Suzy B Software 2

home *** CD-ROM | disk | FTP | other *** search

/ Suzy B Software 2 / Suzy B Software CD-ROM 2 (1994).iso / nasa / 25voyage / 25voyage.asc next >

Wrap

Text File | 1995-05-02 | 39KB | 872 lines

12108 11-AUG 22:04 Space & Technology Neptune flyby From: JOELDAVIS To: ALL I'll be down at the Jet Propulsion Laboratory the week of August 21 for the Voyager 2 flyby of Neptune. The closest approach is sometime in the evening of Thursday August 24 (that's Earth time, relatively speaking, which we must do since the round-trip light-time from Voyager 2 is something like six hours now). Anyway. I'm doing some live reportage for a couple of radio stations up here in Washington State, and also writing daily feature articles for my old home town newspaper in Ventura, California. I will also try to post daily (or nightly) updates to youse folks here on the SF SIG of Delphi. Okeydokey? ==Joel -*- 12212 19-AUG 00:02 Space & Technology Voyager 2 Report From: JOELDAVIS To: ALL Good day, all. Here's a prefatory report on the Voyager 2 flyby of Neptune, from yr umble Delphi reporter, Joel Davis. In fact, this is quite prefatory. I've not yet settled in at the Jet Propulsion Laboratory. However, it looks like there will be plenty to tell you about. I will head over to JPL for the first time this trip on Sunday, August 20. So I should have some things for you that evening. The delightful and fearsomely competent Mary Beth Murrill of JPL's Public Information Office has scheduled at least two interviews for me (and you!) beginning at 10 am (all times are Pacific Daylight, unless otherwise noted). I'll be talking that day with George Textor, the deputy project director; and with Jim Warwick, the Principal Investigator (read "Head Scientist") for the Planetary Radio Astronomy instrument aboard Voyager 2. Textor is one of the veterans of Project Voyager. He has been with the project at least since the Saturn flyby of 1981, and was deputy project manager for the 1986 Uranus flyby. George will give us an overview of the mission's status as of that morning. I'll have him update me on the latest discoveries at Neptune by Voyager 2, including the discovery of the four new moons and the confirmation of ring arcs around the planet. Textor may also have something to tell us about a discovery made just today (August 18), a discovery about which Jim Warwick will give more detail. Warwick and his team have found evidence for a magnetic field around Neptune. As I noted, this was just confirmed earlier today, according to Mary Beth. I don't know how much of this will show up on the AP wire or in your daily newspaper. However, in my interview with Warwick I will press for details. In particular, I am interested to know how Neptune's magfield compares with Uranus's and Earth's. Some of you may recall that Uranus has an utterly bizarre magnetic field--its magnetic poles are tilted at an angle of 60 degrees to that of the planet's spin axis! And Uranus's spin axis is itself tilted at about 98 degrees to the ecliptic. I.e., Uranus seems to "roll" around the sun. The result is that Uranus's magnetic field traces a weird corkscrew path in space, making for who knows what kinds of interesting effects. Questions: What's the orientation of Neptune's magnetic field? It's strength? Any trapped radiation belts there, a la Earth's Van Allen belts? These and more for the entertaining Jim Warwick (whose at-work attire runs to powder blue sweat pants and rumpled fishing hats). That's it for now. More, I hope, on the evening of August 20! ==Joel Davis .. -*- 12251 20-AUG 23:27 Space & Technology Voyager 2 Report From: JOELDAVIS To: ALL George Textor, a burly bear of a man with a deceptively soft voice, is the Mission Director for the Voyager 2 flyby of Neptune later this week. He held the same position for the spacecraft's encounter with Uranus in 1986. He thus has considerable experience with Voyager. He also sees the project with a good deal of perspective. And from his perspective, the Neptune encounter is proceeding with astonishing smoothness. One reason for the smoothness has to do with advance planning. For example, much of the work writing new programs for Voyager's onboard computers was carried out nearly three years ago, explains Textor. "We laid out a schedule for ourselves that gave us a lot of time to make updates to those computer programs, and also to write new ones if necessary," he says. Some of that software designing involved very intensive work. For example, the sunlight levels at Neptune are much lower than they were at Uranus. The