Date: Wed, 2 Sep 92 05:00:05 From: Space Digest maintainer Reply-To: Space-request@isu.isunet.edu Subject: Space Digest V15 #154 To: Space Digest Readers Precedence: bulk Space Digest Wed, 2 Sep 92 Volume 15 : Issue 154 Today's Topics: 20 Questions About the Delta Clipper DCX?? Failed post from a long while ago: (2 msgs) Fireball over The Netherlands Wasn't (2 msgs) NASA speakers sought Single Stage to Orbit - How does it work? (2 msgs) TOPEX Update - 08/31/92 Upload Astronomy Lab for MS Win 3.x Venus orbiters (2 msgs) What is the speed of light measured from? (2 msgs) 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: Tue, 1 Sep 1992 14:40:07 GMT From: "Allen W. Sherzer" Subject: 20 Questions About the Delta Clipper Newsgroups: sci.space This was prepared as part of a packet of information on the SSRT project and the DCX and DCY vehicles. Permission is granted to reproduce and distribute any way you want. Allen -------------------------------- 20 question about the Delta Clipper 1> What is the Delta Clipper? A new spaceship that will take off straight up and land the same way, not gliding but under power, just like the rocketships in the 1950's science-fiction movies. Because of its improved engines, high-tech light-weight materials, and airline-like service procedures, the Delta Clipper could reduce the cost of getting to and from space by 90% or greater. Because it will be certified for flight like an aircraft, it will be able to operate from spaceports located in any state. 2> What will it look like? The production model Delta Clipper will be conical shaped, approximatley 130 feet high and 40 feet accross the base. It will have eight or more rocket engines, providing safe return engine out capability like any airliner. The Delta Clipper will not have wings like the Shuttle but will use small moveable flaps to help maneuver. It will not require strap-on external tanks or boosters. 3> When will it be flying? A 1/3 sized experimental vehicle, the DC-X, is on schedule for launch in April of 1993. The full sized orbital prototype, the DC-Y, could be ready to fly as early as the summer of 1997. 4> Where will it launch from? Test flights will be from White Sands Missile Range, New Mexico, but when the Delta Clipper goes into production any state in the Union will be able to have its own spaceport. Unlike the Shuttle, the Delta Clipper won't need a long runway, huge Vehicle Assembly Building, or Mission Control but only a 200 foot diameter concrete pad, a maintenance hangar, and a hydrogen/oxygen fuel facility. It will use existing global positioning satellites for navigation. 5> What will it cost to design and build the 1st Delta Clipper? The total cost of developing the first flight certified Delta Clipper will be comparable to or less than the development of a new commercial airliner. The cost of building an experimental prototype vehicle to demonstrate the concept and validate the operating and cost goals would be substantially less. 6> What will I have to pay to fly the Delta Clipper? The ticket price for early versions of the Delta Clipper, if it met current cost goals, could be less then the price for a round-the-world cruise on the QE2 ($40,000 to $140,000). A second generation vehicle could further reduce this cost. 7> How dangerous will it be? Once fully operational the Delta Clipper will be safe as flying on a typical commercial airliner. Delta Clipper will have engine out and all altitude abort capability. Plans are to have the Delta Clipper certified by the Department of Transportation, Office of Commercial Space flight. 8> What about air pollution, especially near the ozone layer? The Delta Clipper will burn only hydrogen and oxygen. Its exaust consists primarily of pure water vapor. 9> What about sonic booms and noise when launching or landing? When an airplane flies above the ground faster than sound, it generates a cone-shaped shock wave which we experience as a sonic boom. For this reason, the Concorde jet can't fly supersonically to inland airports in the US. Since the Delta Clipper launches straight up, the sonic boom is largely restricted to the spaceport area. When landing, the Delta Clipper will slow down to sub-sonic speed at about 70,000 feet altitude, thus minimizing the sonic boom to a barely audible level. 10> Who's building it? McDonnell Douglas, under a contract from the Strategic Defense Initiative Organization (SDIO), is building the DC-X for demonstration of the technological and operational feasibility of single stage rockets for supporting either suborbital flights. Based on successful testing of the DC-X, SDIO is interested in developing a fully reusable suborbital rocket to support their numberous suborbital test missions. The design, test results, and concepts will be available to other agencies to develop and demonstrate the orbital vehicle, the DC-Y. We hope to find another "home" for the DC-Y and Delta Clipper in DoD or NASA. 11> How much will the Delta Clipper be able to carry? Two crew members and 10 tons of cargo and/or passengers to Low Earth Orbit or 2 crew members and 5 tons of cargo/passengers to Polar Orbit. 