Detailed here...

They got the notice out a full 26 minutes before the media call-in time for questions so I didn't get to listen in Did anybody else manage to call in?

--Emily

<clink!!!> Looks like at least a one-year loss of service for ACS...plus, the article says that they don't plan to replace the ACS due to "enhanced capabilities" of other systems. Why don't I buy that statement completely?

Well, that could be true. But I'm also not clear on whether this problem is internal to ACS or in a separate electronics package that could be replaced or fixed.

That's true as well, Steve, and maybe I'm jumping the gun here....don't know how modular the Hubble instruments are, but I do suspect that they all have internal power supplies designed to operate off of a bus feed. Hope I'm wrong and that there's an easy fix.

From the article, though, it sounds as if there was an internal short @ the ACS power supply, and that probably can't be corrected by anything less than replacing the instrument...bummer.

Yes, I listened in and also recorded it too, but the output was so loud (peaking at +12 dB!) that it was badly distorted.

However, I made some notes during the briefing:

Total loss of Side B electronics (fuse blown)

ACS is now running on Side A electronics in order to maintain thermal control

WFC and HRC cannot be restored on Side A since the Side A CCD Electronics Box stopped working in June 2006 (and the reason why ACS was switched to Side B)

SBC has separate power supply and likely will be restored in mid-Feb in order to support New Horizons (SBC was regularly monitoring Jupiter and Saturn's auroral activity in the FUV)

SM4 is still targeted for Sep 2008 and will not be brought forward by this issue

SM4 will not repair ACS since the electronics control box is difficult for the astronauts to access (they would have to remove the NICMOS cryocooler control system, power off other systems etc. to reach ACS electronics) - that would take two days out of the five available - not worth deleting other tasks to do that - besides the new instrument WFC3 will largely replace ACS capability

SM4 team will take heed of any review board recommendations concerning power supply issues that may affect WFC3 and COS in the same way

Loss of capability after SM4:

ACS WFC was optimized for far-red (600-900 nm) - WFC3 is better in the UV but poorer in the far-red - WFC3 would have to double exposure times to reach same depth as ACS/WFC UDF - however interest in far-red studies is waning amongst astronomy community (interest is now in Near-IR high-z studies)

HRC coronagraph most flexible and powerful ever used on HST - SM4 hope to restore STIS which has good coronagraph for protoplanetary disk studies - but not as good as HRC which opened up a whole new field of study

Del Palmer, thank you so much for these notes!

Just checking on the acronyms:
ACS = Advanced Camera for Surveys (the boken one)
WFC = Wide Field Planetary Camera 2 (works fine)
SBC = ?
FUV = Far Ultraviolet
SM4 = Hubble Servicing Mission 4, currently planned for September 2008
NICMOS = Near Infrared Camera Multi-Object Spectrograph (works fine)
WFC3 = Wide Field Planetary Camera 3, to be added to Hubble in servicing misson
COS = Cosmic Origins Spectrograph, to be added to Hubble in servicing mission
WFC UDF = ?

You said you recorded it? If you could provide me with the recording I could host it on the Planetary Society site for everybody to listen...

--Emily

There's a useful update over at badastronomy.com.

--Emily

WFC = Wide Field Channel (of ACS - busted)
SBC = Solar Blind Channel ((possibly) the only channel of ACS still working)
UDF = Ultra Deep Field?

James

EDIT: and you didn't mention: HRC = High-Resolution Channel (also gone)

WFC is the Wide Field Camera subsystem of ACS; WFPC2 is the Wide Field Planetary Camera 2 (pronounced "wif-pic".) WFC3 is the new instrument to be installed on the next servicing mission.

SBC is the ACS Solar Blind Channel.

WFC UDF is the Ultra-Deep Field taken with WFC.

The press release left out the STIS, which is still functioning...So here is a rundown of the working instruments -

NICMOS - Near Infrared Camera/Multi-Object Spectrometer
STIS - Space Telescope Imaging Spectrograph
FGS - Fine Guidance Sensors (for engineering, but also used for astrometry and photometry0
WF/PC-2 - Wide Field/Planetary Camera 2 - this is getting confused with the ACS's WFC

Ted

P.S. For planet-heads, such as us, this is a really big deal. The WF/PC-2's wide field camera is the best for closeup planetary shots - most famous Hubble planetary shots are from its PC camera (PC= Planetary Camera). Because the ACS HRC can take higher resolution shots (although it has down side of not getting Jupiter/Saturn's ring all in one field and, in the case of Mars, can't take a shot when it is at its closest without the coronograph finger blocking a bit - although I don't think that this will be a problem again until the close apparitions in about a decade), WF/PC-2's replacement lacks a high-resolution planetary camera, and is instead focused on wide field coverage. Given the nature of Hubble's focal plane set-up, all of the wide field cameras have slightly offset from the other instruments, and have been designed accordingly. Hence, on could not simply remove a broken ACS to install the new camera. WF/PC-2 has to go, or its replacement can't be installed (which isn't going to happen). All the more reason to bite our nails!

Just got a quicky one from Lars Christensen:

"There are are good chances that the Solar Blind Channel of ACS can be recovered. The WFC (Wide Field Channel, the most used one) and HRC (High-Resolution Channel) will most likely not be recovered."

Still, I wonder what he means by not recovered...not recovered by what they are doing now, or can't be recovered by a servicing mission.

By the way, I have come to realize something....While the WFC3, to be installed next servicing mission, has no planetary camera, its wide field array - wider than WFPC/2 - has a resolution of .040 arc seconds/pixel in UV/VIS/Very near IR, compared with WFPC/2's planetary camera, which as a resolution of .046 arc seconds/ pixel! WFC3 also has .13 arc/second per pixel resolution in infrared, extending nearly through about two thirds of the wavelengths that NICMOS covers. For a comparison, the WFC on the ACS has a much narrower field of view and .05 arc seconds/pixel resolution. The HRC has .027 arc/second per pixel resolution, which is sometimes improved upon using super-resolution techniques (lots of short exposures taken at slightly different pointings added up to make the full exposure, rather than one long exposure). The SBC has .032 pixels/arc second resolution, but can only be used for faint objects without overexposure.

So, it is very important to recover ACS if at all possible. But, fortunately, for planet folks, it doesn't look like we will be without the coverage we have gotten used to over the past 12 years or so (an exciting side, at least to me, about using WFC3 for planetary coverage, is the increased chance that moons will not escape the high resolution zone).

I believe it is a permanent loss...

John Spencer has another excellent glog entry, this one relating to Hubble.

STIS is very much dead, has been since 2004.

John,

That’s quite an exciting ride you recount with the Hubble. ACS is out, but WFPC2 is still trucking, and now you even have more time. Hats off to you and your team for buckling down to meet the incredibly sudden deadline!

I was curious about the magnitude of new time that your team picked up and how well it’s spaced out. Best I can tell, one full orbit of the Hubble Space Telescope around the Earth is just over 1.5 hours. Of course, half of that time is also not usable for planetary science because Hubble moves behind Earth relative to its target.

Twenty new orbits give you an upper limit of 16 hours of undivided time, not taking into account atmosphere interference when rounding the limb, unusable observation periods like that over the South Atlantic Anomaly, etc. That’s a lot of time with HST, but you would burn through the entire set in 32 hours if they were taken consecutively!

So could you put this “gift” into perspective for us? [The HST Weekly Timetable Reports are not so great for search queries.] How many orbits were you able to get originally with ACS through the competitive grant process? And over what time period are you able to use this new observation time?

Good luck!