light is so dim, in fact, that the images taken by Voyager's two onboard cameras will have to be time exposures several minutes long. The original programs in Voyager's computers were not able to make the cameras do this. So the programs had to be completely rewritten to carry it out. Because the time exposures are so long, the spacecraft must be moved in order to pan the camera during the imaging. That, in turn, meant rewriting computer programs that tell Voyager 2 when and how to move itself in space. Textor points out that all these changes and and other work behind the scenes is being done by a Project Voyager team that includes many new faces. However, he does not consider that a problem, but an asset. "It's fun to work with new people. With new people on the team, you get new ideas, and we learn new ways to doing old things. That's important," he says. "We knew that the computer programs running Voyager 2 during the actual flyby were going to be very complex. And we also knew that we would have to be able to make changes in those programs right up to the last minute," says Textor. "So two years ago, we set up a special group of people whose job it was to look at everything we would have to do during the flyby that way really critical," he explains. The special planning group used their findings to help put together the Voyager Project's test and training program, which took place in February. The training period inlcuded dry runs of all the critical parts of the actual Neptune flyby. Many problems had taken place during the test and training for the Uranus encounter in 1986, so Textor was concerned that this testing period go well. It turned out, in his own words, to be "the smoothest test and training session I have ever seen. In fact, I was beginning to be concerned that we were 'peaking' too soon! "But it looks like all of our people are doing very well," he says. So is the aging but still plucky spacecraft. "Voyager 2 looks great," declares Textor. "We have plenty of maneuvering fuel onboard, enough to last for another 25 years, in fact. We were able to cancel one of our last mid-course maneuvers, and that saved us even more fuel," he adds. Spacecraft engineers continue to watch the power levels on Voyager 2. But Textor says that there is nothing to worry about. The spacecraft's special nuclear batteries are still producing more than enough power to run all of Voyager 2's computers and scientific instruments. The spacecraft should have enough power to run itself, in fact, through the first years of the next century. As for Textor himself, he is not sure what he will do after Voyager 2 completes its Neptune flyby and begins the "Voyager Interstellar Mission" in October. He does plan to stay on through the beginning of that next phase of Voyager's life. "But if it seems to start getting boring, I will begin looking for something else to do," he laughs. For right now, though, George Textor is focused on Neptune. ==Joel Davis Copyright (c) 1989 by Joel Davis ----------------------------------------------------------- Today's Gee-Whiz Facts: The total cost of the Voyager Mission, from May 1972 (when the Project formally began) through the Neptune encounter, is $865 million. This is about 20 cents per U.S. resident per year, or half the cost of one candy bar per person per year since the project began. The entire cost of Project Voyager is less than the daily interest on the U.S. national debt. Five trillion bits of scientific data will have been returned to Earth by both Voyager spacecraft at the end of the Neptune flyby. This is the equivalent of 6,000 complete sets of the Encyclopedia Britannica, or 1,000 bits of data for each person on Earth. . -*- 12261 21-AUG 23:27 Space & Technology RE: Voyager 2 Report (Re: Msg 12260) From: JOELDAVIS To: RKRUEGER The IRIS had some strange glitches crop up during the Uranus flyby, but they just as mysteriously went away before the encounter with the planet in 1986. IRIS, the infrared instrument, was designed to measure temperatures in the planetary atmosphere, and also of the surfaces of the moons. Sadly, I cannot tell you exactly what Rudy Hanel and his folks found. I did not follow that instrument closely while writing "Flyby." However, you might want to check the issue of "Science" magazine, I think early June 1986, which included the first major reports of science results from that flyby. ==Joel -*- 12262 21-AUG 23:34 Space & Technology Voyager 2 Report From: JOELDAVIS To: ALL Hello, all, from sunny Southern California! The activity at the Jet Propulsion Laboratory is