Other than where you follow it, I'm just wondering when you all follow it ... when does the landing occur in your mind and imagination? Clearly NASA TV will be on Earth Received Time, but your mind (and the real-time simulation) can be tuned to Spacecraft event time (so far I see about an even split between ERT and SCET on the simulation).

Daniel

My guess too is that the electric power budget overrides the slim possibilities of having the chance of a hop that saves the mission. Phoenix will be landing just before night fall, and they even switch off the lander radio one minute after touchdown, arguably to save energy until the solar panels are deployed and the sun rises again. And heating up the fuel at a later stage may just consume too much energy

Glad you didnt simulate the "lander separation" step

Does anybody know if this happened, and if it affects the landing and/or entry interface time?

Anyway, based on the EDL movie and previous timeline, I can add the following additional events that I have worked out (thus no guarantee for accuracy) .. all in UTC:


L....| SCET.................| ERT..................| Event
.....| 23-May-2008 13:18:00 | 23-May-2008 13:33:09 | Enters Mars Sphere of Influence (SOI)
.....| 25-May-2008 11:25:00 | 25-May-2008 11:40:20 | Gravitational tug of Mars exceeds that of the Sun
.....| 25-May-2008 22:00:00 | 25-May-2008 22:00:00 | NASA TV raw coverage (media channel) starts
.....| 25-May-2008 22:30:00 | 25-May-2008 22:30:00 | NASA TV coverage (public channel) with comments
.....| -------------------- | 25-May-2008 23:31:13 | Entry Interface in Spacecraft Event Time
.....| -------------------- | 25-May-2008 23:38:32 | Landing in Spacecraft Event Time
.....| 25-May-2008 23:29:13 | 25-May-2008 23:44:33 | Mars Express acquires Phoenix signal
-450 | 25-May-2008 23:31:02 | 25-May-2008 23:46:22 | EDL movie - press play now
-410 | 25-May-2008 23:31:42 | 25-May-2008 23:47:02 | Maximum speed
-358 | 25-May-2008 23:32:34 | 25-May-2008 23:47:54 | Peak Deceleration
-335 | 25-May-2008 23:32:57 | 25-May-2008 23:48:17 | Peak Heating
-236 | 25-May-2008 23:34:36 | 25-May-2008 23:49:56 | Enters 3-sigma landing ellipse if landing is nominal
.....| 25-May-2008 23:38:32 | 25-May-2008 23:53:52 | Touchdown on Mars [46sec]
+006 | 25-May-2008 23:38:38 | 25-May-2008 23:53:58 | Helium venting [46sec]
+620 | 25-May-2008 23:41:33 | 25-May-2008 23:56:53 | Mars Express looses Phoenix signal
.....| 26-May-2008 02:14:40 | 26-May-2008 02:30:00 | Possibly first picture of Phoenix solar panel


Daniel

EDIT: neat revised logo Doug, very fitting!

needless to say the landing scenario in the EDL movie does NOT match the nominal timeline published earlier this week. Doug, you're gonna be landing a few times on Mars (the movie, the script which follows the nominal timeline, and NASA TV)

What are your memorable UMSF phrases and headlines you remember that sent shivers down your spine? Here's my short-list:
Apologies if such a thread already exists and I missed it ...

"At this moment we should be on the ground ... stand-by" (Spirit landing)

"Go Phoenix" (final launch poll)

"We have picked-up the carrier signal from Huygens"

"Given the burn performance so far, we should have entered orbit around Saturn by now" and
"The Doppler has flattened out" (Cassini SOI)

and from manned spaceflight:
"bye bye" ... last comm of crew of Columbia STS-1 before reentry blackout on the maiden shuttle flight
"Challenger ... Houston ... ATO ATO" (abort-to-orbit as one Challenger main engine shuts down prematurely)

A rather long post with several replies:


I agree it's by far the best. I actually wrote my script because real (i.e. not teaser) animations like that were hard to find, and I cannot recall any landing where there is some sort of speed/altitude continuous progress shown.
Actually, I found the animation COMFORTING rather than TERRIFYING ... I did test-"land" my script, and I knew speed and altitude will go down to 0 at landing (I programmed it, didn't I), but the numbers were running so fast until touchdown that I really thought it's gonna "crash".



