Checking in at JPL
Posted by Emily Lakdawalla
21-05-2008 17:32 CDT
I drove in to the Jet Propulsion Laboratory to pick up my badge today and scope out the press area for the Phoenix landing event, from which I'll be blogging and doing webcasts. I was delighted to see that this year's badges aren't radioactive orange with huge black letters saying "PRESS," as they have been in past years. (Those might as well have said "DON'T TALK TO ME!") I was pretty much the first media person to show up, so I was able to pick a place to sit that has a good view of the TV monitors tuned to the NASA feed, and, more importantly, is out of the glare of the overhead lighting. The press room is (as usual for big events at JPL) in the museum attached to the Von Karman auditorium, so the lighting is designed for spotlighting museum displays. It's a bit glare-y, but it's also nice to sit and work and be able to look over my shoulder to the full-scale model of Galileo, and other such memorabilia. The press briefings are to be held in the auditorium proper, which contains a full-scale model of one of the Voyager spacecraft, an object that I regard with some reverence, like one might feel for the gold-and-ivory statue of Athena that once stood inside the Parthenon. Von Karman is no Parthenon, of course, but I hope you get my meaning.
All was pretty quiet; I saw a couple of random JPL personnel, and a couple of random media people, and that was it. I'm sure it will be much busier when I check in tomorrow. I'm still planning on trying a Ustream chat from there at 13:00 my time (20:00 UTC) tomorrow. I tested out the Internet connection and everything seemed to work.
I'm putting the finishing touches on a timeline of all the events on landing day. Here's the latest info that I have. Please contact me if you notice any errors or points of confusion.
Event times are given in Spacecraft Event Time (SCET), which is the time according to the spacecraft's clock, and also Earth Received Time (ERT), which accounts for the 15 minutes and 20 seconds it takes radio signals to traverse the 275 million kilometers (171 million miles) separating Earth and Mars on landing day. ERT is given both in Universal Time (UTC) and Pacific Daylight Time (PDT). To follow a realtime simulation of the landing events, visit http://dmuller.net/phoenixor its mirror site. To watch a realtime simulation of the landing events, download the "Heads-up display" animation from the Phoenix website.
Touchdown should happen at 23:38:32 SCET / 23:53:52 ERT (UTC) / 16:53:52 ERT (PDT), give or take 46 seconds.
|SCET||ERT (UTC)||ERT (PDT)||Event|
|May 22 18:30||May 22 11:30||News briefing|
|May 24 19:00||May 24 12:00||News briefing|
|May 25 04:25:00||May 25 04:40:20||May 24 21:40:20||Gravitational tug of Mars exceeds that of the Sun|
|15:30:00||15:45:20||May 25 08:45:20||Trajectory Correction Maneuver Opportunity TCM6X|
This is the final opportunity for Phoenix to adjust its course toward its landing site.
|21:29:20||21:44:40||14:44:40||Flight Operations Readiness Poll|
In the control room, every station will be "polled" as to their status.
|22:00||15:00||NASA TV non-commentated coverage begins|
Broadcast on NASA TV Media Channel
|22:30||15:30||NASA TV commentated coverage begins|
Broadcast on NASA TV Public Channel
|23:21:12||23:36:32||16:36:32||Mars Express starts listening for Phoenix|
Mars Express will be listening using an instrument originally designed for communication with the lost Beagle 2 lander.
|23:22:40||23:38:00||16:38:00||Begin "bent-pipe" relay from Phoenix to Goldstone DSN station via Mars Odyssey|
Mars Odyssey will serve as a communications relay for Phoenix, sending its telemetry straight to Earth at 8 kbps.
|23:22:41||23:38:01||16:38:01||Green Bank, WV, radio telescope starts listening for direct UHF from Phoenix|
|23:22:54||23:38:14||16:38:14||Mars Reconnaissance Orbiter starts listening for Phoenix|
|23:24:13||23:39:33||16:39:33||Cruise stage separation|
The part of the spacecraft that provided power and allowed course corrections for Phoenix during its nine-month trip to Mars will fall away, leaving the lander still protected behind a heat shield and capped by a backshell.
|23:24:16||23:39:36||16:39:36||Phoenix starts broadcasting UHF carrier|
Although it contains no specific information, the carrier signal from Phoenix will tell Earth controllers if the spacecraft is alive, or in trouble, by its detection or non-detection by all the spacecraft and ground stations that are listening for it. Doppler tracking of the carrier signal from both spacecraft and ground stations will provide very specific information on the position and velocity of Phoenix throughout the landing.
|23:24:43||23:40:03||16:40:03||Turn to entry attitude starts|
The spacecraft will turn so that the heat shield protects it as it speeds through the Martian atmosphere.
|23:26:10||23:41:30||16:41:30||Turn to entry attitude complete|
|23:29:13||23:44:33||16:44:33||Phoenix starts broadcasting UHF telemetry|
Mars Odyssey will relay these data, containing information on the health and status of the spacecraft, to Earth through the "bent-pipe" link with the Goldstone Deep Space Network station.
|23:46:22||16:46:22||Time to press "play" on heads-up-display movie|
Download the heads-up display video from the Phoenix websitein advance, and press "play" at this point to watch the events in real time.