starting to pick up. Today was the opening day for "The Media Zoo," as some of us are calling it. Reporters and science writers from around the world are converging to cover Voyager 2's flyby of the planet Neptune. And I do mean the world. A reporter from "Asahi Shimbum" is sitting across the table from me. I've got a laptop. He's got a laptop fax machine.... There are also reporters from Holland, West Germany, Italy, and France. I've heard rumors that a Soviet journalist may be coming, too. The first formal press conference was held at 10 am Monday. It was mostly a "Hello there" from the head people of Project Voyager. However, we do have some interesting science to report. * One ring arc is now confirmed around Neptune. There may be more. They're looking. The arc, of course, is made of tiny particles of dust, probably ranging in size from dust motes to boulders the size of a Volkswagen Beetle. The arc we have seen, however, is not a smooth arc. It is clearly made of "clumps" of material. It looks like a necklace made of enlongated beads. * Neptune is a lively planet. In fact, it is starting to look a lot like Jupiter, only blue. It has a Great Dark Spot. The GDS is the same size relative to Neptune that the Great Red Spot is to Jupiter. It is also in the same latitude, -20 degrees, as the Great Red Spot is on Jupiter. It is ALSO "redder" than the surrounding Neptunian atmosphere. The GDS may be a hurricane. If so, it is one humongous hurricane. It's the diameter of Mars. * Triton, Neptune's big moon, is going to be one hell of a kick in the pants. Voyager 2 is still about 4 million miles away from it and we are already seeing markings on its surface. Dark splotches near its equator; some reddish markings near the south polar area; some white-looking streaks elsewhere. The atmosphere, if it is there, is quite clear, it seems. [Note: on the live TV monitors Monday morning, some of us reporters saw what LOOKS like a "feature" on Triton that seems to hang above the terminator. This could be an artifact, a blemish on Voyager's TV camera--or real. A high methane cloud in Triton's atmosphere? A plume from an ammonia volcano? Nothing? Who knows? Jonathan Eberhart of "Science News" and I are betting on a peanut butter volcano on Triton. Stay tuned.] The next item for your enjoyment is an article I have written for my old home town newspaper, the Ventura, California "Star- Free Press," based on an interview with Dr. James Warwick. Ta ta! ---------------------------------------------------------- TODAY'S GEE-WHIZ FACT: Each Voyager spacecraft consists of about 65,000 separate parts. That works out to the equivalent (in separate electronic components) of about 2,000 television sets. 1200 -*- 12263 21-AUG 23:35 Space & Technology RE: Voyager 2 Report (Re: Msg 12262) From: JOELDAVIS To: ALL One of the scientists for the Voyager 2 flyby of Neptune thinks there might be a connection between radio bursts from the planet, a giant storm in its atmosphere, and Neptune's moon Triton. The cause of the possible connection, however, is still a mystery. Jim Warwick, a slim, white-haired man with a ready smile and twinkling eyes, is the head of of the Planetary Radio Astronomy instrument (the PRA) aboard Voyager 2. This instrument detects radio waves naturally emitted by a planet, including from its magnetic fields and lightning in its atmosphere. Warwick is one of the real "characters" of the Voyager mission. Unlike most of his colleagues, he does not wear suits and ties to the Voyager science meetings. His preferred garb runs to casual shirts and slacks. He often is seen walking around the Jet Propulsion Laboratory in Pasadena, headquarters for the Voyager 2 flyby of Neptune, dressed in powder-blue sweat pants and a white pullover shirt. A crumpled fishing cap often sits atop his head. Warwick freely admits to "blabbing a lot" with reporters and science writers. "I must admit, I have trouble keeping my mouth shut when I'm supposed to," he says with a laugh. Warwick is no stranger to controversy. During Voyager 1's flyby of Saturn in 1980, Warwick suggested that his instruments might have detected radio emissions from some mysterious object embedded in Saturn's rings. That speculation was never proven. Now, Warwick believes that he and his team may see unusual patterns to the radio emissions coming from Neptune. Voyager 2 detected radio waves coming from Neptune on August 14, and those findings were confirmed a few days later. Scientists are now sure that the radio signals are coming from a magnetic field that surrounds Neptune. Magnetic