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 ; Tue, 19 Jun 1990 01:58:36 -0400 (EDT) Message-ID: Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Tue, 19 Jun 1990 01:58:07 -0400 (EDT) Subject: SPACE Digest V11 #540 SPACE Digest Volume 11 : Issue 540 Today's Topics: Re: Aim For The Moon - model rocket contest Re: Model rocket contest Re: Weather Satellite Photos Re: Weather Satellite Photos Hubble Space Telescope Update - 06/14/90 Re: 10 psi overpressure SpaceList 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: 18 Jun 90 18:41:42 GMT From: att!cbnewse!mckiou@ucbvax.Berkeley.EDU (kevin.w.mckiou) Subject: Re: Aim For The Moon - model rocket contest In article <9641@pt.cs.cmu.edu> vac@sam.cs.cmu.edu (Vincent Cate) writes: > >1992 marks the 500 year anniversary of Columbus' trip to America. It >would be fun to commemorate this with an "Aim for the moon" model rocket >contest. The goal of the contest could be to get a small transmitter near >the moon as cheaply as possible Geezzz...couldn't we start with orbiting the earth? Somebody want to volunteer to get the FAA clearance? :-) Kevin --------------------------------------------------------------------- Kevin McKiou UUCP: att!ihlpy!kwm NAR 51581 AT&T Bell Labs, Naperville, Ill Internet: kwm@ihlpy.att.com --------------------------------------------------------------------- ------------------------------ Date: Mon, 18 Jun 90 15:28:05 CDT From: John Nordlie Subject: Re: Model rocket contest >From: sam.cs.cmu.edu!vac@PT.CS.CMU.EDU (Vincent Cate) >Subject: Aim For The Moon - model rocket contest >1992 marks the 500 year anniversary of Columbus' trip to America. It >would be fun to commemorate this with an "Aim for the moon" model rocket >contest. The goal of the contest could be to get a small transmitter near >the moon as cheaply as possible (cost could be measured as total >newton-seconds of thrust for all stages). The only restrictions would be >that only off the shelf "model rocket motors" could be used and that the >standard transmitter must be in the payload. I think this limits people >to using "N" or smaller rockets. >It seems that using a small rocket to send a small transmitter to the >moon would be very possible. It would take a rocket with a number of >stages starting with the larger size motors; however, I think you could do >it without going so far as making a 10 stage rocket that starts with >multiple "N"s. This sounds like a very neat idea, if it can be done. However, I have some difficulty believing that a gun powder (model rocket engine propellant is basically gun powder, with some other burn-controlling chemicals added) rocket could achieve escape velocity, starting from the earth's surface. I remember reading in a book on rockets and jets that a gun powder powered rocket the size of a Saturn V cound not reach escape velocity. The chemical potential energy per unit weight is simply not high enough. I have never heard of an "N" model rocket engine ("A" - "F" yes, but not "N"), so I may be wrong about the fuel used in them. If these "N" engines were to use a suitably volatile solid fuel, it MIGHT be possible to get one into LEO, or better. >One might be the "cheapest" rockets to get within 100,000 >miles of the moon and go beyond the orbit of the moon. Another might be >for the rockets that come the closest to the center of the side of the >moon facing us (crash landings ok). Another might be for the shortest >trip time. Another might be for the cheapest to escape the Earth's >gravitational field. That's annother point: guidance. I was just out today flying a model rocket with a camera in the nose, and could not get the thing to fly the direction I wanted it to no matter what I tried. The rocket kept turning into the wind after takeoff (this makes perfect sense if you know a little about aerodynamics. ie: weather vane). I know of no simple guidence system that would keep a rocket on course (or even going straight up) while it travels through the atmosphere. A simple guidance system using gyros would probably