mars_armer
Jul 16 2005, 12:07 AM
Be careful drawing conclusions from the MER landings. The lateral descent velocity was due to steady prevailing winds, and the change in direction occurred during RAD firing due to pendulum motion of the backshell/bridle. Neither of these will be a concern for Skycrane, because of the active control system starting at 1 km. There is plenty of control authority to null out the lateral velocity and develop a smooth, purely vertical descent, even under the influence of winds, since there is no parachute dragging the system around at that time.
The JPL engineers working on Skycrane are many of the same people who were responsible for implementing the Pathfinder/MER EDL system. Believe me, they are ecstatic about Skycrane (though of course it still has to be tested and proven). It promises to be a much more robust system, and much less susceptible to uncertainties about the Martian environment.
One non-obvious benefit of the tethered set-down is that it is very stable (i.e., zero rebound). On an uneven ground surface, one wheel will touch down and that corner's bridle goes slack, while the other corners are still taut (and still removing energy from the rover impact). The bridles aren't cut until the rover is firmly on the ground.
Also, the mobility system is already designed to survive driving off of rocks, so it doesn't need any (or at least not much) enhancement to survive the touchdown.
RNeuhaus
Jul 16 2005, 01:56 AM
QUOTE (mars_armer @ Jul 15 2005, 07:07 PM)
Be careful drawing conclusions from the MER landings. ...
Mars_Armer
Thank you much to let us know about your good note. I love to know on how these problems will be solved. I didn't account about the promiment wind direction for the landing process.
How far and how long time can Skycrane fly during its searching for the best place to land the MSL Rover? Will Skycrane start to fly at 1 km above of the surface? What is RAD?
Rodolfo
Gsnorgathon
Jul 16 2005, 07:50 AM
RAD = rocket-assisted deceleration. Those are the rockets in the backshell that fire from ~120m to ~12m above ground level, to slow the lander's decent velocity to ~zero when the bridle connecting the lander to the backshell/parachute is cut. As opposed to (or orthagonal to...) TIRS - transverse impulse rocket system, which is intended to cut the lander's horizontal velocity to zero.
Mars Exploration Rovers Entry, Descent, and Landing Trajectory Analysis has lots of details (except the expansion of the acronym 'TIRS', oddly enough).
djellison
Jul 16 2005, 08:21 AM
Transverse Impulse Rocket System ( I think?)
and DIMES was Descent Imaging Motion Estimation System...
Ladies and Gentlemen - welcome to acronym heaven
Doug
lyford
Jul 16 2005, 06:53 PM
AH?
dvandorn
Jul 17 2005, 09:16 AM
And what does AH stand for? Altitude Horizon sensor?
-the other Doug
djellison
Jul 17 2005, 09:37 AM
AH...acronym heaven
Doug
dvandorn
Jul 18 2005, 10:13 AM
Ah - AH!
Makes perfect sense...
-the other Doug
ljk4-1
Sep 23 2006, 04:03 AM
When the Skycrane has completed its purpose of depositing MSL safely on the
Martian surface - where is it going to go? And what will happen to it?
djellison
Sep 23 2006, 07:35 AM
Basically the same as the MER/MPF backshell - it'll fly away and destroy itself. I think the trade was still under debate as to if the 'fly away' would be actively controlled onboard or if it would just seperate and throttle up until the fuel ran out, the statistics of the situation dictating that 'recontact' was very very unlikely.
Doug
MarsEngineer
Sep 25 2006, 01:09 AM
QUOTE (djellison @ Sep 23 2006, 12:35 AM)
Basically the same as the MER/MPF backshell - it'll fly away and destroy itself. I think the trade was still under debate as to if the 'fly away' would be actively controlled onboard or if it would just seperate and throttle up until the fuel ran out, the statistics of the situation dictating that 'recontact' was very very unlikely.
Doug
That's right Doug. You have done a wonderful job of explaining the skycrane concept, and yes we ARE excited about this new design.
(I have heard many a puzzled observer wonder why we are headed toward even more RubeGoldbergian designs. Rather than blame ever-cannonball polishing engineers like me, I would rather blame that frustrating Red planet that beckons us. Someday I will share the genesis of the Skycrane design concept - you might not be surprised that we conjured this - and other new designs in early 2000 in the wake of the MPL loss in late 1999.)
The latest baseline is that the Descent Stage will have a simple computer on it that will fly the descent stage away at either a fixed attitude or a profiled attitude until the descent stage has run out of fuel at which point it "lands" unceremoniously some 100's of meters away from the rover.
