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Posted by: nprev Jun 23 2012, 05:32 PM

We're now 45 days from landing, so as of 23 Jun please post all comments related to the end of the transit to Mars here.

Go Curiosity!!!!

Posted by: Stu Jun 23 2012, 06:54 PM

Approach Phase.

Blimey.



Buckle up, people.

Posted by: imipak Jun 23 2012, 10:23 PM

...and extinguish all cigarettes? Doesn't time fly in retrospect, but crawl when looking forwards...

Posted by: Oersted Jun 25 2012, 12:54 PM

Good write-up by elakdawalla here:
http://www.planetary.org/blogs/emily-lakdawalla/2012/06221711-how-curiosity-land-part-1.html
-Looking very much forward to the upcoming parts!

Just have a question, though. It says the "nose will tip upwards by about 20 degrees" when the first set of mass balances are thrown. I thought the nose would tip downwards, to enable a bit of lift by the airshell and heat shield? I.e. that the "plate" of the spacecraft would "lie more flat", in stead of "standing more on its edge", with respect to the Mars gravity field.

Posted by: mcaplinger Jun 27 2012, 03:41 AM

The lift vector/bank angle is steered during entry in whatever direction is needed to hit the aim point. See http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/41708/1/08-0255.pdf -- section 4.

Posted by: Lightning Jun 27 2012, 09:06 AM

A third (and short) TCM occured yesterday. The spacecraft gained 50 mm/s, shifting as planned the landing site to about 7km toward Sharp Moutain.

Posted by: Oersted Jun 27 2012, 10:19 PM

Ok, I found the answer to which way the entry configuration is influenced by the shedding of the cruise balance masses. As I thought, the "nose" of the spacecraft does indeed tip downwards by twenty degrees, to enable a guided lifting entry:

Described on p. 2 of
"Mars Science Laboratory. Entry, Descent, and Landing System Overview"
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/41629/1/10-1775.pdf

mcaplinger, yes, the spacecraft doers indeed maneuver around during entry, but the jettison of the CBMs gives it a new stable configuration, with the nose pointing downwards so the lift vector points slighty forwards.

- Another interesting fact, new to me, is that the thrusters may actually fire after parachute deploy, to dampen any unwanted rotation of the capsule under the chute. That's never been done before. "Wrist mode damping is active throughout parachute descent and ensures a safe heatshield separation, good TDS surface acquisition, and a safe backshell separation" (p. 8).

Posted by: brellis Jun 28 2012, 01:25 AM

A question I had for Emily's *very entertaining and fear-reducing* Google-hang, still can't find an answer: how much more than .75m/sec vertical drop can the rover take, for example if the crane lets go too soon? Can it take the drop the Vikings withstood?

Edit: pospa's http://www.unmannedspaceflight.com/index.php?s=&showtopic=7138&view=findpost&p=185002 in the Cruise thread provides the basis for my question.

Posted by: PDP8E Jun 28 2012, 02:28 AM

I assume the cruise stages 'burn-up' (no heat shield).
Is there any evidence that there are pieces laying about in 'new craters' beyond or before the landing ellipses?
(i.e. Pathfinder, MER-A/B, Phoenix, others, and now MSL)

Posted by: djellison Jun 28 2012, 05:21 AM

I've had a look downrange for Opportunity in whatever MOC and HiRISE images I could - but found nothing.

Most would burn up - a few small components might make it thru - but I doubt a thorough analysis has been done.

As for touchdown rates - this is interesting reading
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/39907/1/06-1785.pdf

Posted by: brellis Jun 28 2012, 12:25 PM

Thanks Doug. So, on flat terrain, MSL can handle as much as 1.25m/sec vertical velocity whereas the Vikings landed at 2.5m/sec. I'm not nervous -- I'm perfectly calm!

Posted by: djellison Jun 28 2012, 02:11 PM

And we have 30+ years of improvements in radar, IMU's, software etc etc.

Moreover - it's not like 1.26m/sec will result in complete and utter devastation - a dinged wheel, a slightly bent suspension strut etc etc - the rover would still be able to carry on.

I'l wager the actual touchdown vertical velocity will be < 0.8m/sec

Posted by: ElkGroveDan Jun 28 2012, 04:51 PM

I'd also wager that those are spec tolerances. I'd be willing to bet it could take a bigger thump than that with no appreciable damage.

Posted by: MarsEngineer Jun 29 2012, 01:11 AM

Hi again,

Doug is correct (he seems to have the knack, me on the other hand...). There is margin well above 0.8 m/s (I forget the number but it depends a lot on surface characteristics if my memory serves). With these sorts of multi-DOF control systems, either it is coming down well within the spec or ... it won't and something is wildly wrong.