be too heavy (or, if a very light one were made, too expensive). My final argument is this: There are many universities, organizations, and private individules out there who would love to do some space science. If it is possible to get very small payloads out of earth's gravity well using extremly cheap (compaired to comercial launch) off the shelf rocket parts, why hasn't anyone done it already? I know that "It's never been done, so it can't be done" is not a valid or logical argument, but don't you think someone would already be doing it now? (It's still a really neat idea, though!) ------------------------------------------------------------------------ John Nordlie : (Sorry, I couldn't come up with any clever : message/quote/disclaimer today) ------------------------------------------------------------------------ ------------------------------ Date: 18 Jun 90 17:35:45 GMT From: kr0u+@andrew.cmu.edu (Kevin William Ryan) Subject: Re: Weather Satellite Photos I have talked to the person responsible for the archive I use - they are upgrading their net link from 56Kb to 1.5Mb in the next week or two. When they have done so I will post the various GIF program directory listings and the address for anonymous FTP. These are GIF readers for all sorts of CPU's; IBM, Mac, X-windows, etc... In regards to bandwidth problems involved in opening FTP to all sorts of sat data, perhaps a poll should be taken to see what the most desired photos are. For me that would be daily Eastern US weather shots (preferably taken at the same time of day so I could view them as a series), and possibly the occassional IR shot for comparison. Would it be possible to offer some images via request for the less commonly desired shots, such as (for example) IR and ozone readings for the Southern Pacific? kwr P.S. Until I get the OK to publicize the archive I mentioned, please go ahead and hunt up your own sources for GIF and other image reading programs... ------------------------------ Date: 18 Jun 90 15:29:44 GMT From: kr0u+@andrew.cmu.edu (Kevin William Ryan) Subject: Re: Weather Satellite Photos One thing that probably should be done to reduce bandwidth is to compress the images. There are several possible ways to do this - I would suggest using the GIF (general image format) compression scheme, put together by the Compuserver folks, which is a slightly modified Lempel-Ziv compression algorithm. Depending on image complexity compression reduces image size by 10-90%, with an average of about 40%. Note that there are a variety of GIF format read/display programs available, freeware and otherwise, for almost any machine types. (I suggest looking at users groups, Compuserve sources, public archives, etc.) This is a reasonably widely used format. For sending via text-only channels (such as mail) the GIF or otherwise compressed image can be uuencoded into ascii. This expands the image size by about 30%, though, and the image usually will have to be broken into several pieces to be sent through most mail systems. I am extremely hesitant to list the one or two places I know of where the public domain GIf readers are stored - thus causing several thousand people to try to access them at once. I therefore am publicly requesting the people running such archives to list themselves if they are agreeable. In the meantime I can give several pointers - look for the Mac programs QuickGIF and Giffer, check the same archives that have NCSA Telnet, NIH Image, and other freeware, and read the alt.sex.pictures UseNet group, where they have been discussing GIF format images for a month or two; including Sun, X11, IBM, and Mac programs. kwr Internet: kr0u+@andrew.cmu.edu ------------------------------ Date: 17 Jun 90 19:06:09 GMT From: usc!jarthur!elroy.jpl.nasa.gov!jato!mars.jpl.nasa.gov!baalke@ucsd.edu (Ron Baalke) Subject: Hubble Space Telescope Update - 06/14/90 Hubble Space Telescope Update June 14, 1990 Bootstrap Phase B part 3, coarse wavefront measurements, finished on June 10. The data obtained from this test was felt adequate