fields have also been found surrounding Jupiter, Saturn, Uranus and of course Earth. Warwick's team has found that Neptune's magnetic field--and thus presumably Neptune--has a rotation rate of nearly 18 hours. Earth's rotation rate is 24 hours, that of Uranus is about 17 hours, and Jupiter's is about 10 hours. However, Warwick says that he and his associates have now found something unexpected. They have detected radio bursts from Neptune with a period of about 16 hours. They appear for a time, then disappear for about two days, and then appear again for several days. "There is a vague possibility that this 16-hour period is linked to the Great Dark Spot on Neptune," says Warwick, with excitement in his voice. The Great Dark Spot is a huge weather disturbance in Neptune's atmosphere, similar to the Great Red Spot on Jupiter. Neptune's moon Triton may also connected to the strange radio bursts, says Warwick. Triton, which is about as large as Earth's moon, orbits Neptune in what is called a retrograde orbit. Its path around the planet is clockwise, the opposite of the direction taken by other planets around the sun and other moons around their planets. Meanwhile, Neptune turns on its axis in a normal counterclockwise direction. The Great Dark Spot "catches up" with Triton more quickly than a standard Neptunian day. It and Triton are in the same relative position every 16 hours, instead of every 18-hour Neptunian day. Warwick thinks that the 16-hour period of the bursts might be the rotation rate of the interior parts of Neptune, which would then be rotating faster than its outer, visible atmosphere. The mystery is that the bursts are not regular. Some bursts do not appear at the expected 16-hour points. Warwick wonders if the missing bursts are caused by Triton. For example, the bursts occur when Triton and Neptune's Great Dark Spot are in the same relative positions. This takes place only when Triton is on the far side of Neptune, away from Voyager 2 and the Earth. It happens about every 48 hours, or two days. Warwick admits, with a smile, that there is still very little evidence for such a Triton-Dark Spot connection to the radio bursts. "We will be watching it very closely for the next several days," he says. If there is a real connection, the 16-hour period to the bursts will repeat at predictable times. One explantion for a Triton-Dark Spot connection might be found back at Jupiter. "It could be a phenomenon similar to what happens between Jupiter and its moon Io," he says. There, an electrically-charged "tube" of atomic particles connects the moon to the planet, and helps modify regular outbursts of radio waves from Jupiter. If this is the case, it would be only the second time such a "flux tube" has ever been found. However, whether it exists or not, clearly Jim Warwick is already in the middle of a new Voyager 2 mystery. And he is clearly enjoying it. -30- Copyright (c) 1989 by Joel Davis. ....... -*- 12269 22-AUG 18:23 Space & Technology RE: Voyager 2 Report (Re: Msg 12266) From: JOELDAVIS To: ALL Hello, all, from the Jet Propulsion Lab. I'm writing this about a half hour after the conclusion of this morning's press conference. The Big News today is: RING. Yes, indeed, Voyager scientists have now confirmed that at least one full ring of particles circles Neptune. The ring lies just outside the newly discovered moon 1989 N3 about 17,000 miles from the planet's cloudtops. This ring was first detected a few weeks ago, when it was seen only as an arc. Then it wasn't seen again. Voyager imaging scientists spent several weeks looking for the lost arc, and now those gallant raiders have found it... (sorry about that...). At the same time, the scientists have confirmed that the second ring arc is probably longer than first thought. They have found extensions to it, and Brad Smith, head of the Imaging Team, thinks that it too will turn out to be a full ring. This arc lies just outside the orbit of 1989 N4, about 22,500 miles from Neptune's cloudtops. The newly discovered ring is fairly uniform in structure, and is at least 30 kilometers (18 miles) wide. Clearly, there must be a second shepherding moon for this ring. But it has not been found yet. The arc is indeed clumpy, as I reported last night. Then there's Triton. The pictures today are getting better and better. It is still beyond the limit of resolving clear geological features, but we are seeing some tantalizing hints-- are those craters or impact basins? ridges? rilles? Is the leading hemisphere of Triton covered with a dark material, like Jupiter's Iapetus? We