12> Will it be able to fly to the Moon? A Delta clipper derivative vehicle, re-fueled in Low Earth Orbit, would be able to fly to the Moon, land there, and then return to Earth. The modifications required, however, would be substantial. 13> How often will the Delta Clipper be able to fly? The anticipated turn-around time for the Delta Clipper is a maximum of seven days. However, a one day turnaround may be feasible. 14> Why haven't we built a single-stage rocket before? The reason most rockets, including the Shuttle, have parts that drop off (stages) is this: every additional pound of vehicle that we lift all the way to orbit requires additional pounds of fuel. The additional fuel requires a little larger, and heavier, fuel tank, which then requires even more fuel to carry, and so on. There are three ways to deal with this problem: 1) make the rocket so huge (and expensive) that it can carry enough fuel to lift itself all the way to orbit, or 2) toss off empty tanks as you go (the traditional multi-stage method), or 3) make your engines and vehicle structure so efficient and light weight that you don't need to carry huge amounts of fuel or throw away pieces of your ship. This last is the principle behind the Delta Clipper. It is only recently, under such programs as NASP, and aircraft developments that we have sufficently developed and demonstrated light weight materials that will allow the Delta Clipper to work. 15> What if something goes wrong during a flight? Commercial airplanes don't need all their engines to fly safely. The same principle will be used with the Delta Clipper. If there is an engine malfunction during the assent, the Delta Clipper will be capable of either continuing on to orbit orreturning to the spaceport. If the Delta Clipper needs to return from orbit sooner than expected, it will be able to maneuver over 1200 miles to either side. Unlike the Shuttle, which requires a three mile long landing strip, the Delta Clipper will be able to land on nbalmost any reasonably flat spot. 16> Why should I believe all these claims for the Delta Clipper when similar ones were made for the Shuttle twenty years ago? The Shuttle's design was "frozen" in the 1970's. Using the technology available then would have resulted in a SSTO that was extremely large and expensive. A Delta Clipper sized SSTO based on 1970's technology would not have ben able to reach orbit. In the 20 years since then, we have learned a lot about design, light-weight materials, trajectory optimization, avionics, computers, and engine design. In addition, the Delta Clipper is being designed with supportability and operability as priority considerations. For example, the engines on the Delta Clipper won't run at 110% of their design capacity, as the Shuttle's do, so they won't have to be torn down and repaired before each flight. If on-board diagnostic instruments indicate a problem with a Delta Clipper engine or any other component, it is designed so components (called line replaceable units) can be pulled and replaced quickly after landing. 17> Why isn't NASA building the Delta Clipper? The task of proving the technology availability for a single stage rocket vehicle was assigned to SDIO. SDIO with its streamlined management style is an excellent agency for developing and demonstrating new technology initiatives. Once the technology demonstration is completed, the concept will be available for either Department of Defense or NASA to develop an orbital capable Delta Clipper. 18> Why isn't industry building the Delta Clipper? McDonnell Douglas and its teammates have already made a significant investment in the basic technologies and the skills and facilities necessary to develop a SSTO. The government needs to take the next step of funding an experimental prototype vehicle to prove the Delta Clipper's basic concepts and technologies. Once demonstrated, the commercial sector may be interested in investing in an operational system. Such a system could have an enormous impact on the development of space as an commercial market as well as the future of the US space program. 