Hi Fellow water-dump-fans In order to aid Ted's research into water dump dynamics, here's some old messages after my first water dump observation. Regards Willie ---------- Forwarded message ---------- Date: Fri, 28 Jun 1996 19:47:25 +0200 (GMT+0200) From: Willie Koorts <wpk@saao.ac.za> Subject: STRANGE OBSERVATION OF STS-78 !! SIDEWAYS j ?? Hi Folks I just had the most amazing sight of STS-78. It was a very good pass, practically overhead (61 deg.) 1 hour after sunset. The conditions were very favourable, clear from horizon to horizon and excellent sky transparency - the site is the observing outstation of the South African Astronomical Observatory. At the predicted time at about 15 deg. elevation a little white cloud appeared. While still scanning the skies in that direction, we noticed some movement towards us of this "white cloud". The movement become faster and much more noticeable and a bright spot started appearing on the southern end of the cloud. This light spot became possibly 1 st Mag by the time of culmination and the "tail" was easily 2 degrees long at this stage. By now the 3/4 moonlight was becoming a nuisance but the "tail" was almost all the way visible till shadow. The appearance of it was exactly like a lower case "j" on it's side with the dot being the shuttle and the character the "tail". We were 2 persons sighting it and we both remember the kink in the tail in different directions. The cloud was fanning open away from the shuttle. Something like this: (Let's say the kink was towards the direction of movement) O----------::::::;; ;: :: | | V Direction of movement. Willie ---------- Forwarded message ---------- Date: Sat, 29 Jun 1996 00:36:11 +0200 (GMT+0200) From: Willie Koorts <wpk@saao.ac.za> Subject: RE: STS78 STRANGE OBSERVATION On Fri, 28 Jun 1996 PMALEY@GP808.jsc.nasa.gov wrote: > Since there was not a time posted, I can say that today this particular > supply water ejection began around MET 8d 01h 06m and ended at 8d 02h > 23m. If I did not make a mistake in doing the conversion to UT, this > corresponds to June 28 at 17:55 UT and ended at 19:12 UT. Either way, I > checked the ground track map and it shows the orbiter passing over > Namibia on an ascending track at the time. > > Paul Maley > > pmaley@gp808.jsc.nasa.gov Sorry for leaving out one of the most important parts of reporting anything. Here is a copy of the predictions ala Greg Roberts: (elems slightly old) For station Sutherland at West Longitude = 339.19 and latitude = -32.378 Schedule for 96036A #23931 on 960628 Age= 3.84 days 96036A UTC AZM EL RNG HGT R.A DEC PHA DMAG 16:39:40 290.6 0.2 1859 272V 31:17 17:11 110 70.6 16:40: 0 290.3 1.4 1718 271V 31:21 16:11 92 8.2 16:40:20 289.9 2.9 1576 271V 31:25 15: 3 91 4.5 16:40:40 289.4 4.4 1435 271V 31:30 13:47 90 3.1 16:41: 0 288.8 6.2 1294 271V 31:35 12:19 88 2.4 16:41:20 288.1 8.2 1154 271V 31:40 10:36 87 2.0 16:41:40 287.3 10.6 1015 271V 31:47 8:29 86 1.7 16:42: 0 286.1 13.6 877 271V 31:54 5:50 84 1.5 16:42:20 284.4 17.4 742 271V 32: 3 2:21 83 1.4 16:42:40 282.0 22.6 610 271V 32:15 -2:29 82 1.2 16:43: 0 277.9 30.0 486 270V 32:33 -9:39 80 1.1 16:43:20 269.7 41.5 376 270V 33: 1 -20:59 79 1.1 16:43:40 247.6 57.8 298 270V 33:58 -38:38 78 1.1 16:44: 0 185.8 64.5 278 270V 36:17 -57:39 76 1.1 16:44:20 145.3 48.9 329 270V 39:44 -59:19 75 1.1 16:44:40 132.4 34.5 425 270V 41:30 -50:37 74 1.3 Hmmmm.. Our times does not exactly agree. Is your information from NASA's official schedules? Two more questions: How are these MET timings reckoned? How long does such a dump normally take to sublimate and become invisible? ---------- Forwarded message ---------- Date: Fri, 28 Jun 1996 20:14:50 -0500 From: Mike McCants <mikem@fc.net> To: wpk@saao.ac.za Subject: reply >How are these MET timings reckoned? Launch for STS 78 was 10:49EDT on June 20 = 14:49UT on June 20. Add Mission Elapsed Time to that to get actual time. Say hello to Greg. Mike ---------- Forwarded message ---------- Date: Sat, 29 Jun 1996 00:02:38 -0500 From: "McDonald, Teresa A." <TMCDONAL@GP808.jsc.nasa.gov> To: Willie Koorts <wpk@saao.ac.za> Subject: RE: STRANGE OBSERVATION OF STS-78 !! SID Hi Willie, According to the logs in Mission Control, that was indeed a water dump. The shuttle is operating normally. I guess the light reflected off it in an unusual way, causing the vapor to shine so brilliantly. I can't explain the unusual "j" shape; perhaps the orbiter was using an RCS thruster to change attitude and the vented water caught a "breeze." Here are the facts, according to my contact in Flight Design and Dynamics: A water dump took place from UTC 180/15:55 through 180/17:12. This is from 5:55 pm to 7:12 pm South Africa time. Your sighting was at about 6:45pm. Best wishes, Terry McDonald ---------- Forwarded message ---------- Date: Sun, 30 Jun 1996 09:44:17 -0500 From: "Maley, Paul D." <PMALEY@GP808.jsc.nasa.gov> Subject: re;STS78 STRANGE OBSERVATION The observation Willie Koorts made was definitely a water dump. I did make an error in my quick conversion from MET to UT as I was in a hurry at the time. The water dump time began at 180days 15h 55m and ended at 17h 12m UT. There was also a Flash Evaportor System (FES) core flush done earlier but it was out of the scope of your observation. Explanation of the "j" shape is not what was forwarded to you by T. McDonald. In fact, the "j" shape is easily explained by the vertical orientation of the dump toward the earth. As water is propelled downward, the particles farthest down from the orbiter speed up in the forward direction. This is the same effect of ejecting a small satellite downward. Each water particle becomes a small satellite. In a lower orbit it will naturally accelerate faster than the orbiter. I first observed this about 12 years ago and have a brief video of that which I will be showing at EUROSOM 2. The water dump particles freeze upon ejection into space, are dumped and spread out in a continuous stream which in the past have actually been seen (by the cockpit crew) on one occasion to recontact the orbiter. They can last a number of orbits before decaying. I was the originator of a Detailed Test Objective a number of years ago after observing the vastness of the water dump since it is indeed many kilometers long. This was not known until I observed it way back then. Since that time others have observed water dumps and describe varying lengths and appearances. They are always interesting to see and under a dark sky with no haze, clouds, moon, etc. give the impression of a small moving comet. Paul Maley pmaley@gp808.jsc.nasa.gov ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
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