will know the answers on Saturday morning! ----------------------------------------------------------- TODAY'S GEE-WHIZ FACT: The resolution of the Voyager narrow-angle television cameras is sharp enough to read a newspaper headline more than a half- mile away. ==Joel . -*- 12293 24-AUG 08:50 Space & Technology RE: Voyager 2 Report (Re: Msg 12284) From: JOELDAVIS To: ALL Greetings from the Jet Propulsion Laboratory! My apologies for not getting anything to you yesterday. (A long day and a late nite...!) Yesterday morning's press conference produced no new surprises, like the ring announcement of Tuesday. But the news remains good. A few days ago Voyager 2 carried out one final tiny course adjustment. Yesterday Norm Haynes, the Voyager Project Manager, announced the results. Voyager 2 will now hit its target point in space with an accuracy of 33 kilometers, or about 20 miles. It will arrive at its closest approach to Neptune just 2.4 seconds away from it scheduled arrival time. That is now pegged at about 8:55 p.m., Pacific Daylight Time, on Thursday August 24. Remember, this is after travelling more than 4.4 billion miles for 12 years and four days. It has been compared to sinking a 2,260-mile golf putt. Not bad. Not bad at all. Some science results: * The Plasma Wave experiment has now detected emissions from Neptune. We do not yet know, though, if they have a 16 hour period like the radio emissions detected by the Planetary Radio Astronomy instrument. We need more data to determine that. * Neptune gets more and more interesting. It appears that a second dark spot in the planet's atmosphere has moved north in latitude. It is now in a region where the winds blow relatively more slowly. Another interesting point about this spot is that it has a bright central core. That white central area has changed in size and shape just over the last several days. Why, we don't know. * Triton, too, is beginning to look very tantalizing. There is clearly a bluish cast to the surface at one of its visible limbs. It is not an artifact. What is causing this is still a mystery. The reddish areas are almost resolving into - what? Can't tell yet. More for you later today--and tomorrow! ==Joel .-.... -*- 12298 24-AUG 17:22 Space & Technology RE: Voyager 2 Report (Re: Msg 12293) From: JOELDAVIS To: ALL Hello from the Jet Propulsion Laboratory in Pasadena, California. This morning's press conference has finished. Some of the high points: * Voyager imaging scientists have confirmed the discovery of two more moons around Neptune. Their tentative names are 1989 N5 and 1989 N6. The new moon N5 is 90 km in diameter (54 miles). N6 is may be no more than 50 km (30 mi) in diameter. N5's orbital period is about 7.5 hours; N6's is about 7.1 hours. What is particularly unusual is that moon N6 has an orbit that is inclined to Neptune's equator by about 4-1/2 degrees (plus or minus 1/2 degree). All the other newly discovered moons, N1 through N5, as well as the ring and "ring arc," lie smack in the equatorial plane. (Triton and Nereid, the moons known about before Voyager's arrival, have fairly tilted orbits. Also, Triton orbits in a retrograde [clockwise] fashion, and Nereid's orbit is extremely enlongated.) Brad Smith, head of the Voyager imaging team, says: "Ordinarily, a planet's gravity will force the orbits of moons to eventually line up with the planet's equator. Perhaps N6 began with an extremely inclined orbit, and now it is almost equatorial. Or, something is driving its orbit to be tilted." What the explanation really is, however, no one yet knows. The tilted orbit of N6 might be responsible for the broken, lumpy character of Neptune's ring and "arc." But Voyager scientists will need more data on the exact orbital elements in order to determine that. * Moon 1989 N1, discovered earlier this year, is LARGER than Neptune's moon Nereid. Nereid was discovered in 1949 by Gerard Kuiper, using a ground-based telescope. N1 is probably about 200 km in radius. Nereid's radius is about 170 km. This means that N1 is Neptune's second-largest moon (Triton is the largest, at 1,370 km radius) and Nereid is the third largest. Also, N1 is LUMPY. It is not a complete sphere. With a radius of @ 200 km, it is near the limit of radius that a heavenly body can have and still stay irregular. Any larger, and its own gravitational pull would make it spherical. * Rings--well, we are definitely talking about rings in the plural. Last night the spacecraft took a series of mosaic images along the putative circle of an outer ring, of which the known ring arc lies. It clearly