IMHO the best space related background music is still from the IMAX movie "Hail Columbia". Full of power and optimism. Unfortunately it's not freeware :-(




Thanks Svetlio. Yes I saw it as well, but the Phoenix team's own EDL gives me altitude and speed second by second. Will spend most of my weekend plugging the numbers from there


I will do that

We are now 8 days 22 hours 20 minutes (ERT) from landing on Mars. Altitude above Mars 2.08 million km, distance to fly 16.9 million km. It was a mere 286 days ago when the final launch poll heard "Go Phoenix".

Daniel

That can, of course , be done! I can insert an 'event' into the realtime simulation that tells you when to press play so that it tallies with the progress of the script ...

OR, if you have both the script and the movie downloaded on your PC, then the script can tell the movie to start at the appropriate time (possibly lags 1 or 2 secs as the loading of the movie takes slightly different lengths of time depending on the computer etc). But this only works if BOTH the script and the movie are on your PC. DONT rush to download the realtime simulation yet, it will run out of data in 3 hours ...

Would people be interested in the above functionality? Requires some reprogramming but (fingers crossed) should be able to be done.

now can anybody employ me to do these things ... it's great fun and distraction from real work

Oh yes, I dont suggest we all watch that movie in realtime on the web, the server there may not make it

Doug ... yeah for once it's good to have a big cubicle with all that technology ... I'm still trying to figure out whether to watch from home (large monitor) or go to the DSN visitor center nearby (=4 hours drive, that's next door in Australia)


Daniel

My first live Mars landing was Beagle2 ... I was out of reach of live coverage for Pathfinder and MPL.

My first live out-of-this world viewing was Giotto at Halley. Got me hooked. And saw (and especially HEARD) Ulysses launch in person at Cape Canaveral - so much happened in the meantime and the craft is still alive (somewhat). But I also remember running home from school for the first scrubbed launch attempt of Columbia STS1 ... it was a Wednesday afternoon in Europe, no school on Wednesday afternoons :-)

Daniel

The following animation has been put up at http://phoenix.lpl.arizona.edu/videos.php#edl_hud, very impressive:


Now all that's missing is a second craft filming Phoenix during its landing and broadcasting live on HDTV

Daniel

Thanks Kwan for the links. Interesting reading, and please do make the orbitersim.com Phoenix model available for public use :-)

Meanwhile, the following animation has been put up at http://phoenix.lpl.arizona.edu/videos.php#edl_hud, very useful for my project, and impressive as is:


I will still use your references for the time from Entry Interface to plasma blackout.

Daniel

Looks like the host server has problems as I cant access the page now either and the host's own webpages are very slow. Better now than in 3 weeks. Anyway, I will arrange for a mirror site with a different host and advertise it here once it's up and running in a couple of days ... planned to do that anyway but not so early on.
Daniel

Hmmm it works for me. Maybe you hit a busy spot? Try again at http://www.dmuller.net/phoenix

An update with 22 days and 5 million kilometers to go ...

First my thanks to Emily for mentioning the simulation on her Planetary Society blog. It attracted a large crowd (avg 100 visits/day) and by now I get a steady stream of visitors to the simulation from people who have bookmarked the site. Great!

As for the script, all functionality is now included, including DSN coverage, virtual commentary during landing and a bigger font for the numbers. At the moment, the script is in "Spacecraf Event Time", and "Earth Received Time" will be enabled shortly.

The challenge now is to fine-tune the data during the first part of the atmospheric flight, in particular from Entry Interface to Parachute deployment. Therefore, again, if anybody has information on the following, please share them with me ... pretty please ...

