Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from beak.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Sat, 30 Jun 1990 01:53:50 -0400 (EDT) Message-ID: <4aX3tA-00VcJM1JE4n@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Sat, 30 Jun 1990 01:53:16 -0400 (EDT) Subject: SPACE Digest V11 #586 SPACE Digest Volume 11 : Issue 586 Today's Topics: Payload Status for 06/28/90 (Forwarded) Re: Venus Re: RL-10 ignition (was Re: SSME Ignition from sci.space.shuttle) Re: What Spherical Aberration is Re: What Spherical Aberration is Re: Unofficial HST report - aberration problem Galileo Update - 06/28/90 Re: HST focus problem Re: Model rocket launchers Re: SpaceList Venus Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription notices, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: 28 Jun 90 20:19:17 GMT From: trident.arc.nasa.gov!yee@ames.arc.nasa.gov (Peter E. Yee) Subject: Payload Status for 06/28/90 (Forwarded) Daily Status/KSC Payload Management and Operations 06-28-90. - STS-35 ASTRO-1/BBXRT (at OPF) - Experiment monitoring continues. A video probe search for a lost piece of safety wire will also be performed today. - STS-37 GRO (at PHSF) - Functional testing continues. - STS-40 SLS-1 (at O&C) - CITE testing will be active today. - STS-41 Ulysses (at Hanger AO) - Ulysses functional testing continues. At the VPF, landlines will be validated and GSE will be staged today. - STS-42 IML-1 (at O&C) - Rack, floor, and module staging is continuing. - Atlas-1 (at O&C) - RAU mating plates, EPDB brackets, and pallet cables will be installed today. The orthogrid lifting fixture will be removed. - STS-46 TSS-1 (at O&C) - Closeout inspections continue. - STS-47 Spacelab-J (at O&C) - Rack 5, 7 and 11 staging continues on second shift. - HST M&R - ------------------------------ Date: 29 Jun 90 04:52:00 GMT From: pgf@athena.mit.edu (Peter G. Ford) Subject: Re: Venus In article <5839@aplcen.apl.jhu.edu> jwm@aplvax.jhuapl.edu (Jim Meritt) writes: >Anyone happen to know the temperature & presssure on Ishtar Terra (the >"mesa" on Venus's north polar region that is about the size of the US >and two miles high? There's a wide variation of altitude across Ishtar. The following table is taken from "Kliore, A. J., V. I. Moroz, and G. M. Kesting, The Venus international reference atmosphere, Adv. Space Res. 5, no. 11, 1985, Pergamon Press. (also: COSPAR Report JPL-D-2216)." Altitude Temp Pressure (km) (K) (bars CO2) Feature --------------------------------------------------------------------------- 0 743.0 98.12 "Average" lowland plains +3 720.2 81.09 Southern Lakshmi Planum +4 712.4 76.01 Northern Lakshmi Planum +7 688.8 62.35 Summits, Akna & Freya Montes +13 643.2 41.12 Summit, Maxwell Mons --------------------------------------------------------------------------- Since no probes have landed there yet, the table is based on (a) Pioneer-12 altimeter measurements of planetary radius, (b) Pioneer-12, Venera, and Vega lander measurements of surface temperature and atmospheric pressure, (c) measurements of atmospheric pressure from Venera and Pioneer Venus radio occultation, and (d) temperature extrapolation assuming an adiabatic CO2 atmosphere. ---------------------- Peter Ford MIT & Magellan Project ------------------------------ Date: 27 Jun 90 14:34:08 GMT From: serre@boulder.colorado.edu (SERRE GLENN) Subject: Re: RL-10 ignition (was Re: SSME Ignition from sci.space.shuttle) A couple facts about the RL-10 (this is in response to a mention of RL-10s in the SSME ignition thread in sci.space.shuttle): Note that this applies to RL-10s in the Centaur G-prime (I don't know about earlier Centaur versions). 1) The oxygen-hydrogen mix is ignited by a "spark plug" kind of igniter. 2) The turbines on the RL-10 appear to be spun up from the tank head. This is in contrast to the liquid rocket engines on the Titan, which are spun up with the gas generated from solid-propellent "start cartridges." 3) The chamber pressure is 470 psia. The chamber temperature is 5,400 Rankine. The nominal vacuum Isp is 444 seconds. For (unfair) comparison, note that the chamber pressure of the SSMEs is around 3,000 psi, and the vacuum Isp is something like 460-470 seconds. Thought some other inquiring minds might like to know. --Glenn Serre serre@tramp.colorado.edu ------------------------------ Date: 28 Jun 90 04:05:50 GMT From: osu-20.ircc.ohio-state.edu!bunge@tut.cis.ohio-state.edu (Robert Bunge) Subject: Re: What Spherical Aberration is [Information about what Spherical Aberration is] Grey Hennessy says in his piece that it is HST's secondary mirror that is causing the problem. I just came from the news room where I work and in the Associated Press story, they seemed to suggest that they weren't sure which mirror was at fault. (I tried to download the story so I could post it here, but it didn't work). I've always wondered about the fancy system they developed to figure HST's primary