Ironically the Phoenix and Viking landers could not afford to land slower due to dynamics issues with slower velocity (need for leg stroke for touchdown detection, surface-plume interaction, fuel cost, etc). However the velocity knowledge and control accuracy for Viking and Phoenix was fantastic and about the same as MSL's (in fact MSL and Phoenix both use the same inertial measurement unit (IMU) design). Because of the skycrane architecture, MSL is simply able to capitalize on the IMU and on the fact that the decent engines are a long way from the surface and wheels, that the engines are dynamically uncoupled with the rover touchdown event to allow a much slower terminal descent velocity. If we were willing to use more fuel we could probably have reduced the velocity even more, but we did not need to. The big benefit of a slower touchdown is that the rover's wheels (aka "legs") can be used as landing gear plus that slow velocity really broadens the spectrum of Mars surfaces that are considered "safe". (Of course I am wildly biased - opinions expressed are those of the co-co-co-co-inventer and do not reflect NASA/JPL/Caltech).

With "somewhat controlled velocity" landing systems like MER (6 solid rockets) or "nearly controlled velocity" landing systems like Pathfinder (3 solid rockets) the landing system obviously has to be robust to a much wider range of impact velocities (let alone surface characteristics).

You know I can't tell you how much fun it is to come by here (I wish I had more time!!!). I get a huge kick from the thoughtful discussions of risk, and the fun walks through memory lane (like the link that SFJCody left on http://www.unmannedspaceflight.com/index.php?s=&showtopic=7138&view=findpost&p=185020 to a 1997 bulletin board about the weirdness of Pathfinder's landing system and even a discussion about my old web page on EDL I created back then - what a hoot!)

In my opinion, all of these missions (especially the ones that have to land safely on Mars) are experimental vehicles and have a rather substantial element of risk. For all of the Mars lander missions I have worked on (MPF, MER, PHX and MSL) like everyone else, I am initially daunted by the vast array of all the "things that must go right". The mountain ahead seems insurmountable. But then I (we) look down at my (our) feet and move myself one step at a time, one minute detail at a time, oftentimes with insufferable pauses as we ruminate, test and argue over the safety of each tiny step, sometimes having to go backwards and find another path or add new paths that we thought would never be there. Slowly, ever so slowly and with infinite patience we gain altitude, only vaguely aware of the progress we have made. The really hard part is knowing when the mountain has been scaled. Too often it appears that the summit is ahead and we can relax, only to discover that the top is further ahead than it appears, and yet another push must be mustered. Of course the top really can NOT be seen and no one knows for certain, until it is over.

I do find though that there is a feeling I get that tells me the top is there in front of me (if only I could see it). It is really a feeling that we have run out of places to put our feet. No more tests left to ponder, no more problem reports to close, no more reviews to hold, only a far away machine waiting for Mars to arrive. I think we have nearly run out of places to put our feet. Could it be that we are there? Almost, I see a couple of more places to step. Next couple of week perhaps?

-Rob Manning
MSL Chief Engineer and faux climber

Opinions expressed are indeed those of the author and do not reflect the opinion of NASA/JPL/Caltech

Posted by: nprev Jun 29 2012, 01:18 AM

Rob, and we are absolutely delighted when you do have a chance to visit, believe me!

Great post.

Posted by: Tesheiner Jun 29 2012, 06:43 AM

Posted by: Pertinax Jun 29 2012, 12:19 PM

Hi Rob,

Thank you for you post, particularly for your wonderfully visual description of methodically working through a seemingly impossible problem.

-- Pertinax

Posted by: Oersted Jun 29 2012, 02:33 PM

I wonder whether the planning and programming for non-nominal landing scenarios includes alternative thrusting profiles in case the bridles snag or are blocked as they spool out. Say, if the rover only descended half a meter on the bridle, would the descent stage then be able to recognise the situation and descend accordingly? It would of course mean a higher risk of plume damage, but better a dinged rover than no rover.

Posted by: MarsEngineer Jun 29 2012, 07:04 PM

Hi Oersted,

In our "stress and robustness" simulations (which we have been doing a lot of in the last few months), we try to think up cases like this to see where the system "breaks" using one of our software simulations (we have a couple of variants of simulation for different purposes - plus the testbed with all of the electronics in it too). We have tried cases like: slower (sticky) engine throttle responses, lower or asymmetric throttle engine performance, super slow bridle deployment. I don't think we tried the case where the bridle does not fully deploy (I will ask), but I am pretty sure it would work to a point - the architecture does not depend on the bridle length being "just right". The software doesn't "recognize the situation" per se, the software really does not monitor nor really care about the position nor orientation of the rover with respect to the descent stage, it simply waits for he ground to show up and "off load" the descent stage. The software "knows" that the rover is on the ground when it notices that the throttle settings have cut in half (as it must in order to maintain the descent rate of around 0.7 m/s even after the rover is on the ground - at least for a couple of seconds). And for that reason, a half meter bridle would mean that the descent stage would come down and make contact with the rover in those 2-ish seconds that it take for the software to notice that the rover has been off-loaded (remember there are uptake reels on both ends of the bridles to take up the slack). Plus there would be a lot more plume issues being that close to the ground.

I have personally witnessed the BUD (bridle/umbilical device) testing as well as the system level separation tests and I know the design pretty well. John, Tom and the gang put a lot of thought put into it as well as incorporating lessons from MPF and MER (which used centripetal friction brakes instead of an electro-magnetic brake). You might recall that on Spirit landing, the bridle's brake was a tad "too good" (too much friction) and the lander with Spirit inside took "much" (a few seconds) longer than we expected to deploy the bridle to full length (over the coming 3 weeks before Opportunity arrived, we frantically re-re-tested the brake in the expensive 25 ft space simulator). This new design avoids this possibility. It is a nice clean and elegant design they came up with. This does not keep me up at night.