19> What factors could cause the Delta Clipper program to founder? Money: Though the Delta Clipper program is cheaper than many Federal programs, it still is in danger from a budget-conscious Congress who may not be aware of the benefits of the Delta Clipper or who feel the program has no real constituency. We hope to change their minds about this. 20> What can I do to help? Get on our mailing list, be willing to write letters to Congres when asked, learn about the Delta Clipper, ask all your friends to support it too. -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "If they can put a man on the Moon, why can't they | | aws@iti.org | put a man on the Moon?" | +----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Tue, 1 Sep 1992 14:37:18 GMT From: "Allen W. Sherzer" Subject: DCX?? Newsgroups: sci.space In article <78740@ut-emx.uucp> wolfone@ccwf.cc.utexas.edu (Patrick Chester) writes: >Pardon me for seeming clueless, but what is the dcx? DCX is a 1/3 scale prototype of a Single Stage to Orbit vehicle. It will be used for suborbital testing next summer. If all goes well another agency will pick up development and develop a full scale vehicle which can achieve orbit. If it works, it will reduce the cost to orbit by one to two orders of magnitude. We have a document called '20 questions on SSTO which I will post in a bit. It should answer most of your questions. If you want to help make this happen, contact me. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "If they can put a man on the Moon, why can't they | | aws@iti.org | put a man on the Moon?" | +----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: Tue, 1 Sep 92 13:01:49 -0500 From: pgf@srl03.cacs.usl.edu (Phil G. Fraering) Subject: Failed post from a long while ago: This is a follow-up that never made it... It just about sums up my feelings about manned space shots as entertainment... Date: Sun, 2 Aug 92 21:54:11 -0500 From: pgf (Phil G. Fraering) stgprao@xing.unocal.com (Richard Ottolini) writes: >I don't know if anyone else feels the same way, >but I find the space shuttle missions this summer to be more >interesting than the Olymnpics and presidential conventions. >I still get a thrill when I see a manned spacecraft and takeoff >even though I've been watching them for 30 years. You might as well feel thrilled. It cost enough money. If you don't at least feel thrilled, you're left with the scientific justification for the mission, which according to some groups is dubious... ------------------------------ Date: Tue, 1 Sep 92 13:04:33 -0500 From: pgf@srl03.cacs.usl.edu (Phil G. Fraering) Subject: Failed post from a long while ago: This is a follow-up that never made it... It just about sums up my feelings about manned space shots as entertainment... Date: Sun, 2 Aug 92 21:54:11 -0500 From: pgf (Phil G. Fraering) stgprao@xing.unocal.com (Richard Ottolini) writes: >I don't know if anyone else feels the same way, >but I find the space shuttle missions this summer to be more >interesting than the Olymnpics and presidential conventions. >I still get a thrill when I see a manned spacecraft and takeoff >even though I've been watching them for 30 years. You might as well feel thrilled. It cost enough money. If you don't at least feel thrilled, you're left with the scientific justification for the mission, which according to some groups is dubious... ------------------------------ Date: Tue, 01 Sep 92 14:39:21 EST From: PHARABOD@FRCPN11.IN2P3.FR Subject: Fireball over The Netherlands Wasn't Regarding the August 19, 1992, event over The Netherlands, Harm Munk writes (Mon, 31 Aug 1992 07:42:08 GMT): >So, what was it? Rumours in the newspapers suggested that it was that >highly secretive airplane that Lockeed is developing for the DoD: the >two stage get to orbit plane (like DynaSoar and Saenger ?). Now, >this plane has been sighted in the US a few times. Here is an article from Aviation Week & Space Technology, August 24, 1992, about this "highly secretive airplane": RECENT SIGHTINGS OF XB-70-LIKE AIRCRAFT REINFORCE 1990 REPORTS FROM EDWARDS AREA William B. Scott/Lancaster,Calif. A large aircraft having a planform reminiscent of the Air Force/North American XB-70 supersonic bomber of the 1960s has been seen flying on the U.S. East and West coasts over the last two years. Two recent detailed reports of large, light-colored, XB-70 like aircraft - one in Georgia and the other in California's Mojave desert - provided new data that reinforce past sightings near Edwards AFB, Calif. Since September, 1990, residents of Mojave, Calif., and workers at Edwards AFB have seen a large, delta-shaped, light-colored aircraft flying in the area. A total of five separate sightings of this vehicle has been reported to AVIATION WEEK & SPACE TECHNOLOGY. Observers said they first saw a large, primarily delta-shaped aircraft at night during the summer of 1990. On Sept. 13, 1990, and Oct. 3, 1990, the same type of aircraft was seen flying near Mojave, Calif., in the late evening. Mojave is about 16 naut. mi. northwest of Edwards AFB. The dusk sightings yielded descriptions and sketches of the aircraft planform, nose and main landing gear door locations, leading edge tile-like patterns, and lightings layout. Observers consistently reported a red light beneath the nose, amber lights near the delta's wingtips, and a white light between the main gear doors. Engine noise associated with the aircraft