so that it would maintain it's proper shape in orbit (Micro gravity). Does anybody know, in detail about this system? Could have it been the problem? What about the fancy "state- of-the-art fused mirror blank? Bob Bunge bunge@osu-20.ircc.ohio-state.edu P.S. Please, before complaining about the press for not explaining what spherical aberration is, sit back and look at what you had to do to explain it to a group of people who tend to know more about the subject then most people. I know exactly what spheical aberration is: I've made about a half dozen mirrors. ------------------------------ Date: 28 Jun 90 16:28:02 GMT From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: What Spherical Aberration is [First, a small complaint: would people please refrain from redirecting followups to sci.astro only? HST is of considerable interest to sci.space!] In article <12601306833012@osu-20.ircc.ohio-state.edu> BUNGE@osu-20.ircc.ohio-state.edu (Robert Bunge) writes: >... I've always wondered about the fancy >system they developed to figure HST's primary so that it would maintain it's >proper shape in orbit (Micro gravity). Does anybody know, in detail about >this system? Could have it been the problem? What about the fancy "state- >of-the-art fused mirror blank? I've seen one comment to the effect that the spherical aberration seems to be such a textbook-perfect case that it is almost certainly a design error rather than a manufacturing flaw. -- "Either NFS must be scrapped or NFS | Henry Spencer at U of Toronto Zoology must be changed." -John Osterhout | henry@zoo.toronto.edu utzoo!henry ------------------------------ Date: 28 Jun 90 19:19:30 GMT From: uoft02.utoledo.edu!fax0112@tut.cis.ohio-state.edu (Nash, David) Subject: Re: Unofficial HST report - aberration problem In article <1990Jun28.113016.901@uoft02.utoledo.edu>, fax0112@uoft02.utoledo.edu writes... > >Here is some more unofficial info and comments from developements >over the last few weeks. > >After a series of tests it has been realized that there is more >spherical aberation in the secondary than expected. Thus 90% >of the light is focused into an image about 2" in diameter, ^^^^^^^^^^^^^^ Is this right? I sure hope this is a typo, or else my news server is eating a decimal point somewhere (or that the rumor mills are grinding away, exaggerating all figures by the customary 50-100% ...). 2" is a *big* error for a mirror the size of Hubble's. For crying out loud, my little 4-inch scope will get down to around 2" on a good night... >poorer than earth based observations for most telescopes.... If that 2" figure is right, *All* scopes larger than those cheapo 60mm refractors in the toy section of Sears :-) >Robert Dempsey >Ritter Observatory > >(Thanks to MO and ANW for info and comments). --------------------------------------------------------------------------- David Nash (Yet another fugitive from behind the Zion Curtain.) (dnash@hmcvax.bitnet, dnash@hmcvax.claremont.edu) * .* * * * * * 'The best thing for being sad is to learn something.' - Merlyn, _The Once And Future King_ --------------------------------------------------------------------------- ------------------------------ Date: 28 Jun 90 23:13:38 GMT From: usc!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Galileo Update - 06/28/90 GALILEO MISSION STATUS REPORT June 28, 1990 As of noon Thursday (PDT), June 28, 1990, the Galileo spacecraft is 92,806,165 miles from the Earth and traveling at a heliocentric velocity of 54,113 miles per hour. The spacecraft is spinning at 3.15 rpm in cruise dual spin configuration. Round trip light time is 16 minutes, 38 seconds. Cruise Science Memory Readouts (MROs) were successfully performed for the Extreme Ultraviolet (EUV), Magnetometer (MAG) and the Dust Detector (DDS) instruments on June 25 and 28. The spacecraft tape recorder conditioning was performed on June 25 as planned. The fourteenth Retropropulsion Module (RPM) "flushing" activity was successfully performed on June 28. The Z, L and S thrusters only were flushed since the P thrusters are periodically used to perform SITURNS. Thruster flushing was performed at 40 bps. Detailed thruster temperature profiles are not available at this data rate. Successful flushing was inferred from other spacecraft telemetry measurement/events including Attitude and Articulation Control Subsystem (AACS) performance and thruster counts. The third of a three part Acquisition Sensor Calibration was performed on June 25 as planned. All required data was collected. The DDS memory change commanded last week went active on June 25, as commanded. DDS memory readout confirms that the memory changes required to capture low signal amplitude dust events was correctly loaded. The AC bus imbalance measurements this week were very stable and continue to indicate a near short circuit to chassis. The DC bus imbalance measurement showed more activity this week varying between 