If and when we find stress cases that do not work, we decide whether or not to do anything about them depending on our best judgement of the probability of occurrence vs level of difficulty in mitigating the threat. More often than not we find that that system muscles through the problem (for example a very short data outage on the bridle) , however when we consider "hard failures" (such as a failure to cut a bridle) we already know the outcome will not be good and we have known that from the beginning. In those cases we count on the reliability and simplicity of he design ... and of course we test it like crazy to "prove" it (we often misuse the word "proof" which implies deductive reasoning, rather we should say "demonstrate" for the inductive reasoning behind the bulk of our reliability arguments).

(I am really procrastinating today. I love to talk about this stuff.)

-Rob

Opinions expressed are those of the author and do not necessarily represent the views of JPL/Caltech/NASA.

Posted by: nprev Jun 29 2012, 09:54 PM

Rob, if you have the time & feel like it, I'd love to hear the history/thinking that led to the descent stage flyaway parameters.

When I first heard about it I figured the easy way would be to tilt it about 5 deg after bridle separation in any direction & let it rip full throttle until it smashed into something or ran out of fuel & crashed. Understand that the flight path is a bit more "elegant" now.

Posted by: Oersted Jun 30 2012, 01:21 AM

Rob, thanks for your informative and very interesting reply. We're fortunate to have caught you during those few extra moments when the preparations for the party are done, the rehearsals are all over, and the guests and relatives are just standing around, chomping peanuts and having a drink while awaiting the bridal, sorry, bridle arrival... ;-)

We know that you are of course actually very busy, but that just makes it an even bigger privilege to get these insights.

Posted by: DavidVicari Jun 30 2012, 01:48 AM

Rob,

Thanks for the great replies!!

You said the bridle doesn't keep you up at night... I have to ask, is there anything about the landing that is keeping you up??

From an outsider the thing that worries me the most is the parachute deployment. It seems like the least controllable and most chaotic of all the events. My second biggest concern is the number of pyros that must work. I know that they are extremely reliable but it still scares me a little.

Posted by: mchan Jun 30 2012, 06:22 AM

Another thanks to MarsEngineer. Your perspective on the engineering challenges give outsiders a view of the work on the inside, and are always informative and a pleasure to read.

Regarding the parachute, there is a great series of videos on the design and tests of the parachute and of the folks doing the design / test. You can see how early tests resulted in shredded chutes. One video featured a great practical joke where the data acquistion appeared to be bad in a full-scale wind tunnel test. This aspect of EDL appears to be well tested.

Posted by: Oersted Jun 30 2012, 10:20 AM

"JPLnews" Youtube channel:

Martian Series: Testing Curiosity's Parachute Part 1:
http://www.youtube.com/watch?v=O7vf2HUMMdo

Martian Series: Testing Curiosity's Parachute Part 2:
http://www.youtube.com/watch?v=JRRcbZlofOk

Martian Series: Testing Curiosity's Parachute Part 3:
http://www.youtube.com/watch?v=-NJamPhtRjA

Martian Series: Testing Curiosity's Parachute Part 3:
http://www.youtube.com/watch?v=J6TceTZq1L0

Posted by: claurel Jul 2 2012, 12:36 AM

I noticed that there's a relatively recent SPICE kernel available for MRO that covers the time window around MSL's entry, descent, and landing. I was curious what view MRO would have of Gale Crater, so I created a short visualization of the two spacecraft's trajectories near the time of the landing.

http://youtu.be/-f0BDnJNW-8

MRO's trajectory is plotted in a Mars-centered inertial frame, while MSL's is depicted in a Mars-fixed frame. Of course, the actual EDL trajectory of MSL is likely to vary somewhat from the predicted one in the SPICE kernel.

--Chris

Posted by: fredk Jul 2 2012, 04:54 PM

Sorry if this has been discussed, but I noticed Scott Maxwell say in a recent http://roadtoendeavour.wordpress.com/2012/07/02/three-thousand-sols/:

We've always referred to the MERs as "she's". Is the team referring to MSL as "he"? Oppy's younger (but bigger!) brother?

Posted by: elakdawalla Jul 2 2012, 05:08 PM

Scott insists that the rover is a "he" and affectionately calls him "George." I'm not sure of the origin of that name -- I'm sure he'd tell me if I asked him! -- but I always imagine the http://www.youtube.com/watch?v=2JlVqfC8-UI whenever I hear the name, which may itself be a reference to Of Mice and Men. (Of course the yeti's name wasn't George, that was the yeti's name for his pet bunny rabbit, but still...)

I, however, think Curiosity is a girl. So there.

I've heard "he," "she," and "it" from various people involved in the mission. Gender is, I guess, in the imagination of the speaker. You'll never see an official JPL press release refer to the rover as anything but "it."

