Date: Thu, 18 Feb 93 05:06:41 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V16 #197 To: Space Digest Readers Precedence: bulk Space Digest Thu, 18 Feb 93 Volume 16 : Issue 197 Today's Topics: FGS Info (RE: HST repair mission) Nobody cares about Fred? PEGASUS QUESTION (2 msgs) Space Icons Welcome to the Space Digest!! Please send your messages to "space@isu.isunet.edu", and (un)subscription requests of the form "Subscribe Space " to one of these addresses: listserv@uga (BITNET), rice::boyle (SPAN/NSInet), utadnx::utspan::rice::boyle (THENET), or space-REQUEST@isu.isunet.edu (Internet). ---------------------------------------------------------------------- Date: Wed, 17 Feb 1993 18:15:20 GMT From: reinhard@stsci.edu Subject: FGS Info (RE: HST repair mission) Newsgroups: sci.space In article <1ltbl9INNet@access.digex.com>, prb@access.digex.com (Pat) writes: > In article <1993Feb14.142749.2901@ke4zv.uucp> gary@ke4zv.UUCP (Gary Coffman) writes: >>half smiley, look up GE's TIMs program.) As to software, I don't know >>which instrument is responsible for fine pointing, but if it is one >>that is left off of Jr, then some redesign is definitely required. >> > > > Guidance comes from thhe Fine guidance system. A series of three banana > shaped ccd, which tap light off the WF/PC? My understanding is the > FGS is considered almost a separate science instrument on it's own. > > The Fine Guidance Sensors (FGS) are located in the focal plane structure and placed at right angles to the optical path of the telescope. They have "pick-off" mirrors that deflect the incoming light into the apertures. Each of the three apertures cover a 90 degree sector of the telescope's outer portion of the field of view. Each of the sensors have a large 60 arcmin^2 field of view to search for and track stars. These fields do not interfere or overlap with any of the other instruments. Once the two target-acquisition FGSs lock onto guide stars, the third FGS can perform astrometric operations on targets within the field of view of that FGS. This is how they can be used as a separate science instrument. Kent Reinhard Space Telescope Science Institute ------------------------------ Date: 17 Feb 93 21:21:34 GMT From: "Allen W. Sherzer" Subject: Nobody cares about Fred? Newsgroups: sci.space In article <1lu78iINNkcv@mojo.eng.umd.edu> sysmgr@king.eng.umd.edu writes: >>Now before Doug whines about Intelsat, if NASA had engaged in such a >>program of practice he would have a point. They didn't and he doesn't. >First you whine about the Intelsat rescue. "No value," he says, "Cheaper to >send up a new satellite." Which was correct. NASA rescued the satellite because they thought it would be good PR. If they thought (as they should have) that EVA was important they would have been doing far more of it a long time ago. That is why I said you would have a legitimate point *IF* NASA was engaged in regular EVA. In fact, even here it is a bit strained. It turns out that the astronauts say they where so busy with the work they didn't have time to try and learn from the experience. >During the course of the mission, they find there ARE some differences between >ground simulations and The Real Thing. >So, NASA adds EVA time whenever it can on future Shuttle missions. Too little too late. I assume from past postings Doug, that you are not an engineer or at best a student so I'll explain why this is important. In design it is inevitable that mistakes will be made. It also turns out that the later mistakes are found, the more expensive it is to fix those mistakes. Therefore good engineers spend a lot of effort finding errors as soon as possible. Now with a large space station requiring several times the existing EVA experience base to assemble, assembly itself becomes a large risk area. The prudent thing to do is to begin very early in the project conducting LOTS of experiments on orbit and coorelating them with ground based efforts (like water tank simulations and task models). NASA failed to do this and now it is starting to look like there may (suprise suprise) be more problems than NASA anticipated. Instead of anticipating problems early on, they wait for the end of the project. This is one reason why the station is so expensive. Better risk reduction up front and we would have had a station we can afford. >NASA realizes it has some shortcomings. It now does EVAs and people such as >yourself start bitching about how useless it is to have two astronauts haul each >other around in the Shuttle cargo bay. At this stage in the game, it is indeed too late. In 1984, that would have been a great experiment to try. I applaud these initial experiments they are doing but it should be obvious that they should have done more sooner. Asking why in hell it took so long to do the obvious is a reasonable question. >So tell me, Mr. Sherzer, what is the REAL reason why you don't like NASA? Parts of NASA I like a lot. When I was in aerospace I read a lot of the NASA aeronautical work. It was all first rate stuff and we are far better for it. Manned space (which I think is very important) doesn't spend my money very wisely. Examples abound; asside from Shuttle and Fred we can look at: 1. The wake shield facility. NASA cost models say it should cost $93 million to build. A private company is building the exact same thing for $11 million. 