discovered more material extending from the arc, further along the orbit. Only 10 percent of it is still unseen. Smith is sure that the material is really there, just too faint to be seen by Voyager. So we have an inner ring, confirmed 2 days ago, and the outer arc which is almost certainly a ring. Brad Smith says that the rings are very faint, probably about 7th or 8th magnitude--close to 9th magnitude, the limit of Voyager's cameras. He adds that a human riding along with the spacecraft MIGHT BARELY be able to see the rings with the naked eye. * Ed Stone, the Project Scientist, says that as of 9:40 am the spacecraft had NOT passed through Neptune's magnetic bowshock. That's the point where the solar wind hits Neptune's magentic field. However, the radio science, plasma science and magfield science people are seeing some "unusual activity" in Neptune's magnetic field. What the explanation of the activity is, is still unclear. The magnetic field is probably no stronger than 0.4 gauss, which is larger than Uranus's (and Earth's) and smaller than Jupiter. * For the first time ever, Voyager 2 has seen cloud SHADOWS on an outer planet. We saw two wonderful pictures that clearly showed shadows of Neptunian clouds falling on deeper cloudbanks. This is very important because scientists can use the cloud shadows to measure the distance from the upper clouds to the lower ones. It's simple trig; if you know the sun angle (they do) and the apparent distance from cloud to lower cloud (yes) you measure the the real distance. It works out to about 50 km or 30 miles. Some of the imaging team folks think it could be as much as 75 km. ==Joel Davis ----------------------------------------------------------- TODAY'S GEE-WHIZ FACT: Over a period of 145 months, from launch through end of Neptune encounter, the two Voyagers will have explored four planetary systems, traveled a combined total of 15.4 billion kilometers (9.6 billion miles), and taken 75,000 images. +++++++++++++++++++++++++++++++++++++++++++++++++++++++ Late update at about 1:30 pm. Voyager 2 has passed through the bow shock about an hour or so ago. Distance: about 30 Neptunian radii (743,000 km). This implies a magnetic field strength of only about .13 gauss, less than Earth's (I think). But that is very tentative. The scientists need to do a lot more data massaging to get the final number. -*- 12299 24-AUG 17:25 Space & Technology RE: Voyager 2 Report (Re: Msg 12298) From: JOELDAVIS To: ALL What is 276 pages long, published in paperback, with dozens of cute illustrations, beautiful astronomical photos, and "gee- whiz facts"? It's "The Voyager Neptune Travel Guide," written and edited by several members of the Project Voyager mission team at the Jet Propulsion Laboratory in Pasadena. It's the source of, among other things, the "gee-whiz facts for today" that I've included in some of my reports here. Hundreds of reporters from around the world have descended upon the lab to cover this final planetary encounter by the aging but still hardy spacecraft. And still more hundreds of JPL employees, though not working on Voyager, are interested in this exciting space age event. In order to provide all these interested people with a handy and compact reference book, Voyager Mission Planning Office head Charles Kohlhase put together the "Travel Guide." He and his staff had done a similar publication for the Uranus encounter in 1986, but they wanted this one to be different. "We wanted to get away from the 'standard government publication' look," Kohlhase said with a smile. "Instead, we wanted to publish a book that looked like one of those Audubon nature guidebooks." The "Travel Guide" isn't quite in that league--no color photographs, for example--but it is chock-full of information about Voyager 2, its four-planet mission, the planet Neptune, and the solar system. Kohlhase said it was a lot of work putting it together. It was also a lot of fun. "It took five of us, myself and four of my staff, about four months to put the 'Travel Guide' together," said Kohlhase. The hardest part of it was "getting the same style of writing from everyone," he added. "I told my staff, 'I want this to read like it was something written by Carl Sagan, or Isaac Asimov.' I wanted it to be readable, fun to read," he explained. Some people can write in that style. Others--especially those used to writing dry and wordy government documents and scientific reports--find it more difficult. Kohlhase's job was to smooth out the bumps in different styles, and come up with a completed book that looked good and read