Posted by: stevesliva Jul 2 2012, 05:21 PM

^ Curious George

Posted by: djellison Jul 2 2012, 05:36 PM

I call the testbed rover George - but I'm still getting used to Curiosity for the rover - and vessels of exploration are always she's - that's something Scott and I just have to disagree on

Posted by: RoverDriver Jul 2 2012, 05:55 PM

Since curiosity in italian is LA curiosita' (femminine), MSL is definitely a she.

Posted by: climber Jul 2 2012, 07:40 PM

Works the same way in French...

Posted by: pospa Jul 3 2012, 07:06 AM

As well as in Czech & Slovak.
But in Russian its "it", I gues .

Posted by: CryptoEngineer Jul 6 2012, 04:50 AM

We're invading Mars with a one-ton atomic robot, armed with a laser capable of vaporizing solid rock. Phobos-Grunt was a misdirection ploy.

Sounds like a male to me

pt

Posted by: SteveM Jul 6 2012, 05:06 PM

Since English has almost no gendered nouns and Curiosity's drivers are in the county of Los Angeles, it seems that the Spanish gender of la curiosidad (feminine) should govern here.

Steve M

Posted by: ElkGroveDan Jul 6 2012, 10:00 PM

It may be a bit arcane, but in one of the Looney Tunes Marvin Martian cartoons, Marvin takes Bugs Bunny to Mars as a pet for "Hugo" the Abominable Snowman (from a previous Bugs Bunny episode) that Marvin has captured and brought to Mars. Hugo grabs Bugs and declares, "I will hug him, and stroke him, and sing to him, and cuddle him, and call him George," Bugs then tells Hugo he doesn't want a rabbit, he wants a robot and tells him, " 'George' is a perfect name for a robot."

So there you have it. According to Bugs Bunny the perfect name for a robot on Mars is "George."

http://www.youtube.com/watch?feature=player_detailpage&v=7A4HeawmE6A#t=377s

Posted by: brellis Jul 7 2012, 12:01 AM

The third chapter of Emily's excellent series of blog entries about EDL mentions "landing gear", with an image of Curiosity prior to "landing gear" release. Does ~he~ have shock absorbers? I know, I'm worrying too much! hehee

I'm going to the Planetfest thingie in Pasadena, bringing a BIG bag of pistachios!

Posted by: Oersted Jul 8 2012, 05:14 AM

Just the suspension inherent in the rocker-bogie wheel configuration. It deploys from a folded-up state, but I am actually at a miss as to how it deploys. Just gravity drop? My guess is that there are some springs that are released with pyro firngs on deploy and which then serve as suspension afterwards.

Posted by: RoverDriver Jul 8 2012, 05:25 AM

Yep, the suspension system is released with springs/pyros. The "spokes" on MSL wheels also can take quite a beating. The tread also is compliant.

Paolo

Posted by: brellis Jul 8 2012, 08:47 PM

Reading this http://www.marsdaily.com/reports/Lifes_molecules_could_lie_within_reach_of_Mars_Curiosity_rover_999.html about MSL and "fresh craters", I wonder if consideration was given to aiming the descent stage and creating a brand new crater nearby?

Posted by: nprev Jul 8 2012, 09:13 PM

I think that the overriding concern is still residual hazmat for the descent stage; Curiosity's almost certainly never gonna go anywhere near the wreckage for that reason. Plus, I very much doubt that it'll hit hard enough to make a crater deep enough to excavate anything interesting from an orbital view.

Heck, come to that wouldn't be too surprised if it survives the crash in fairly good condition. The big variable is probably how much residual fuel (and therefore added velocity) it can burn off before it hits the dirt.

Posted by: RoverDriver Jul 8 2012, 10:26 PM

I haven't heard anything about observing the descent stage. I think you are probably right, the lesson from Oppy observing the heat shield will be influencing decisions in that regard. It wouldn't surprise me if they would use the mastcam to take a few pictures tho.

Paolo

Posted by: charborob Jul 9 2012, 01:38 AM

According to Emily's http://www.planetary.org/blogs/emily-lakdawalla/2012/07060700-how-curiosity-land-part-3.html about MSL's landing, the original plan was to burn off all the remaining fuel in the descent stage, but she says it will now burn for a fixed time (she doesn't say how long) and crash at least 150 m away.

Posted by: Explorer1 Jul 9 2012, 06:21 AM

Spirit's trenches were that deep at least.
Speaking of which, can MSL do the same thing with its wheels?

Posted by: centsworth_II Jul 9 2012, 06:56 AM

There was a reason to examine MER's heat shield that does not apply to the MSL descent stage. To see how well the materials weathered atmospheric entry. I wonder how far MSL's heat shield is likely to be from the rover after it lands.

Posted by: djellison Jul 9 2012, 03:27 PM

There will already be craters made by the heatshield, and the ballast masses ejected just before parachute deployment - they'll all be worth looking at and would, I'd have thought, be downrange ( east ) of the landing site by a km or 2.

The descent stage can't be aimed specifcially. It takes 4 engines to 100% and flies away at 45 degrees for 4 seconds of thrust and then falls ballistically, probably landing a very long way away. This was discussed, in length, in another MSL thread. Because it contains much organic chemistry and could potentially be and explosion risk - they will not be driving towards it for close study.