enough to provide an improvement in focus but not in alignment. Data from the independent measurements did not fully agree on where the focus was so a decision was made to go with the determination that had the best Signal-to-Noise Ratio (SNR). A command was issued to move the mirror 24 microns (less than 1 wave) or equivalent to ~0.5 arcsec change in the image. Planetary Camera (PC) pictures were then obtained. These new "after" images look different from the "before" image, but most of the difference is due to a small attitude change that was put in to move a bright star to the center of the image. Quantitative analysis of the image show no statistically significant difference between the two images. The likely explanation of this lack of difference was that the secondary was moved too much; it was moved through focus to a position roughly the same distance from focus, but on the other side of focus, as it was before the movement. The next phase of the focusing process, Bootstrap Phase B part 4, Exit Pupil Calibration, begins on June 12 and runs through June 15. The expectation is that after this test the mirror will be moved in focus and aligned. More PC pictures will be obtained on June 15. The Faint Object Spectrograph (FOS) is in the process of slowly turning their High Voltage (HV) on, all is going well so far. The High Speed Photometer (HSP) is running Detector Dark Count tests, Detector 4 tests have finished, Detector 1 testing is still in progress. So far, no anomalies have been reported. No new results from the analysis of the Pointing Control Subsystem (PCS) problems. Fixed Head Star Tracker (FHST) testing will be occurring a few times per week for a while. The Wide Field Planetary Camera (WFPC) is in full operate mode. There will be more pictures this week in support of Bootstrap Phase B focus and alignment. _ _____ _ | | | __ \ | | Ron Baalke | baalke@mars.jpl.nasa.gov | | | |__) | | | Jet Propulsion Lab | baalke@jems.jpl.nasa.gov ___| | | ___/ | |___ M/S 301-355 | |_____/ |_| |_____| Pasadena, CA 91109 | ------------------------------ Date: 18 Jun 90 18:38:03 GMT From: clyde.concordia.ca!news-server.csri.toronto.edu!utgpu!utzoo!henry@uunet.uu.net (Henry Spencer) Subject: Re: 10 psi overpressure In article <1990Jun15.211740.22967@portia.Stanford.EDU> gooch@portia.Stanford.EDU (Carl Gooch) writes: >...The force of the explosion was, I'm pretty sure, what >destroyed the Orbiter; it wasn't designed to take the stress of a >detonation wave hitting its bottom surface. Sorry, wrong; there was no explosion. The external tank fell apart, and the fuel burned, but there was no detonation and the orbiter was not particularly damaged by the fire. It was destroyed because the tank breakup threw it violently out of control in a Mach 3 slipstream, and its structure simply isn't strong enough to take that. It flies forward just fine, but flying sideways is out of the question even for jet fighters, and they are much tougher than shuttle orbiters. A closer reading of the Rogers Commission report will give you the details. -- As a user I'll take speed over| Henry Spencer at U of Toronto Zoology features any day. -A.Tanenbaum| uunet!attcan!utzoo!henry henry@zoo.toronto.edu ------------------------------ Date: Mon, 18 Jun 90 09:41:34 PDT From: greer%utdssa.dnet%utadnx@utspan.span.nasa.gov X-Vmsmail-To: UTADNX::UTSPAN::AMES::"space+@andrew.cmu.edu" Subject: SpaceList Space List: What every Space Enthusiast Should Know A List of Numbers and Equations Relevant to Space Exploration courtesy Dale M. Greer Update 4: 18-JUN-1990 Solar info from Liam E. Gumley Update 3: 23-MAY-1990 Rocketry info from Dave Newkirk Numbers 9.8 m/s^2 ( 10) -- Acceleration at surface of Earth (one g) 7726 m/s (8000) -- Earth orbital velocity at 300 km altitude 3075 m/s (3000) -- Earth orbital velocity at 35786 km (geosync) 6371 km (6400) -- Mean radius of Earth (Re) 6378 km (6400) -- Equatorial radius of Earth (Re) 1738 km (1700) -- Mean radius of Moon (Rm) 5.974e24 kg (6e24) -- Mass of Earth (Me) 7.348e22 kg (7e22) -- Mass