By the way, I have notcied that some folks get our terminology confused. We do not use the word "skycrane" to describe the descent stage. Instead we use the term "skycrane" for the landing maneuver ("skycrane maneuver") that the descent stage performs. These include rover separation and lowering the rover on the triple bridle at a fixed, slow vertical velocity until the rover wheels have off-loaded the weight of the rover under the bridle and the descent stage releases (cuts) the bridles and flys away (as you describe). The fly-away atttitude of the decent stage is such that the descent stage is assured not to re-contact the rover. (By the way, we may use an electric brake to slow the rover-descent stage separation rather then the centrifuge/drum brake design of MER and MPF.)
I see a lot of interesting comments in this thread from last year, too bad I was not a member then, I would have enjoyed clearing up a few questions.
-Rob
***********
Comments made here are the authors and do not represent the views of NASA, Caltech nor JPL.
chris
Sep 25 2006, 08:59 AM
QUOTE (MarsEngineer @ Sep 25 2006, 02:09 AM)
I see a lot of interesting comments in this thread from last year, too bad I was not a member then, I would have enjoyed clearing up a few questions.
Well if you find any that weren't answered, now's your chance
Chris
climber
Sep 25 2006, 11:01 AM
QUOTE (MarsEngineer @ Sep 25 2006, 03:09 AM)
Someday I will share the genesis of the Skycrane design concept - you might not be surprised that we conjured this - and other new designs in early 2000 in the wake of the MPL loss in late 1999.)
-Rob
And we, poor human, we thought that you just came back to Airbags system because you were sure it was working OK... I mean except yourself, Rob, since you nearly turned blue on Spirit landing day
By the way, I have notcied that some folks get our terminology confusedSo, in the terminology, "Skycrane maneuver" will be part of the EDL?
I love this place! Sometimes I feel I work for JPL.
djellison
Sep 25 2006, 11:09 AM
Skycrane is the manouver conducted by the decent stage to deploy the rover... I think that puts the three phrases into their proper context.
Doug
centsworth_II
Sep 25 2006, 03:13 PM
QUOTE (MarsEngineer @ Sep 24 2006, 09:09 PM)
By the way, I have notcied that some folks get our terminology confused. We do not use the word "skycrane" to describe the descent stage. Instead we use the term "skycrane" for the landing maneuver ("skycrane maneuver") that the descent stage performs.
In this case you might want to go with the flow and call the descent stage a skycrane. It's such a cool name for a levitating crane! I can see this piece of equipment developing a fan base which attributes a personality to it similar to what has happened with the MERs. Of course the MSL will be the real star but I think Skycrane will find a place in people's hearts. I can't imagine this happening with any previous decent system. Noone called the MER system Baggie, or the Phoenix system Footsie.
Jim from NSF.com
Sep 25 2006, 04:49 PM
Flow? This website does not determine the flow of the program, it is the workers.
centsworth_II
Sep 25 2006, 05:23 PM
QUOTE (Jim from NSF.com @ Sep 25 2006, 12:49 PM)
Flow? This website does not determine the flow of the program, it is the workers.
As Alan Stern pointed out in one of his first posts here: "PIs are people too." I assume that also goes for most of the others involved in a program. (My humble apologies to any computerized program members.) The workers in a program may determine its flow, but the seeds for ideas can come from anywhere.
MarsEngineer
Sep 28 2006, 06:26 AM
I dunno. Footsie and Baggie sound pretty good to me.
I suppose we could call the MSL descent stage the "skycrane", but that name is taken by Sikorsky and "skycranie" does not have a good ring. But hey, we are engineers, it has to have an acronym, right? And DS has only two letters.
(and yes, the skycrane maneuver IS part of EDL, with an emphasis on the L part)
We were inspired by the Skycrane (Sikorsky CH - 54B) helicopter's stability (we were shown a clip of huge construction equipment being precision-assembled by a Skycrane in a remote location in Canada). We even had a skycrane expert/pilot on one of our early review boards who attested to the stability of these systems (of course with a human crane-operator in-the-loop rather than guidance and control software).
When we first considered the skycrane lander architecture in Feb of 2000 (roughly - still a couple of months before we conjured MER), it was thought that it was too tough a control problem (need to damp complex pendulum modes). We actually discarded it then. Later, on MER, with the need to understand the dynamics of the RAD solid rockets and the TIRS (transverse rockets) attached to the backshell, we learned that MER dynamics was more than a bit like the skycrane concept. The key difference was that MER (& MPF) retained the parachute. That made the MER analysis problem much harder as calculating (modeling) the forces the parachute exerted on the backshell during a quick RAD deceleration is tougher than it looks. Without the parachute attached and a single bridle confluence point near the center of mass of the DS, the skycrane lander architecture is remarkably easier to understand and control (at least we think that after years of analysis and simulation).