Posted by: Phil Stooke Jul 9 2012, 03:37 PM

And we'll see it with HiRISE. Points on a map!

Phil

Posted by: djellison Jul 9 2012, 04:20 PM

HiRISE will have...

Rover
Crashed Descent Stage
Backshell & Chute
Heatshield impact and debris
6 ballast mass impacts.

...to look at. It's going to be amazing

Posted by: B Bernatchez Jul 9 2012, 05:05 PM

I wonder if the first two ballast masses wouldn't burn up in Mars' atmosphere? Is there any expectation that they would survive enough to impact the surface? And if they did, would it be large enough for HiRISE to detect?

Posted by: climber Jul 9 2012, 07:38 PM

Would be fun to look for the ballast. Total weight of the 6 is 125kg ... to be compared to Oppy's 185 kg.

Posted by: Oersted Jul 9 2012, 08:03 PM

"Carpet bombing" comes to mind...

And yes, Explorer1, MSL will definitely be able to excavate some monster trenches by dragging its wheels. I am certain that this essential capability, the supreme serendipitous discovery of the MER missions, will be brought to bear in Gale Crater.

Posted by: Explorer1 Jul 9 2012, 08:54 PM

That's welcome news; no need for a heavy shovel on an arm.
Necessity is the mother of invention as we saw with both MERS, eh?

Posted by: walfy Jul 10 2012, 03:29 AM

There was some discussion a week or two ago about whether the lander, or sky crane, could still successfully deposit the rover on the surface in the event the tethers did not fully deploy. I was wondering what the experts thought about another scenario, albeit extremely unlikely. Let's say the rover landed safely, but a tether did not disconnect or it got hung up. Could one of the science instruments sever the cable?

Posted by: djellison Jul 10 2012, 06:06 AM

Remember - the descent stage doesn't land with the rover - it's coming down at 0.75m/sec and when the rover hits the deck it sees that off-loading as a drop in throttle level. It then cuts the cables, throttles up and flys away.

A cables-don't-cut scenario? The descent stage would, after commanding the cable cuts - work under the assumption they had cut - throttle up, pitch over 45 degrees and be out of there. I presume it would drag the rover with it and we would have a bad day.

I can't imagine a scenario where the descent stage is somehow still attached, but we have a healthy rover on the deck. If that situation were to occur (and I don't think it's actually possible) I don't think the drill or DRT could do much regarding the three ropes and the data cable. Imagine trying to cut a rope with a slow power drill. It would be near impossible on this planet - let alone on another, robotically. Plus - I'm not sure the arm could actually reach all four connection points. And - if the tethers are still on the deck in some way, trapped by the descent stage - then you couldn't deploy the mast to map the scenario and plan to use the robotic arm.

In short - a failure case I don't even think is possible, and I don't see a way out of it.

I could list probably a thousand tiny things that could go not-quite-right and cause a bad day on Mars. EDL is much like a rocket launch. When a rocket takes off, one of a thousand things could occur...and only ONE of them is good.

Posted by: Paolo Jul 10 2012, 07:54 AM

from experience in aerospace structures, I assumed the system had what is called a "weak link" that is designed to break in case something goes wrong like this.
for example, in flight refueling probes are designed to break in case the aircraft is unable to disconnect

Posted by: pospa Jul 10 2012, 03:45 PM

Could LIBS laser on ChemCam overburn those ropes if mast can be deployed?

Posted by: djellison Jul 10 2012, 03:59 PM

As I said - the mast would still be stowed, thus ChemCam would be hard bolted to the rover deck.

Posted by: walfy Jul 11 2012, 04:29 AM

Thanks for the informative replies. I won't get into anymore "what ifs." The moment of truth draws near. Time for positive thoughts!

Posted by: nprev Jul 11 2012, 05:32 AM

Noticed this article on the http://www.nytimes.com/2012/07/11/science/space/seven-minutes-of-terror-video-grabs-online-audience-for-nasa.html today re Curiosity's descent sim video...quite a successful public outreach effort, it seems.

VERY well done to all involved, esp. including Doug!

Posted by: djellison Jul 11 2012, 05:49 AM

About a year ago, a bunch of us were swapping you-tube-doubler links that tied the MSL animation to different sound tracks. My colleague Jon ( lead dev for Eyes on the Solar System ) found the inception soundtrack worked perfectly. EPO folk couldn't use it, obviously, but they were certainly inspired by it.

An awesome piece of work by the editing folk.

Posted by: climber Jul 11 2012, 05:53 AM

Mars is now visible from Curiosity as a 3'arc disk ~8 Million kms away

Posted by: Oersted Jul 12 2012, 01:36 PM

Odyssey in safe mode again, acc. to Paolo (JPL rover driver) in the Opportunity forum...