seen on Sept. 19 was described as a low-pitched rumble. However, noise from two chase aircraft - one was an F-16, the other was not identified - may have combined with that of the large aircraft, distorting the latter's sound. Afterburner flames from twin exhaust ports located under the wing trailing edge and immediately outboard of the aircraft centerline during the Oct. 3 sighting. CLUES ABOUT POSSIBLE MISSION A similar aircraft was seen in April, 1991, at about 11 a.m., flying north of Edwards AFB at an estimated altitude of 5,000-10,000 ft. An observer said it was large - dwarfing an F-16 chasing it - and was light colored, possibly white. Independent sightings this year produced detailed sketches that correlate well with earlier ones and provide additional clues about the aircraft's possible mission. The first sighting this year was near Atlanta, Ga., on May 10. Glenn Emery, now a writer associated with Cable News Network, said a large, unidentified aircraft was flying eastbound at about 5 p.m. Because its size was unknown, its altitude was difficult to judge, but was estimated to be 10,000- 15,000 ft. The vehicle was clearly higher and faster than the airline traffic descending for landing at Hartsfield Atlanta International Airport. It was not leaving a contrail. He described the aircraft's planform as large, somewhat like an XB-70, but with a large forward wing or canard. Its dual engines were "extremely noisy", producing a deep-pitched, perioding beating sound, he said. Suggestions that he had seen the British Aerospace Concord or a Beech Starship were discounted by Emery, who said the shape, size and sound were inconsistent with either of those aircraft. Another sighting, on July 12 at 11:45 p.m., occurred near a Lockheed-operated radar cross section (RCS) test range in the Mojave desert. Described as an "XB-70-like" shape, the aircraft tuned its landing lights on while at fairly high altitude, then descended quickly, following an S-pattern flight track. It made a final turn at about 200 ft. above a road, crossing less than a mile in front of a motorist who had watched its descend. Ambient noise masked any sounds from the aircraft. Bright moonlight illuminated the aircraft's upper surfaces, giving the observer a good look at the planform during the turn. The aircraft rolled out, presenting a side view as it descended and landed at a private Helendale airport adjacent to the Lockheed RCS test facility. Located about 15 naut. mi. southwest of Barstow, Calif., Helendale Airfield's three runways are close to civil pilots on current aero- nautical charts. However, Lockheed aircraft still land there when shuttling personel between its Burbank site and the RCS facility. Although weather was clear and calm at the Helendale field that night, several thunderstorms were reported in the Las Vegas area and through the highly classified range complexes in central Nevada. Based on observer reports, this unidentified aircraft's features include: # Large size, estimated to be close to 200 ft. in length. Observers near Edwards AFB said the vehicle "dwarfed" F-16 chase aircraft. # A large aft section with a clipped-delta platform. A narrower, blended fuselage extends from the delta's vertex forward to a clear- canopied cockpit and sharp nose. The main delta section has a prominent, raised spine along the top centerline. Upward-canted vertical fins rise at each outboard tip of the delta planform. # A prominent dark line extending longitudinally along part of the aft raised section. At the aft end of the line, just ahead of the trailing edge and between the engine nozzles, a broken visual pattern was seen, but observers could not describe it. # A forward wing or canard of fairly long spane. The canard, possibly used only for takeoff, landing and slow-speed regimes, may pivot or sweep aft for internal stowage during high-speed flight (Some observers reported a dominant canard, while others did not recall, suggesting it can be stowed). # Dual rectangular engine exhaust nozzles at the aircraft's trailing edge. # Light-colored top and bottom surfaces, with dark leading and trailing edges. Although the propulsion system is unknown, observers have reported a "very loud, low-pitched roar" with a rhytmic beat to it. They did not hear a series of detonations, which have been associated with high-speed "pulser" vehicles that create "donuts-on-a-rope" contrails (AW&ST May 11, p. 62) (end of article) With this article, there is an "artist's composite" of the craft. It is said in the caption that "The aircraft configuration suggests a variety of mission roles, including carriage and high-speed launch of an unmanned vehicle into orbit". At least this last point should interest sci.space subscribers ! In the same issue of AW&ST, there are two other related articles: UNITED 747 CREW REPORTS NEAR-COLLISION WITH MYSTERIOUS SUPERSONIC AIRCRAFT, by Michael A. Dornheim/Los Angeles. SECRET AIRCRAFT ENCOMPASSES QUALITIES OF HIGH-SPEED LAUNCHER FOR SPACECRAFT, by William B. Scott/Lancaster, Calif. (sci.space subscribers should be interested in this one !) ._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._. Now a few comments. 