164 and 174 DN. The circuit measurement indicates 20.5 volts. The Venus-Earth-9 (VE-9) Cruise Plan was reviewed and approved by the project on June 27. This sequence covers the period from October 22 thru December 7 and includes windows for Trajectory Course Manuevers (TCM-7 and TCM-8). It also includes the Venus science data playback and the pre-Earth 1 Science Instrument turn-on and calibration. The Deep Space Network (DSN) reports that the load balancing work at the 70 meter tracking station (DSS-43) in Australia was completed and the 70 meter antenna returned to service one week early. DSS-43 provided its initial post balancing Galileo tracking support on June 26. ___ _____ ___ /_ /| /____/ \ /_ /| | | | | __ \ /| | | | Ron Baalke | baalke@mars.jpl.nasa.gov ___| | | | |__) |/ | | |___ Jet Propulsion Lab | baalke@jems.jpl.nasa.gov /___| | | | ___/ | |/__ /| M/S 301-355 | |_____|/ |_|/ |_____|/ Pasadena, CA 91109 | ------------------------------ Date: 29 Jun 90 00:24:27 GMT From: usc!cs.utexas.edu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!radio.astro.utoronto.ca!radio.astro!brian@ucsd.edu (Brian Glendenning) Subject: Re: HST focus problem >>>>> On 28 Jun 90 14:50:59 GMT, al@gtx.com (Alan Filipski) said: Alan> Couldn't this be corrected by digitally post-processing the image? Alan> By looking at stars you can evaluate the point spread function Alan> at each point of the field. The distortion of non-point objects Alan> could be modeled as a linear combination of these point spreads. Alan> As long as this function is invertible (which seems likely) Alan> you could reconstruct the image you want from the distorted image. This is a fairly standard technique in astronomy as well, the trouble is that you need a very good S/N to "improve" the resolution, and Astronomy is usually a low S/N business. If the psf is well known or can be determined accurately enough from stars in the frame I'd guess you might be able to somewhat restore the resolution in some high flux objects (if the real psf is "peaky with wings" you might conceivably be able to do quite well). Brian -- Brian Glendenning - Radio astronomy, University of Toronto brian@radio.astro.utoronto.ca utai!radio.astro!brian glendenn@utorphys.bitnet ------------------------------ Date: Wed, 27 Jun 90 11:52:09 CDT From: John Nordlie Subject: Re: Model rocket launchers Vincent Cate writes: > A related idea is called "piston launching". >You put the rocket in a tube so that the exhaust gas is contained and >pushes the rocket more. Fins need to spring out after leaving the >tube. You are sort of firing the rocket out of a cannon and this >gives you more velocity for a given amount of propellant. Have you forgotten about the spinning launch tube idea, Vincent? I also remember from some old NAR magazines seeing a piston launcher that fitted the rocket on top, erect fins and all. The piston was attached to a tube on which the rocket was mounted. The piston/tube assembly sits in the cylinder with only an inch or so of the tube protruding above the top of the cylinder. Upon firing, the piston/tube assembly would travel up the cylinder, until a mechanical stop would arrest it at the top. The rocket then detached and continued its flight. A pic of this device appears in a '70s issue of "Model Rocketeer". Sorry I can't be more specific, but I can't find the mag. ======================================================================= John Nordlie | I tried to think of something intellegent to say. | " Urgh..", I managed. | - Harry Harrison 'A Stainless Steel Rat | is Born' ======================================================================= ------------------------------ Date: 27 Jun 90 22:23:38 GMT From: sun-barr!newstop!texsun!digi!msissom@apple.com (Marc Sissom) Subject: Re: SpaceList Well, why not change the length of the second instead? Now the second lasts about as long as it takes light to travel some 300,000 km. We really ought to set this up so that light travels maybe 100,000 or 1,000,000. Perhaps we should stop using a base ten numbering system, and count in binary! All kinds of possibilities to make nature fit(or make our standards of measure fit). ------------------------------ Date: 28 Jun 90 23:18:05 GMT From: usc!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!aplvax.jhuapl.edu!jwm@ucsd.edu (Jim Meritt) Subject: Venus Anyone happen to know the temperature & presssure on Ishtar Terra (the "mesa" on Venus's north polar region that is about the size of the US and two miles high? For L. Niven fans: too small for Mt. Lookatthat, I fear... That that is is that that is. That that is not is that that is not. That that is is not that that is not. That that is not is not that that is. And that includes these opinions, which are solely mine! jwm@aplvax.jhuapl.edu - or - jwm@aplvax.uucp - or - meritt%aplvm.BITNET ------------------------------ End of SPACE Digest V11 #586 *******************