Posted by: climber Jul 16 2012, 05:18 AM

Pre_landing telecon tonight at 10AM Pacific: http://www.nasa.gov/home/hqnews/2012/jul/HQ_M12-128_Curiosity_Prelanding.html
I'm feeling like I'm back to december 2003 for Spirit's prelanding telecom
We're getting close

Posted by: jmknapp Jul 16 2012, 02:05 PM

Here's the Spirit pre-landing press conference, held on the day of the landing:

http://www.c-spanvideo.org/program/179768-1

Posted by: ElkGroveDan Jul 16 2012, 03:11 PM

Don't do that to me before I have had my morning coffee.

Posted by: akuo Jul 16 2012, 07:32 PM

Missed the press conf live, but its already visible as a recording here: http://www.ustream.tv/nasajpl

Watching the recording at the moment, but I find something strange in the released information and images. The press kit specifies the landing ellipse as 20x25km, and I remember the graphics before having a lot more circular ellipse. Now, looking at the press kit and some released images, I again see a quite elongated ellipse:
http://www.nasa.gov/mission_pages/msl/multimedia/pia15690.html

There are no scale there, so its difficult to understand the scale of the ellipse. Anyway, has the predicted ellipse become more elongated, and if so, is it more or less accurate than before?

Posted by: RoverDriver Jul 16 2012, 07:40 PM

20x25 Km is the nominal size for the ellipse. I don't have the most recent values but I believe it is in the 21x7Km range. I will find out and edit this post.

Paolo

Posted by: Phil Stooke Jul 16 2012, 07:42 PM

The ellipse was reduced in size a few weeks ago:

http://mars.jpl.nasa.gov/msl/multimedia/images/?ImageID=3855

Phil

Posted by: akuo Jul 16 2012, 07:51 PM

Ok, I haven't followed the official MSL site keenly enough:)

7km wide ellipse, that is really excellent.

Posted by: jmknapp Jul 16 2012, 08:15 PM

Thanks for the link--missed it too.

Posted by: djellison Jul 16 2012, 10:23 PM

21 x 7km is the size I used for the artwork

Posted by: jmknapp Jul 17 2012, 12:40 AM

An important item from the press conference was that due to a malfunction on Odyssey, the first indication of a successful landing might not be until several hours after the landing. Odyssey would have been positioned to receive UHF transmissions from MSL and relay them immediately ("bent pipe" telemetry) , but if Odyssey can't be positioned as desired due to the reaction wheel problem, then MRO will store and forward the data 3-4 hours later. Mars Express will be below the horizon at landing, as will Earth. Odyssey could contact MSL on its next orbit about 1-2 hours after landing.

Posted by: stewjack Jul 17 2012, 01:42 AM

That is the way I understood it from the press conference, however a BBC article suggests something different.
---
http://www.bbc.co.uk/news/science-environment-18861463
By Jonathan Amos Science correspondent, BBC News

As things stand, Nasa could be waiting on Odyssey to make a late pass of the landing site, perhaps five to 10 minutes after the rover's planned touch down.

This (MSL Landing) is projected to be 22:31 PDT 5 August; .....snip...
"If Odyssey is not able to be moved and it still remains late, that means it will fly over [Curiosity] after the spacecraft has landed, and we presumably will [then] be able to see transmissions from it. It would be somewhere between 22:35 and 22:40 PDT," explained Pete Theisinger, the rover project manager at Nasa's Jet Propulsion Laboratory in Pasadena, California.
---
Personally, I (in the CDT time zone) think I should plan for an all-niter.

Jack

Posted by: brellis Jul 17 2012, 03:11 AM

Dang it, I'm already half way through the first of the three bags of pistachios I bought for the PlanetFest thingy. Good thing there's a Trader Joe's on the way!

Posted by: nprev Jul 17 2012, 03:17 AM

Just for clarity's sake, we're talking about delayed return of the full EDL data set as the worst-case scenario in this situation, correct?

Would hate to lose any of that; you only get one shot per landing to get it, and it's invariably quite valuable for future mission planning.

Posted by: djellison Jul 17 2012, 03:38 AM

The baseline plan was...

X-Band DTE
Tones up until just after 'chute deployment in the MER stule

UHF
Bent pipe relay 8kps via Mars Odyssey
Store and Forward from Entry to Landing 8kbps via MRO ( that we would get at about landing +4 to 5hrs or so )
And partial carrier only via MEX

Now - the only change is the bent pipe 'live' 8kbps telem via MODY is in jeopardy.

I bet they'll find the time between now and landing to re-tweak MODY's orbit, burn a bit of prop, and get it back in place for bent-pipe relay. There's several decades of prop margin onboard.

Posted by: Syrinx Jul 17 2012, 03:42 AM

Not sure what you mean by "full data set" but Theisinger said the EDL pics would be stored and beamed back to Earth from the ground up, meaning LIFO style. The first EDL pics beamed back will be the ones taken closest to the ground and it would take 2-3 days to get all the pics.

Posted by: djellison Jul 17 2012, 03:49 AM

Oh - the MARDI dataset is 1600 x 1200 x approx 500 images and will take several weeks to download in full. A thumbnail preview and a few full resolution frames will be available in a couple of sols - but it'll take several weeks. Pete certainly didn't say it would be take 2-3 days to get 'all the pics'

What nprev is talking about is the live 8kbps telemetry that Odyssey was to bent-pipe relay straight to the ground. If ODY is not in place, this will now not be on the ground until MRO dumps it, which will take about 4-5 hours. it wont be lost, we'll just get it later.