2. Spacehab. NASA costing says it should cost $1.12 billion. A private company is building the exact same thing for $115 million. 3. DCX. NASA says eight years and about a billion $$. MacDac says $60 million and two years. >Were you denied a job there? Never applied to NASA. I was offered a space station job (at a 15% increase in pay) but turned it down. No, I'm not upset because I didn't get a job. >Astronaut slot? Again, no. I would have been a good pilot (95+ percentile on the Air Force Pilot Aptitude Test) but my eyes are terrible. So I have never applied. I long ago accepted that I will never fly spacecraft or high performance aircraft. No regrets. >It is obvious you have an axe to >grind, beause they're incapable of meeting your standards of perfection. I am holding them to the 'reasonable man' standard, not perfection. I think the abuses described above are very good reasons not to like the job NASA is doing and to expect a lot better. Why don't you? Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "A great man is one who does nothing but leaves | | aws@iti.org | nothing undone" | +----------------------118 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 17 Feb 93 19:18:51 GMT From: clifford bettis Subject: PEGASUS QUESTION Newsgroups: sci.space kjenks@gothamcity.jsc.nasa.gov writes: >Lawrence Curcio (lc2b+@andrew.cmu.edu) wrote: >: [...] while taking advantage of at least some of airplane's velocity. >Although pointing the vehicle in the right direction helps somewhat, >adding a couple of hundred kph doesn't really do you that much good. >The airplane's velocity is not a sizeable fraction of orbital >velocity. I disagree very much. Starting a rocket from a moving start does wonders for its final velocity. If I recall correctly, there have been schemes for putting a rocket on wheels and rolling it down a u-shaped track and firing up the engines at its lowest point. People often object that one shouldn't gain anything by this since whatever you gain in kinetic energy you lose in potential energy. But one must remember that a rocket has to carry its fuel along with it and as measured from the earth produces a lot more horse power when its moving with respect to the earth (even though the thrust is the same). Cliff Bettis cbettis@unlinfo.unl.edu ------------------------------ Date: Wed, 17 Feb 1993 19:31:32 GMT From: Paul Dietz Subject: PEGASUS QUESTION Newsgroups: sci.space In article <1lu32rINN3t1@crcnis1.unl.edu> cbettis@unl.edu (clifford bettis) writes: >> Although pointing the vehicle in the right direction helps somewhat, >> adding a couple of hundred kph doesn't really do you that much good. >> The airplane's velocity is not a sizeable fraction of orbital >> velocity. > I disagree very much. Starting a rocket from a moving start does > wonders for its final velocity. If I recall correctly, there have been > schemes for putting a rocket on wheels and rolling it down a u-shaped > track and firing up the engines at its lowest point. Perhaps more significant for airlaunch than the rather small velocity gain is the lower atmospheric pressure. This enables one to put a larger nozzle on the first stage, improving Isp, or operate the first stage at lower pressure, reducing the weight of the casing (for solids). Paul F. Dietz dietz@cs.rochester.edu ------------------------------ Date: Wed, 17 Feb 1993 17:53:10 GMT From: kjenks@gothamcity.jsc.nasa.gov Subject: Space Icons Newsgroups: sci.space JSEXTON@UNCA.EDU wrote: : I have several astronomy and Space related files in Windows,that : were without icons.I'd like to get some icons to use for them and wonder : if anyone can tell me where I can obtain some, either by FTP or a : program offered by some company? I maintain an archive of space-related graphics on the anon-FTP server at ames.arc.nasa.gov. Take a look at: ames.arc.nasa.gov:/pub/SPACE/LOGOS/README -- Ken Jenks, NASA/JSC/GM2, Space Shuttle Program Office kjenks@gothamcity.jsc.nasa.gov (713) 483-4368 "...back to the moon, back to the future, and, this time, back to stay." -- George Bush ------------------------------ From: Bill Higgins-- Beam Jockey Newsgroups: sci.space Subject: Dogs and Mice (was Re: Book Computers/AI in Shuttle-SSF) Message-Id: <1993Feb17.130058.1@fnalf.fnal.gov> Date: 17 Feb 93 07:00:58 GMT Article-I.D.: fnalf.1993Feb17.130058.1 References: <1993Feb13.230142.1@acad3.alaska.edu> <1993Feb17.165953.3546@aio.jsc.nasa.gov> Organization: Fermi National Accelerator Laboratory Lines: 19 Nntp-Posting-Host: fnalf.fnal.gov Sender: news@CRABAPPLE.SRV.CS.CMU.EDU Source-Info: Sender is really isu@VACATION.VENARI.CS.CMU.EDU In article <1993Feb17.165953.3546@aio.jsc.nasa.gov>, kjenks@gothamcity.jsc.nasa.gov writes: > Our safety guys get > all worried about laser light blinding astronauts. (I could tell > stories about the problems getting an optical mouse flown inside the > crew compartment. The safety gang went a little bonkers about the > brightness of the LED inside the mouse.) This suggests that the old Groucho Marx quote: "Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read." may not be true for mice. Bill Higgins, Beam Jockey | Comet Swift-Tuttle is Fermi National Accelerator Laboratory | Mama Nature's way of Bitnet: HIGGINS@FNAL.BITNET | saying it's time to Internet: HIGGINS@FNAL.FNAL.GOV | get off the planet. SPAN/Hepnet: 43011::HIGGINS | --Dale Amon ------------------------------ End of Space Digest Volume 16 : Issue 197 ------------------------------