(1) Precise timing for TCMs 4, 5, 6 and 6X

(2) Anticipated nominal altitude as a function of time and speed as a function of time (time being from Entry Interface or landing). Trajectory reconstructions for Spirit, Opportunity or Beagle-2 would be welcomed too ... I saw references made to them on the net, but havent actually found one :-( I did, however, find a neat one for the Huygens landing on Titan

Piecing together the snippets of interviews found on youtube just doesnt give the whole picture.

Also, if you manage / work for / represent etc a spaceflight educational outreach position (and dont have internet access there), I can create an offline version of the script. At last count, it's already heading that way to 3 such organizations on 3 continents.

Hi Emily ... I dont "know" the answer(s) either but I have a few points that could get you started.

The Moon has been used to help accelerate spacecraft out of Earth orbit: ISEE-3/ICE in the early 80s, and at one stage was also planned (or still is) for Bebi-Colombo. But those are "circle the Earth a few times first" types of departures, not the usual straight out (like Phoenix).

I see the following issues using the Moon for straight out departures:
1) Precision ... you'd have only a few hours to detect and correct any launch errors. These errors would grow in size during a flyby at the Moon.
2) Launch window ... would the Moon (ever) be in a correct position during a launch window? you would need the position of the Moon AND the target destination AND the weather to cooperate.
3) Effect ... the accelerating effect may not be too great as the Moon aint got all that much mass

As for Earth returns: Galileo used an Io swingby during its Jupiter orbit insertion to save a bit of fuel. But on Earth, I'm not sure that it would enable you to carry a lighter heatshield if you can slow yourself a little using the Moon for a direct entry. Earth orbit insertion would still require a retro-burn (engine and fuel add weight), or a heatshield for aerocapture. You also reduce the arrival window for your mission

Hope that gets it started. And its an interesting question, looking forward to the full answer as well.

BTW thanks for mentioning my Phoenix countdown on you Planetary Society blog ... it attracted heaps of visitors!

Daniel

Beautiful! I'll add information gathered from those slides to my (planned) New Horizons' script, once I'm done working on the Phoenix real-time simulation script ... if I may do so, of course. Good luck Alan with NH!

Daniel

Thanks infocat ... I used that document, and duly cited it, for some of the information used on my real-time Phoenix simulation script. Slipped my mind to look at it again to answer that question. Looks to me like we are going with "Page 14, Figure 13 EDL Communications Geometry, Open Launch" as shown in that document.

But yes it is a premission document, some things changed quite a bit. More information would definitively be a great plus. Emily mentioned the script on her Planetary Organization Blog, and I've had 250 site views on Saturday alone.

Daniel

Someone asked whether Phoenix will land heading NW (diagonally up) or SE (diagonally down) on the landing ellipse. I assumed the formed but after some research seem to have been wrong! Here's the reasoning I figured out and gave that person, but did I miss something?:

Mars, on 25 May, is about 7.4 million km above the eclipitc. Phoenix, when it launched, was right on it (by definition). So at the moment it is approaching Mars from the South, will cross it's equator and head North. Mars' gravity will pull it back South just a little. So it will land from the North West and head South East (from higher to lower) in the landing elipse. Compare the following 3 images (load them, then use back / forward in your browser):

http://space.jpl.nasa.gov/cgi-bin/wspace?t...=1&showsc=1
http://space.jpl.nasa.gov/cgi-bin/wspace?t...=1&showsc=1
http://space.jpl.nasa.gov/cgi-bin/wspace?t...=1&showsc=1

That's Mars seen from above (in 1 minute intervals), and you can see Phoenix heading "down" again as it starts descending through the atmosphere
That's what I can figure out, at least

When Phoenix meets Mars, the spacecraft will have a lower orbital speed around the Sun than Mars. Why? because the Phoenix orbit would take it all the way back to where it came from ... Earth (though Earth wouldnt be there at that particular time). So, in theory, Phoenix would have to speed up to match Mars' orbital speed and "stay" with it.