well. Judging from the large numbers of reporters and science writers at JPL who have been happily paging through their copies, he appears to have succeeded. And now you, too, can have your own copy. "We had 7,700 copies of it printed," explained Kohlhase. About 5,000 copies were reserved for the news media and JPL employees. The rest, said Kohlhase, are even now being shipped to the U.S. Government Printing Office. The GPO will sell the "Travel Guide" to the public through its bookstores around the country. To order the book, simply write or call the GPO in Washington, D.C. Ask for "The Voyager Neptune Travel Guide," stock number 033-000-01056-F. The "Voyager Neptune Travel Guide" will cost $12.00 a copy. That may seem a bit steep for a paperback. But at 276 pages, that works out to just four cents per page. That's not such a bad deal, for a travel guide to another planet. -*- 12307 25-AUG 23:49 Space & Technology RE: Voyager 2 Report (Re: Msg 12306) From: JOELDAVIS To: ALL Well....hello, all....It is now about 8:35 pm pacific time here on the west coast, in wonderful La La Land... I'm back at my parents' house after a 36+ hour day. No, didn't sleep much last nite. The pix of Triton are **** incredible... And we haven't yet seen the ultimate closeups, which were stored on the onboard tape recorder and will be downlinked tomorrow at about 6 am. But what he have now is amazing. Clearly, Voyager 2, that magnificent old spoace probe, has saved the best for last. Triton has upstaged everything. Hey, Chip Delany, are you watching?!! Here is the real "Triton"! "Wow! What a way to leave the solar system!" is what imaging scientist Larry Soderblom said this morning at the press conference. Z And he was right. What we have is a moon the size of our moon, which looks like it has pieces of our moon, of Mars, Ariel (one of Uranus's moons, remember), Io, Enceladus (of Saturn) and ghod knows what else. We clearly saw this morning-- * maria, but filled with frozen lakes of water/ammonia/methane, instead of frozen lava. * extension faulting, with graben (dropped blocks of surface between the upper edges of the faults) intersecting in a checkerboard pattern * evidence that much of the surfact of Triton is frozen "marshland" * at least one volcano, now extinct (probably?!) that erupted ice instead of lava. * an utterly bizaare formattion that looks like leopard spots. No one knows WHAT that is! Some other science results (as if that weren't enough!)-- Uranus does have a magnetic field, strength is about that of Uranus's, but I don't have the number in front of me. The field's magnetic orientation is like that of Jupiter, that is-- the lines of force come out of the pole in the physical northern part of the planet and go back in in the south. On Earth, by the way, it is opposite. The lines of force come out of the south and go into the north. Voyager 2 crossed the magnetic field's bow shock about 11:37 am on Wednesday. There will be more tomorrow at the Saturnday news conference, at 10 am. If possible, I will try to uploadc my next and last report from JPL. Depends on if I can get to a friendly phone. Oh--tomorow is VIP day for the Voyager Neptune flyby. Tons of celebrities, actors, policiticans--and SCIENCE FICTION WRITERS!-- will be at JPL to watch the screens and get informal briefings from JPL stgaffers. There's a rumorf going around that Asimov and Clarke will be there. But I'd be surpriosed if they were. You can certainly count on the LA SF contingent to be there --Niven, Pournelle (who has press credentials), etc, etc. Greg Bear is already here, with press credentials for the San Diego Union paper. So are Poul and Karen ANderson. It'll be fun. I head home Sunday morning, so tomorrow's report will be my last. Until then, "Fare Forward, Voyagers" --T.S. Eliot ==Joel -*- 12310 26-AUG 19:12 Space & Technology RE: Voyager 2 Report (Re: Msg 12309) From: JOELDAVIS To: ALL Hello from the Jet Propulsion Laboratory! This will be my last report for DELPHI, since I'm heading back home tomorrow--I have a book to finish writing... The press conferences will continue through Tuesday, so there will continue to be new data reported by the media. There were some delightful surprises revealed today at the morning science press conference. Something not too suprising were some of the narrow-angle closeups of Triton which came down from Voyager 2 last night and early this morning. They revealed no new surprises about that bizarre moon, though I guess that's fine. We have had plenty already from Triton! The closeups continue to show the strange mixture