1) It is not the first time that "large, primarily delta-shaped aircrafts" are reported near Edwards AFB. Since the end of 1989, a "big wing" has been seen several times over Antelope Valley. See AMERICA'S NEW SECRET AIRCRAFT, Popular Mechanics, December 1991 (I posted this article twice on sci.space, but it seems that practically nobody was interested). However, this "big wing" was said to be silent, and could hover in any position (hence the airship hypothesis). It seems that the XB-70-like object goes fast, and is generally noisy. 2) A contributor to the "Skeptical Inquirer" assured me that all secret aircraft tests are over the deserts of California and Nevada. What was this aircraft doing over Atlanta, Georgia, on May 10, (1992 ?). 3) "Large, primarily delta shaped aircrafts" appeared over Belgium in November 1989, and have been seen thousands times during about two years. Though U.S. citizens are highly civilized (?), I am not sure that five U.S. witnesses = some ten thousands Belgian witnesses. 4) Though most of time only delta shapes have been seen in Belgium, there were a number of reports of "narrower fuselage" and/or "forward wing", especially in year 1991. A drawing made by a witness looks like the AW&ST "artist's composite". Some Belgian inquirers suggest the possibility of composite structures (Lego type). 5) "Large size, estimated to be close to 200 ft. in length." This fits well the size of the Belgian object: a triangulation made from one of its hovering stations gave: isocele triangle, 50 meters basis, 55 meters height. 6) Though the Belgian object was generally silent, in some occasions very loud roars were reported. 7) It seems that F-16s like very much chasing these objects. In Belgium there has been an unsuccessful chase during the night March 30-31, 1990 (see the Belgian Air Force report I posted on sci.space on February 28, 1992). By the way, the Belgian Center of Electronic Warfare is still studying the video record of the interception. I know a bit more about that, but since my info comes from private mails, and since nobody on sci.space seems interested in that, I will keep it for myself. 8) As said Harm Munk in his posting, >And why would the DoD start testing a secret plane outside US territory? J. Pharabod ------------------------------ Date: Tue, 1 Sep 92 13:40:56 GMT From: Dean Adams Subject: Fireball over The Netherlands Wasn't Newsgroups: sci.space,sci.astro cecil@physics.unc.edu (Gerald Cecil) writes: >According to Aviation Week & Space Technology (aka AvLeak) in >issues prior to Aug. 24, Uh, there was a considerable amount of NEW information in the August 24th issue. WHY would you want to limit your reply only to the old info? >this aircraft is an SR 71 replacement developed by Lockheed Skunkworks. >Speeds estimated at 3500+ mph. *Not* a 2 stage to orbit plane. NO. The 8/24 AW&ST *specifically* talked about a vehicle which potentialy DOES have a 2-stage to orbit mission capability. > described as `bat-like'' similar to the B2 airfoil. Now it sounds like you are talking about the *subsonic* TR-3A, which is something totally different from the Aurora(s). >Daytime photos of peculiar corkscrew contrails that have been attributed Now you're back to the older Aurora/pulser concept. I tend to think this is a *different* (and smaller) vehicle from the large "Concorde-like" aircraft reported in Europe, and also described in the recent AW&ST. >presumably because the DoD has now sunk so much money in to it and >distributed its contractors into so many Congressional districts The Lockheed Burbank Skunk-Works is likely the main contractor. With such an ultra-black project I doubt it was spread around that much. >Yet another multi-billion dollar aerospace program to >protect US airspace from the Bosnian airforce. NO, it is to "protect" us from being ignorant about the world around us. Intelligence gathering is something that will always have considerable value, with or without any "evil empire" to be worried about. -{ DA }- ------------------------------ Date: 1 Sep 92 16:16:25 GMT From: David M Chelberg Subject: NASA speakers sought Newsgroups: sci.space I am interested in finding out if NASA has any program to allow their researchers to give talks at Universities. What policies does NASA follow with regards to invited lectures from their scientists? Does NASA have some kind of distinguished speaker program? I would think that they do, as it would be great publicity, and work well with their educational goals. If anyone has information on how to arrange NASA speakers, please email me. In particular, I