BUT

Phoenix (or any other craft going there) will get very close to Mars, and you want to stay there (land or orbit). So you cant fly "along" Mars because it's gravity would pull you in if you just match its orbital speed at close distance. The issue now is that you are too fast for Mars to capture you in its orbit, or land at a decent speed, so you have to slow down your orbital speed around MARS (not the Sun). Close to Mars, the gravitational force of Mars exceeds that of the Sun anyway, so you dont really care whether your orbital speed around the Sun goes up and down as you enter an orbit around Mars or land on it (it's a whole different story though if you use Mars for a swing-by).

Phoenix will reach the point from where the gravitational force to Mars exceeds the one to the Sun on 25-May-2008 11:25am SCET UTC, 12 hours before landing, at a distance from Mars of about 139,000 km

Phoenix will slow down its orbital speed around Mars as follows:
1. friction (glowing as it streaks through the atmosphere)
2. parachute
3. retro rockets for the last 500m or so only
4. ground impact

The remaining engine firings, TCMs, are not meant to slow the craft down to Mars, only to make sure it hits the atmosphere where it is supposed to.

Phoenix landing times are as follows:
Entry interface expected on 25 May 2008 23:31:12 UTC, landing expected on 25 May 2008 23:38:32 UTC Spacecraft event time
Entry interface expected on 25 May 2008 23:46:32 UTC, landing expected on 25 May 2008 23:53:52 UTC Earth received time

Any good reference on the latest analysis of that "encounter"? It would make a good line on my website. Just by looking at it, it remained the closest flyby of an outer-planet moon until Galileo's Io swing-by during its Jupiter orbit insertion.

Mark, you could also use formatting (e.g. bold: prime operations (flyby, science orbit) :: (normal): cruise, occasional observations :: italics: standby, hibernation) whilst you collect data stream records. Probably easier to script in php than fiddling with column widths, at least for the time being

Only to nearly crash into a then-unknown but photographed moon, possibly being Janus or Epimetheus

Unfortunately not (yet). The only information I have regarding this is the info that can be extracted from the charts above, with max deceleration being between 7 and 9 g's. I am trying to get more info from the Phoenix team / JPL, and will incorporate it into the script if I get good enough information to do so. Information on the atmospheric section of the flight (events, speed, altitude, downrange, deceleration etc) is pretty sparse at this time, and difficult to extrapolate from the little I have.

It will get tricky once you get into the Solar probes. Some of the really old ones are still alive but not actively used, like Pioneer 6, which launched in 1965 and radio contact was last established in 2000, and could be established again if the will, money and DSN availability was there. I think the term is "extant" for such probes. Those old probes were spin-axis stabilized, which turned out to be really stable, and dont rely on (much) attitude control maneuvers.

Does anybody know which other crafts are "extant". Quite a few missions were "switched off" rather than "lost", and those could theoretically be reactivated (Giotto comes to mind).

Then there is also the Deep Impact flyby craft (or was it Stardust?), which I heard is being sent to a new target.



Mark, as for plotting your graph, I definitely think that the journey to the target is part of the mission. Regarding re-arranging the columns, you could do the whole thing in Excel (if you copy it from IE then you wont even loose the urls) and drag and drop cells as you please. When done save as a html file, or create an html generating formula (e.g. ="<tr><td>"&A1&"</td><td> ...."; might get tricky with links though). A possible way that you can arrange them is to place the same mission into
the same column so it's easy to see the date range of a mission being active, downside is that you'll have gaps and can't see which crafts are the oldest.

On that note, can I link to your site from my interplanetary spaceflight website?

Phoenix is now 34 days 19 hours from Mars, still has 66 million km to fly. Current altitude above Mars 8 million km.

Phew ... well we can trust NASA on that, can't we ... I hope it wasn't them who posted a picture of Phobos above Mars in the article, possibly suggesting that it was Phobos that has a 1 in 45,000 chance of hitting Earth