We came away being more and more interested in the idea and by 2002, we were sold (while also being busy getting MER ready). It is not that we do not like airbags, it is simply we do not trust our ability to make them safely land big landers. Airbags will have a place in the future I think (as well as other architectures that some of you may think up - we are not too proud to borrow ideas from any and all sources - provided we do not infringe on anyone's copyrights).
Cheers,
-Rob
PS Amazing picts from of Duck Bay today, eh? The scale is hard to grasp. We are excited.
***********
Comments made here are the authors and do not represent the views of NASA, Caltech nor JPL.
chris
Sep 28 2006, 09:07 AM
QUOTE (MarsEngineer @ Sep 28 2006, 07:26 AM)
still a couple of months before we conjured MER
Now we know why they last so long. The secret ingredient is magic pixie dust..
Chris
lyford
Sep 28 2006, 03:58 PM
QUOTE (MarsEngineer @ Sep 27 2006, 11:26 PM)
I dunno. Footsie and Baggie sound pretty good to me.
I suppose we could call the MSL descent stage the "skycrane", but that name is taken by Sikorsky and "skycranie" does not have a good ring.
iCrane? skyPod? The Big Dropper? The thing that turned "6 minutes of terror" into "6 minutes and ten seconds of terror?"
Or else you could always use the term Skycrane with Sikorsky's blessing and corporate sponsorship.
But I believe true nicknames cannot usually be planned. They must evolve on their own...
centsworth_II
Sep 28 2006, 04:57 PM
An alternate delivery system: Skystork?
Click to view attachment
centsworth_II
Sep 28 2006, 05:01 PM
QUOTE (lyford @ Sep 28 2006, 11:58 AM)
But I believe true nicknames cannot usually be planned. They must evolve on their own...
They also do not respect copyright. I suspect that the MSL delivery system will end up being called, informally, Skycrane.
centsworth_II
Sep 28 2006, 05:10 PM
QUOTE (MarsEngineer @ Sep 28 2006, 02:26 AM)
When we first considered the skycrane lander architecture in Feb of 2000 ....
Thanks for the behind-the-scenes look. What a day that will be here at UMSF when it all unfolds on Mars!
climber
Apr 16 2007, 09:27 PM
May be not in the proper section but...
From AW&ST, I didn't know this :
...and plans to learn more about the Martian atmosphere from instruments to be placed on the heat shield that will protect the Mars Science Laboratory set for a 2009 launch.
Tom Tamlyn
May 5 2007, 08:30 PM
Good 4 minute
YouTube clip of Rob Manning at the May 2006 JPL open house discussing Mars exploration generally, and in particular the basis for JPL's decision that the skycrane was a better landing system for MSL than an airbag system. See also his
earlier post in this thread.
Manning as usual does a wonderful job of communicating the excitement and challenge of planetary exploration engineering. I wish he'd write a book.
TTT
djellison
May 5 2007, 08:42 PM
QUOTE (Tom Tamlyn @ May 5 2007, 09:30 PM)
I wish he'd write a book.
I bet he wishes he had the time to write it
From '92 to the day MSL lands, it would be one HELL of a story.
Doug
Jim from NSF.com
May 7 2007, 11:35 PM
QUOTE (centsworth_II @ Sep 28 2006, 01:01 PM)
They also do not respect copyright. I suspect that the MSL delivery system will end up being called, informally, Skycrane.
It isn't. It is called the lander
djellison
May 8 2007, 07:27 AM
There is no doubt in my opinion that the press will get the naming wrong and called the decent stage the 'skycrane' instead of a decent stage performing a skycrane manouvre.
centsworth_II
May 8 2007, 03:22 PM
With all due respect to Jim, it may formally be known as the lander, but
I predicted that it would
informally become known as the skycrane.
QUOTE (djellison @ May 8 2007, 03:27 AM)
There is no doubt in my opinion that the press will get the naming wrong...
Why fight it? What better to perform a "skycrane maneuver" than a Skycrane?
Anyone making a point of correcting the press on this will come off as an
out-of-touch nerd. And not an admirable, brainy nerd but an
inadmirable,
petty nerd.
Personalizing the *yawn* lander with a cool name that matches the inherent
coolness of its functionality would be a good PR move and eliminate all the
corrections that you point out will likely be necessary. Those corrections will
be an anchor in any interview on the subject.
centsworth_II
May 8 2007, 04:01 PM
QUOTE (Jim from NSF.com @ May 7 2007, 07:35 PM)
It is called the lander
I'm confused. Isn't it the decent stage that performs the sky crane maneuver
while the lander is the MSL itself?
