want to get ahead of ourselves. We want to go about things in the right way.”

ToSeek · #43 (**permalink**) 31-July-2006, 03:34 PM

Two related threads merged.

ToSeek · #44 (**permalink**) 31-July-2006, 03:38 PM

The servicing missions home page is here:

http://hubble.nasa.gov/missions/intro.php

Quote:

The Hubble Space Telescope Program, resident at NASA's Goddard Space Flight Center in Greenbelt, MD, continues to work toward a possible Servicing Mission 4 (SM4) in late-2007 or early-2008.

Prior to an HST SM4 being approved by the NASA Administrator, the Shuttle must perform two consecutive successful flights: STS-114, which flew in July of 2005, and STS-121, which was launched July 4, 2006. An engineering risk analysis also must demonstrate a high degree of safety for the Shuttle and its crew in an SM4 flight to Hubble. Because the study will be partially informed by the STS-121 experience, it will not be completed until some period of time after that mission has landed.

Given the possibility that SM4 might occur as soon as 18-24 months from now, preparations for the mission cannot be delayed until after the Shuttle has demonstrated its robustness in the manner just described. Accordingly, and in response to direction from the NASA Administrator, the Hubble Program has for the last year been proceeding with normal planning and preparations for a possible SM4.

ToSeek · #45 (**permalink**) 01-August-2006, 03:19 PM

NASA evaluates rescue for Hubble mission

Quote:

Details are starting to emerge about potential crew rescue options for the Hubble Servicing Mission (HSM), currently designated STS-125.

NASA Documents, which confirm STS-125 is the HST-SM04 mission, show the flight - currently scheduled to launch with Shuttle Discovery, NET (No Earlier Than) April 11, 2008 - has a rescue mission requirement under evaluation.

BigDon · #46 (**permalink**) 02-August-2006, 03:11 PM

Thanks for the heads up about the OWL telescope! Until this morning I had never heard of it! Now I have something else to look forward too.

Doodler · #47 (**permalink**) 02-August-2006, 05:53 PM

Quote:

Originally Posted by joema

Using HST as an example, staring time is key because (a) it can do it, and (b) it must do it to compensate for the small 2.4 meter apeture.

By comparison the OWL telescope (if built) could capture as much light in 3.5 minutes as the Hubble Ultra Deep Field did in 11 days. The extreme HDF exposure times achieve the desired image, but severely limits the cumulative scientific payload -- it's out of commission for days building that one image, whereas OWL could do many such images per night.

The larger diameters available for terrestrial telescopes reduces the extreme exposure times the smaller space telescopes are forced to use for faint objects.

I mention this not to knock Hubble but in answer to the original post lamenting that the reduction of JWST visible spectrum capability would mean no further resolution improvments beyond HST. It's likely those improvements will eventually happen, only from ground-based instruments, and possibly in the same timeframe as JWST.

Terrestrial telescopes (even in optimal sites) might have a limiting magnitude imposed by background atmospheric "sky glow", but I don't know what that is.

And obviously spectral regions blocked by the atmosphere can only be imaged from space.

I stand very corrected. Thank you.

ToSeek · #48 (**permalink**) 06-September-2006, 05:55 PM

NASA look to move Hubble mission to 2007

Quote:

NASA is evaluating the possibility of moving the final Hubble Space Telescope servicing mission from April 2008, to December 2007 - following a request to the Shuttle Program from the group in charge of the telescope.

STS-125, currently manifested to launch with Shuttle Discovery, will receive final authorisation next month, with plans for a unique LON (Launch On Need) rescue mission also in works.

ToSeek · #49 (**permalink**) 14-September-2006, 04:00 PM

New Hubble Space Telescope Hardware Damaged On The Ground

Quote:

According to NASA sources, last Thursday, an I-bolt supporting a lifting rig failed while off-loading the Wide-field Scientific Instrument Protective Enclosure (WSIPE) dropping the rig onto the WSIPE.
...
While NASA has not formally approved a shuttle mission to visit Hubble, NASA Administrator Mike Griffin told NASA employees at GSFC on Tuesday that he'd be making a decision no later than 1 November 2006.