of Moon (Mm) 1.989e30 kg (2e30) -- Mass of Sun (Ms) 3.986e14 m^3/s^2 (4e14) -- Gravitational constant times mass of Earth 4.903e12 m^3/s^2 (5e12) -- Gravitational constant times mass of Moon 1.327e20 m^3/s^2 (13e19) - Gravitational constant times mass of Sun 384401 km ( 4e5) -- Mean Earth-Moon distance 1.496e11 m (15e10) - Mean Earth-Sun distance (Astronomical Unit) 1371 W/m^2 (1400) -- Mean solar constant at 1 AU 6.672e-11 m^3/(kg*s^2) -- Universal gravitational constant 3.08 e13 km parsec 9.46 e12 km light year 0.46 km/s Speed of Earth's rotation at equator 3.0 e8 m/s Speed of light in a vacuum Conversions 1.61 km / mi 0.0254 m / in 3.28 ft / m 0.3048 m / ft 1.467 fps / mph (or 88 fps = 60 mph, exactly) 0.447 m/s / mph 2.2 lb / kg (2.2 pounds-mass, that is) Comparisons 1 MJ = 0.28 kW hr Equations Where d is distance, v is velocity, a is acceleration, t is time. For constant acceleration d = d0 + vt + .5at^2 v = v0 + at v^2 = 2ad General Gravity f = G m1 m2 / r^2 a = v^2 / r g = G Me / r^2 Escape velocity is the critical speed you need to achieve orbit: sqrt(g R) or sqrt(2 G M / R) For circular Keplerian orbits, where u is gravitational constant, a is semimajor axis of orbit, P is period. v^2 = u/a P = 2pi/(Sqrt(u/a^3)) Orbital eccentricity is: e = (apogee - perigee) / 2 r, where r is the average orbital radius. Rocketry The famous delta-v equation for how much velocity you get for burning a portion of fuel is: Dv = Ve LOGe(Mi / Mf), where Ve is the exhaust velocity, Mi is the initial mass, Mf is the final mass This can also be expressed by replacing Ve by g * Isp, where Isp is the specific impulse of the fuel. Here is a different form of the delta-v equation: Dv = Ve LOG(t0 / (t0 - t)), where t0 is the time when all the fuel will be exhausted, and t is the start time. This give the displacement of a constantly accelerating rocket: d = c^2 / a COSH(at/c - 1), where a is acceleration, t is the subjective time, c is speed of light With long time spans and/or high accelerations, this demonstrates special relativity in action. [ Note that COSH(x) = (e^x + e^-x)/2 ] The thrust of a rocket engine can be approximated by: 2 A (p - p0), where A is the minimum nozzle area, p is the chamber pressure, p0 is the pressure outside the engine Or by: Ve * F, where F is the rate of fuel use Miscellaneous f = ma -- Force is mass times acceleration w = fd -- Work (energy) is force times distance Atmospheric density varies as exp(-mgz/kT) where z is altitude, m is molecular weight in kg of air, g is acceleration of gravity, T is temperature, k is Bolztmann's constant. Up to 100 km, d = d0*exp(-z*1.42e-4) where d is density, d0 is density at 0km, is approximately true, so d@12km (13000 m -- 40000 ft) = d0*.18 d@9 km ( 9800 m -- 30000 ft) = d0*.27 d@6 km ( 6500 m -- 20000 ft) = d0*.43 d@3 km ( 3300 m -- 10000 ft) = d0*.65 Quantity Definition Units Energy Q Joules (J) Flux dQ/dt Watts (W) Irradiance dQ/(dt*dA) W per square meter (W/m^2) Monochromatic irradiance dQ/(dt*dA*dl) W/m^2 per micron (W/m^2/um^1) Radiance dQ/(dt*dA*dl*du) W/m^2/um^1 per steradian (W/m^2/um^1/sr^1) Flux at sun surface = 3.92e+26 Watts Selected Planetary Data Semimajor Axis Sidereal Synodic Incl.to Grav.Cst. Mass Period Period Eclipt. GM (10^12 (AU) (Mm) (Tr.Y.) (Days) (deg) m^3/s^2) 10^24kg Mercury 0.3871 57.9 0.24085 115.88 7.0042 22.03 0.33022 Venus 0.7233 108.2 0.61521 583.92 3.3944 324.86 4.8690 Earth 1.0000 149.6 1.00004 403.50 6.0477 Mars 1.5237 227.9 1.88089 779.94 1.8500 42.83 0.64191 Jupiter 5.2028 778.3 11.86223 398.88 1.3047 126712.0 1899.2 Saturn 9.5388 1427.0 29.4577 378.09 2.4894 37934.0 568.56 Uranus 19.1819 2869.6 84.0139 369.66 0.7730 5803.2 86.978 Neptune 30.0578 4496.6 164.793 367.49 1.7727 6871.3 102.99 Pluto 39.44 5900 247.7 366.73 17.17 1 0.012 The Moon 384.4 27.3217days 4.90 0.073483 (Suggestions? Favorite numbers, equations?) _____________ Dale M. Greer Center for Space Sciences, U.T. at Dallas, UTSPAN::UTADNX::UTDSSA::GREER ------------------------------ End of SPACE Digest V11 #540 *******************