We'll also probably have an MODY pass at L+2hrs or so anyway.

Posted by: Lightning Jul 17 2012, 06:14 AM

This means in case ODY can not be present at the right time, there is no backup to support MRO to get the data ?
And it then should be impossible to know what has happenned during EDL until 4 hours after landing ?

Posted by: djellison Jul 17 2012, 07:42 AM

There would be DTE tones until the Earth sets ( after chute deploy ) and MRO relay later. That would be it.

We would probably see an ODY pass at landing +2hrs that would tell us everything is fine. Infact, we'd get that data back before the 8kbps data transmitted during EDL.

Posted by: SFJCody Jul 17 2012, 07:48 AM

Awesome to know, thanks! I just recently noticed that someone has uploaded CNN's coverage of the Pathfinder landing to youtube.

http://www.youtube.com/watch?v=zUaalbRC7KA

http://www.youtube.com/watch?v=7Au-S-tjyiU

Posted by: MarsEngineer Jul 17 2012, 11:05 PM

Thank you SFJCody! You made my day. I had never seen the CNN coverage of Pathfinder coverage - at least if I did, I do not recall seeing it. (Yikes! I sounded like a DJ! But I am relieved to see that I have not aged a day! Not). There were moments that I had long forgotten. Those were happy moments. With a little luck we will have another one of those highly addicting moments.


I just spent the bulk of the day discussing MSL contingency procedures we have been developing for what we would do if we lost the signal(s) during EDL and immediately thereafter (of course we are considering ODY's targeting situation that Pete talked about - but I am not concerned by it). We have generic contingencies for the rover, but we needed a special one for the EDL - Sol 0 day. There are a lot of nerve-wracking ways for the signals to cease flowing and yet still allow us to recover the rover later on. So spent half the day reviewing and refining the plan.

It is amazing how much time we spend on the "negative" (i.e. things that can go wrong). It can easily get us down, but we have to do this in order to find and "mitigate" all of the risks that we face. We do this so that we can get that rush when everything works right and pages of new science text books flow down to us. Years of work trying to find all of the ways it won't work only to have what works left over.

-Rob

Comments are those of the author and do not represent the views of NASA/JPL/Caltech.

Posted by: jmknapp Jul 17 2012, 11:55 PM

I watched that too--it was hard to miss your smile after talking about all the pyrotechnics that went off on the 4th of July:



It was an amazing thing--if I recall correctly I was at someone's house for a party and the TV was on around midnight or the wee hours (ET), showing (practically) live pictures from Mars--mindblowing.

Posted by: atomoid Jul 18 2012, 02:00 AM

...but it sounds like MSL has to transmit after touchdown in order to send its EDL after ODY comes into view, so i'll have to keep chewing my fingernails over worst case scenario being EDL failure and total loss of data with no chance to analyze and learn... so after fingernails gone, proceed to toenails.. no?

Posted by: brellis Jul 18 2012, 05:25 AM

Wouldn't some limited direct transmit get recorded from Earth?

Posted by: djellison Jul 18 2012, 05:37 AM

No. MRO will still be in place to listen to and record all of the realtime EDL telemetry that Odyssey would have been relaying in realtime. If Odyssey is not there, we will still get everything MSL will transmit - simply delayed by a few hours as MRO downlinks and the ground team process and decode that recording.



As the press kit describes, there are direct to earth X-band tones, just like Pathfinder and MER. However - the Earth sets behind the vehicle somewhere between chute deployment and heatshield deployment, so they will be lost at that time.

Posted by: malgar Jul 18 2012, 06:42 AM

How is the planned sequence of X-band tones?

The first one is after parachute deployment, and then? Is it a continuos stream of tones or just "bips" after every important step of the landing?
Btw, my personal Human-band tones would be the cheers from mission control room Which steps of the landing do you think will be celebrated?

Posted by: Astro0 Jul 18 2012, 06:59 AM

There are tones from Cruise stage sep all the way through each phase of EDL.

I certainly recommend that everyone take time to read back through this and all the other relevant MSL threads.
A lot of what is being asked is already answered there.

There's also answers to be found by Googling the question or checking the http://mars.jpl.nasa.gov/msl/news/pdfs/MSLLanding.pdf.

Posted by: climber Jul 19 2012, 01:24 PM

As I red somewhere, if ODY isn't in the right position, the "7 minutes or Terror" will last much longer

Posted by: MahFL Jul 19 2012, 01:38 PM

There seems to be a glaring error in the press kit, it refers to a post launch briefing, after the landing.

Posted by: Explorer1 Jul 19 2012, 04:04 PM

Well, technically it is 'post-launch', right, so not really a typo?

Posted by: SpaceListener Jul 19 2012, 11:06 PM

I would like to know what are the X-Band tones and its meanings?

I suspected that the tones would say every important milestone saying Ok or bad with tone alike to Moorse Code. Isn't it?