of terrain on Triton--icy plains, distorted oval-like structures that are almost certainly not craters (wrong topography), ridges, wrinkled areas, etc, etc. The scientists have refined their guesses of what the surface is made of, though. Almost certainly the visible white areas are nitrogen frost, along with "fresh" methane ice. The darker areas are probably methane ice which has been discolored by photochemical processes. One report about Triton at the press briefing this morning was new. We now have a first order idea about what Triton's atmosphere is made of. Dr. Sandel, a member of the ultraviolet instrument team, says that the UV emissions from the Tritonian atmosphere reveal the clear signatures of nitrogen molecules (N2) and nitrogen ions (N+). Also, the UV instrument followed an occultation of Triton by the star Beta Canis Majoris. (An occultation occurs when a planet or moon passes in front of a distant star. Think of it as a stellar "eclipse"). By watching the way the light of the star changes as it passes through the atmosphere, Sandel and his associates could learn more about what the atmosphere is made of at different depths. The result: Triton's atmosphere clearly contains nitrogen at high altitudes, and methane gas near the surface. Ed Stone, the Project Scientist, later remarked that it appears that the methane is really a trace gas in Triton's atmosphere, just like it is in Earth's atmosphere. Note, too, that our atmosphere is also mostly nitrogen. Now, on to Neptune. One clear surprise has to do with Neptune's magnetic field. It is highly tilted with respect to the the planet's spin axis. The tilt is at least 30°. It could be more. This finding was made by the plasma instrument people. As I noted yesterday, the magnetic north pole is located in the planet's northern hemisphere, like Jupiter's and unlike Earth's.) Hah! Bet you didn't know that. But it's true. If you live in Earth's northern hemisphere, the needle of your compass points at the Earth's SOUTH magnetic pole...). So, if the tilt is indeed 30 degrees, then Neptune's north magnetic pole is in a location analogous to southern Canada or in Alaska. Now, for rings. First, the photopolarimeter instrument, headed by Lonne Lane, tracked an occulation of the star Sigma Sagittarius by the planet's rings. The result will eventually a "map" of the thickness of the rings through a paticular slice of it. The resolution will be in meters, not kilometer, because the blinking on and off of the star is sampled very quickly. Lane reported, at a first cut, that the outer ring--the one with the clumpiness--has an inner core that is about 17 kilometers deep. There is also a broader component, extending away from the planet, which is about 50 km across. This outer ring, currently called 1989 RN1, is similar in many ways to Saturn's F ring, found by I think the Pioneer 11 spacecraft in 1979. Brad Smith, head of the imaging team, had more discoveries to report on. We have found at least two new rings, and maybe three. They are much fainter and more diffuse than the first two rings. Smith also showed two very dramatic photos, which showed the shadow of Neptune falling across the rings! It was very overexposed and grainy, not the highest quality--but it was a BEAUTIFUL picture! When it appeared on the screen, the entire press corps burst into applause. It was great!! And I think that sums up the atmosphere here at JPL, in the press room. So many of us are space freaks, space boosters, lovers of the sky and the stars. For us, this is not just a job, or even a way of life. It is a love, a deep and abiding love. To be here, for this final planetary encounter of Voyager 2, is such a high that I cannot describe it. I see old and familiar faces, and they are older, of course. Some of us have begun to gray in the last three years. Some faces aren't here this time around. Jules Bergman of ABC, for example, died of a heart attack a couple years ago. Roy Neal of NBC is retired. But it is like a family reunion still. Jim Long of Jim Long Associates sits across from me, with all his video taping equipment. Kelly Beatty of Sky and Telescope sits two rows of tables away. And on and on. It's a great feeling. And the camaraderie is wonderful. It is not all that surprising, I guess, that we ooh and ahhh at amazing pictures, and applaud the scientists at the end of the press conference. It is sad to leave. And I know I'll be back. Coming is Magellan, and Galileo, and Mars Observer, and Cassini... But there will always be only one Voyager mission. And it is coming to an end. ==Joel