Phoenix enters Mars' atmosphere.
|23:32:02||23:47:22||16:47:22||Start plasma blackout|
As hot plasma surrounds the spacecraft, communications will likely be temporarily unavailable.
|23:34:02||23:49:22||16:49:22||End plasma blackout|
|23:34:22||23:49:42||16:49:42||Mars Odyssey switch to 32 kbps|
The bitrate of the Odyssey link will increase by a factor of four as the events start to happen more quickly.
The HiRISE camera on Mars Reconnaissance Orbiter will attempt to catch a photo of Phoenix as it descends through Mars' atmosphere. The Mars Reconnaissance Orbiter mission gives only a small chance of this imaging attempt succeeding. It will take about two minutes to capture the image, during which Phoenix may or may not pass through the HiRISE field of view.
|23:34:55||23:50:15||16:50:15||Parachute deployment |
(Plus or minus about 13 seconds) It takes the parachute 5 seconds to deploy fully.
|23:35:10||23:50:30||16:50:30||Heat shield jettison|
(Plus or minus about 13 seconds)
(Plus or minus about 13 seconds)
(Plus or minus about 46 seconds)
(Plus or minus about 46 seconds) The lander will switch from its low-gain UHF antenna to its high-gain helix antenna, which will cause a communications gap lasting 6 seconds.
|23:37:49||23:53:09||16:53:09||Lander separates from backshell|
(Plus or minus about 46 seconds) The backshell and its attached parachute will crash to the ground separately, and will probably be the first things to be spotted from orbit.
|23:37:52||23:53:12||16:53:12||Descent thrusters throttle up|
(Plus or minus about 46 seconds)
|23:38:14||23:53:34||16:53:34||Constant-velocity phase begins|
(Plus or minus about 46 seconds) Phoenix should descend smoothly, at constant speed, on its thrusters.
(Plus or minus about 46 seconds) Landing will occur at approximately 16:15 local solar time.
|23:39:35||23:54:55||16:54:55||Phoenix radio off|
(Plus or minus about 46 seconds) After this time, Mars Reconnaissance Orbiter and Mars Express will stop recording Phoenix' transmissions.
|23:51:13||May 26 00:06:33||17:06:33||Solar arrays open|
|May 26 00:12:40||May 26 00:28:00||17:28:00||Mars Reconnaissance Orbiter playback (41 minutes)|
Data will not be ready for analysis for several hours after the playback ends.
|May 26 00:14:40||May 26 00:30:00||17:30:00||Flight Operations post-landing poll|
Teams will report on the status of the spacecraft.
|May 26 00:14:45||May 26 00:30:05||17:30:05||Mars Express playback (43 minutes)|
Data will not be ready for analysis for an hour after the playback begins. The playback will be repeated two more times to ensure all data is received on Earth.
|May 26 01:28:31||May 26 01:43:51||18:43:51||Begin "bent-pipe" relay from Phoenix to DSN via Mars Odyssey|
If everything goes well, this transmission will include the first images, taken of the solar arrays, to check the status of their deployment.
|May 26 04:00||May 25 21:00||News briefing|
|May 26 18:00||May 26 11:00||News briefing|
Mars Reconnaissance Orbiter HiRISE plans two imaging attempts for the first sol; however, the odds of success are low.
|May 27 18:00||May 27 11:00||News briefing|
|May 28 18:00||May 28 11:00||News briefing|
|May 29 18:00||May 29 11:00||News briefing|
|May 30 18:00||May 30 11:00||News briefing|
Mars Reconnaissance Orbiter HiRISE plans another imaging attempt for the fifth sol of Phoenix' mission. The odds of spotting Phoenix are much higher for this attempt than for the sol 1 attempts, because they will have better navigational information with which to target their photos. However, even if successful, the photo may not be ready in time for this press briefing.
Finally, I want to mention that a sharp-eyed reader noticed an error in one of the landing site maps I posted yesterday -- the longitude labels on the colorful geologic map were off by half a degree, which meant that the ellipses I'd plotted on that map were also off by half a degree. Here's the repaired map; I also updated it in the previous post.
Phoenix is scheduled to land May 25, 2008 in a region above Mars' Arctic Circle. Its 3-sigma landing ellipse (largest yellow oval, the region in which there is a 99% certainty that the lander will come to rest) is about 100 kilometers long and 19 kilometers wide, centered at 68.151 degrees north, 233.975 degrees east. This map is current as of May 19, 2008, a week before the landing, and accounts for a late northwestward shift of the target point. Credit: NASA / JPL-Caltech / Washington Univ. St. Louis / JHU APL / Univ. of Arizona / Tim Parker / Emily Lakdawalla
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