am interested in speakers with a CS emphasis. Thanks, -- Prof. David Chelberg (dmc@ecn.purdue.edu) __ _ _ _ __ _ / ) / ' ) ) ) / ) / // / / / __. , __o __/ / / / / /_ _ // /___/> __ _, /__/_(_/|_\/ <__(_/_ / ' ( o (__/ / /_ Subject: Single Stage to Orbit - How does it work? Newsgroups: sci.space In article tjn32113@uxa.cso.uiuc.edu (Tom Nugent ) writes: >From what I understand, 5 years ago you could not get into space without >stages. Depends. With expendables it looks like getting to LEO with a single stage has been possible technically for some time. Reusable SSTO's are likely just now possible. The Aerospace Corporation study (done before SSRT Phase I) used Max Hunters design. They concluded that the vehicle could now just barely be built with a payload of between 20,000 and -600 pounds (the latter means it is 600 pounds too heavy to lift off). They said engine improvments of a few seconds of impulse and materials only a few % lighter make it possible. SSTO is a game of inches. Allen -- +---------------------------------------------------------------------------+ | Allen W. Sherzer | "If they can put a man on the Moon, why can't they | | aws@iti.org | put a man on the Moon?" | +----------------------234 DAYS TO FIRST FLIGHT OF DCX----------------------+ ------------------------------ Date: 1 Sep 92 15:29:43 GMT From: "KEVIN D. DAWSON" Subject: Single Stage to Orbit - How does it work? Newsgroups: sci.space In article henry@zoo.toronto.edu (Henry Spencer) writes: >From: henry@zoo.toronto.edu (Henry Spencer) >Subject: Re: Single Stage to Orbit - How does it work? >Date: Fri, 28 Aug 1992 16:53:29 GMT >As currently planned, SSTO will use very ordinary engine technology, >except that it will probably use either a "plug nozzle" (which puts the >entire base area of the rocket to work as the nozzle) or telescoping >nozzles that can be made longer in flight. Both of these basically just >optimizes the nozzle design to match changing outside pressure; neither >has flown, although both look workable. Last I heard, the feeling was >that telescoping nozzles looked less risky. I Take it the Telescoping nozzle on the Peacekeepers upper stage doesn't count because it only telescopes for storage? -Kevin- ------------------------------ Date: Tue, 1 Sep 1992 22:56:19 GMT From: Ron Baalke Subject: TOPEX Update - 08/31/92 Newsgroups: sci.space,sci.astro Forwarded from: PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. (818) 354-5011 TOPEX/POSEIDON STATUS REPORT August 31, 1992 The TOPEX/Poseidon satellite has fully recovered from the safe hold that it experienced last Thursday. Today the satellite is performing nominally and is healthy. Attitude control, solar array, batteries, telecommunications, and the on- board computer are all functioning normally. Today, the NASA altimeter is in the track mode and obtaining good data. Since launch, the navigation team and the precision orbit determination team have been observing a slight decay in orbit. It is currently about 10 cm a day, which is down from 30 cm a day last week. The 10 cm/day appears to be expected drag on the satellite. The higher decays observed previously were probably due to outgassing. The next major satellite event is the In-Plane Maneuver One is planned for Wednesday, Sept. 2, 1992. ###### ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Anything is impossible if /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | you don't attempt it. |_____|/ |_|/ |_____|/ | ------------------------------ Date: Tue, 1 Sep 92 16:24:13 GMT From: David Fuzzy Wells Subject: Upload Astronomy Lab for MS Win 3.x Newsgroups: comp.windows.ms.programmer,comp.windows.ms.misc,comp.ibm.pc.misc,comp.os.ms-windows.apps,sci.space,sci.astro,sci.edu This file is available at ftp.cica.indiana.edu in the windows area. Fuzzy ------------------------------ Date: Tue, 1 Sep 1992 14:10:12 GMT From: David Knapp Subject: Venus orbiters Newsgroups: sci.space In article <9209010437.AA10756@cmr.ncsl.nist.gov> roberts@CMR.NCSL.NIST.GOV (John Roberts) writes: > > >Will the trajectory of Pioneer Venus as it burns up provide useful >information for the planning of the Magellan aerobraking experiment? >(Density and drag at various altitudes, etc.) The density and drag at various altitudes is strongly correlated to solar activity. This is one factor which will help determine the time of demise of the PVO itself. Since we cannot know exactly what the solar activity will be in the future, planning for aerobraking is somewhat like weather forecasting. -- David Knapp University of Colorado, Boulder Highly Opinionated, Aging and knapp@spot.colorado.edu Perpetual Student of Chemistry and Physics. Write me for an argument on your favorite subject. ------------------------------ Date: Tue, 1 Sep 1992 23:10:48 GMT From: Ron Baalke Subject: Venus orbiters Newsgroups: sci.space In article <9209010437.AA10756@cmr.ncsl.nist.gov>, roberts@CMR.NCSL.NIST.GOV (John Roberts) writes... >Will the trajectory of Pioneer Venus as it burns up provide useful >information for the planning of the Magellan aerobraking experiment? >(Density and drag at various altitudes, etc.) That is the plan. The Magellan and Pioneer projects are working together to collect the data from Pioneer Venus to be applied toward Magellan's aerobraking next year for Cycle 5. Of course, this is assuming that Magellan isn't turned off at the end of Cycle 4. Magellan is in Cycle 3 right now with Cycle 4 due to start on September 14. Each cycle lasts 243 days, or one Venusian day. ___ _____ ___ /_ /| /____/ \ /_ /| Ron Baalke | baalke@kelvin.jpl.nasa.gov | | | | __ \ /| | | | Jet Propulsion Lab | ___| | | | |__) |/ | | |__ M/S 525-3684 Telos | Anything is impossible if /___| | | | ___/ | |/__ /| Pasadena, CA 91109 | you don't attempt it. |_____|/ |_|/ |_____|/ | ------------------------------ Date: Tue, 1 Sep 1992 11:18:00 GMT From: pete Subject: What is the speed of light measured from? Newsgroups: sci.space In article <1992Aug31.173411.13396@cbfsb.cb.att.com>, wa2ise@cbnewsb.cb.att.com (robert.f.casey) writes... >Makes you wonder how the "particle" of light "knows" how fast or slow to >speed up by to be travelling at the -speed o' light- at or near the >local frame of reference. Does it "feel" the local gravity, or something? > What you have to understand is that c is not just a velocity. The way this universe is constructed, it's like a point that time and space both pivot on. You could say that c is infinitely fast, for anything travelling at it, it's just that the geometry - in fact the _logic_ - of the universe requires that it not be seen as infinitely fast by other observers. For instance, if you board some wonderful rocket, which can sustain constant acceleration ( in your frame of reference ) and commence accelerating, it will seem to you that you just keep getting faster and faster, and you pass c without incident. The only catch is that in the rest of the universe you travel through, time seems to be going by faster and faster relative to yourself, such that to observers in other frames, your velocity never quite reaches c. They also see your time slowing down, so they can understand why you might think yourself going faster than c ( for simplicity I've left out all the interesting details of how times can be compared between reference frames). Now for light, and anything else travelling at c, duration of time has slowed to 0 as seen from any other reference frame, so this can be seen as equivalent to travelling infinitely fast. This sort of solves the problem that led Einstein to relativity in the first place - how, if one were in the frame of reference travelling with light, and observed the (now stationary) electromagnetic fields which comprise it, one would see the EM fields vary in amplitude periodically in space, which according to Maxwell's equations shouldn't be possible without electric charges at the local maxima. The solution is that in relativity, this frame of reference is not well defined, and it occupies no time, so it's never really there to contradict Maxwell. Thus light always knows how fast to go: as fast as possible. The moral of the story is that the world is not at all as it seems, and nothing like our naive Aristotelian/Newtonian intuitions. ======================================================================== Wait until time is fully dilated Pete Vincent before releasing tangent bundle... ------------------------------ Date: Tue, 1 Sep 92 18:19:25 BST From: amon@elegabalus.cs.qub.ac.uk Subject: What is the speed of light measured from? >> Where is the speed of light measured relative to? > The speed of light does not add and subtract to other velocities, > like relative velocities of anything else. Well, correct in intent, but not quite true mathematically. The plus and minus operators are not the linear 2+2=4 operation you learn as a small child, although with small velocities in a given frame of reference they approximate it. Adding two large velocities results in a smaller than expected result because of the relativistic effects. The "addition" works such that the resultant velocity never exceeds c. Moving from one frame to another utilizes mathematical rules which preserve this constancy by modifying space and time metrics. (This is one way to look at it.) The atomic clocks and meter sticks of observers in different reference frames have different seconds and meters. They differ in such a way as to insure the constancy. It's just the way space-time is built. Look up the Lorentz factor in any physics book. There also may be info on this in the FAQ. Not certain of that, but it has come up many, many times before. ------------------------------ End of Space Digest Volume 15 : Issue 154 ------------------------------