The milestones would be:

1. Separating from the cruise spaceship
2. Deploy the parachute
3. Releasing the backshield
4. Releasing the parachute
5. Releasing the heatshield
6. Starting the landing propulsion
7. Distance from the surface
8. Hovering on the surface
9. Releasing the Curiosity
10. Separating Rover
11. Notification of Curiosity : Rover touchdown
12. Flying away of sky crane
13. Crashing of sky crane

End of 7 minutes of terror!

Posted by: SteveM Jul 19 2012, 11:36 PM

So would I; all I could find from searching the web is this passage on pp. 99-100 of http://descanso.jpl.nasa.gov/DPSummary/Descanso14_MSL_Telecom.pdf:

"Each timeline segment of EDL has its unique event schedule (parachute deployment, for example), and each segment will have a unique set of nominal and off nominal tones. The collection of tones, of which 256 are available, constitutes the MFSK dictionary."

Further search for an MSFK dictionary publicly available from NASA drew a blank. Is there a listing of the major nominal and off nominal tones?

Steve M

Posted by: djellison Jul 19 2012, 11:42 PM

I've not seen one publicly available.

Posted by: RoverDriver Jul 20 2012, 01:26 AM

The first pdf file I see by searching "descanso jpl msl telecom" is the most detailed document I could find.

Paolo

Posted by: Astro0 Jul 20 2012, 06:36 AM

Thanks Paolo. This is an excellent 5.46mb pdf http://descanso.jpl.nasa.gov/DPSummary/Descanso14_MSL_Telecom.pdf. Recommended reading to all.

Posted by: Tom Tamlyn Jul 21 2012, 02:08 AM

Pistachios rather than peanuts? Is this something new?

TTT

Posted by: RoverDriver Jul 21 2012, 02:22 AM

Peanuts = Standard Def
Pistachios = High Def

Paolo

Posted by: Tom Tamlyn Jul 21 2012, 06:17 AM

Posted by: djellison Jul 21 2012, 06:44 AM

There will be no tone for that. Once the descent stage ( and the hardware is descent stage - the maneuver is 'sky crane' ) begins it's fly-away, it is silent. There could be no descent-stage impact tone.

Moreover - as has been mentioned in this thread, and on the landing press kit - the Earth sets behind the vehicle shortly after parachute deployment - so all the likely tones thereafter will not be heard - they're academic.

Posted by: climber Jul 23 2012, 08:04 AM

As we'll loose direct contact during parachutte phase, this means Earth set in Gale about this time so, Earth will rise roughtly another 12 hours+ after landing. So, we'll recover direct contact with Curiosity on August 6th at about 11 am PST or 18 UTC but it'll be still night time at Gale so I wonder if they'll wait till Sun rise.

Edited: from MSL Landing kit: "early relays makes about 15 hours after landing" but I understand it'll be from an Orbiter. Anyway, as the HGA will be deployed on a later sol, I guess we "could" talk to Curiosity using the RLGA...which goes back to my question whether or not we'll attempt to communicate after Earth rise (if of any interest).

Posted by: dmg Jul 25 2012, 12:27 AM

Press release just out says Mars Odyssey orbit adjusted to allow bent-pipe data relay for MSL landing as planned.

Yay!!

See: http://www.bizjournals.com/sanfrancisco/prnewswire/press_releases/California/2012/07/24/DC45916

Posted by: Hungry4info Jul 28 2012, 05:00 PM

How much confidence is there in this site's ability to handle the traffic that it will experience on the EDL date? I know UMSF weathered past events pretty well. Is this expected to be no different?

Posted by: Stu Jul 28 2012, 05:23 PM

Yes.

Posted by: MahFL Jul 30 2012, 10:57 AM

MSL course fine tuned Sat night.

http://www.nasa.gov/mission_pages/msl/index.html

Posted by: pospa Jul 30 2012, 11:37 AM

It's interesting to compare all four TCMs:
(please correct me in case of wrong numbers)

11.1.2012 : TCM-1 - 59 min burn(s) -> dv = 5,5 m/s
26.3.2012 : TCM-2 - 9 min burn(s) -> dv = 0,78 m/s
26.6.2012 : TCM-3 - 40 s burn(s) -> dv = 0,05 m/s
29.7.2012 : TCM-4 - 6 s burn(s) -> dv = 0,01 m/s

All done by 8 Aerojet http://www.astronautix.com/graphics/m/mr111c.jpg (1 lbf each)

Posted by: DEChengst Jul 30 2012, 03:22 PM

Tonight on BBC Two at 21:00 BST:

Horizon "Mission to Mars" http://www.bbc.co.uk/programmes/b01llnb2

Posted by: nprev Jul 31 2012, 01:02 PM

Are we there yet?

Yes, in fact, we almost are!

Time to redirect to the http://www.unmannedspaceflight.com/index.php?showtopic=7388 thread!

GO CURIOSITY!!!

Posted by: pospa Aug 5 2012, 09:19 PM

Curiosity is less then 9 hours from landing.

MSL homepage:
"Controllers decided Sunday morning to forgo the sixth and last opportunity on the mission calendar for a course-correction maneuver.
The spacecraft is headed for its target entry point at the top of Mars' atmosphere precisely enough without that maneuver."

...
I guess this thread can be closed now.