And back to possible confusion in the press: How is one to tell whether
"Sky Crane landing maneuver" refers to a maneuver called "Sky Crane"
or a maneuver performed by some
thing called Sky Crane?
http://trs-new.jpl.nasa.gov/dspace/bitstre...8/1/05-3862.pdfIt would be terrible to have this confusion become the central point of
any live interview the press conducts on the MSL mission.
climber
May 9 2007, 09:19 AM
Put it this way : replace the words "airbags" or "retro-rockets" from previous mission (including phoenix) by "skycrane". It has to be THAT easy.
Jim from NSF.com
May 9 2007, 05:22 PM
Lander and descent stage have been used interchangability. Descent stage would be more appropriate.
Skycrane doesn't even need to go to the "outside" No need to say it. "The descent stage lowers the rover to the surface via three cables'
centsworth_II
May 9 2007, 11:54 PM
QUOTE (Jim from NSF.com @ May 9 2007, 01:22 PM)
Lander and descent stage have been used interchangability.
Descent stage would be more appropriate.
No kidding. Talk about confusing: A lander that doesn't land,
it crashes, by design. Athough it does
land the MSL.
QUOTE (Jim from NSF.com @ May 9 2007, 01:22 PM)
Skycrane doesn't even need to go to the "outside" No need to say it.
"The descent stage lowers the rover to the surface via three cables'
What a shame it would be to hide away such a cool term. But fear not,
the press will not allow it. Whether in correct context or not, I predict that
the term "skycrane" will be used over and over, ad nauseam. It's too
sexy to ignore. I only hope that every discussion involving the term does
not turn into a boring lecture on how, yes, the maneuver is called "skycrane",
but, no, there is no actual, physical skycrane as part of the mission.
mcaplinger
May 10 2007, 02:34 AM
QUOTE (centsworth_II @ May 8 2007, 08:22 AM)
With all due respect to Jim, it may formally be known as the lander, but
I predicted that it would informally become known as the skycrane.
For what it's worth, at MSSS none of us call it anything in particular; I don't even think we consider it a separate entity, it's just a subsystem.
centsworth_II
May 10 2007, 05:33 PM
I just think that this "revolutionary, new, sexy" landing system will be a natural
hook for the general press. I see it as the primary point of discussion in a lot
of stories and interviews before the landing. I don't think you will be able to get
away long with not calling it "anything in particular."
dvandorn
May 10 2007, 06:22 PM
Actually, my prediction is that the people who developed MSL's landing architecture will be standing in the control room on landing day, and the following thought will flit through their heads at some point or another:
"This is *crazy*!!! What the heck were we *thinking*?????"
I predict that this will happen regardless of the landing architecture selected...
-the other Doug
Jeff7
May 10 2007, 06:29 PM
QUOTE (centsworth_II @ May 8 2007, 12:01 PM)
And back to possible confusion in the press: How is one to tell whether
"Sky Crane landing maneuver" refers to a maneuver called "Sky Crane"
or a maneuver performed by some
thing called Sky Crane?
http://trs-new.jpl.nasa.gov/dspace/bitstre...8/1/05-3862.pdfThere's always the Picard Maneuver, named after Picard. The Star Trek community seems to have accepted this just fine.
The Skycrane Maneuver may be used in future missions, but there will only be one Skycrane.
To use Star Trek a bit more, first there was the Excelsior, then all that followed the design had different names, but were Excelsior-class ships. Future lander-delivery-systems of this sort could by Skycrane-class, but with other catchy names.
And what better way to pay respects to the S-64 Skycrane? It was a good technique for Earth, so now we're using it on
another planet.
centsworth_II
May 10 2007, 07:06 PM
QUOTE (Jeff7 @ May 10 2007, 02:29 PM)
The Skycrane Maneuver may be used in future missions, but there will only be one Skycrane....
And what better way to pay respects to the S-64 Skycrane? It was a good technique for Earth, so now we're using it on another planet.
Well, when you put it that way... it makes sense.
MarsEngineer
May 26 2007, 08:23 PM
Hi all,
Been a while since I posted last. (I noticed my friend Mark Adler has stopped by).
Just to be clear, at JPL we simply call the (big) thing that the rover hangs under as it touches down the "descent stage". We call the (sub) phase of EDL (entry descent and landing) that starts when the rover separates from the descent stage attached to three 7 m tethers (bridles) until the rover touches down the "skycrane phase" or the "skycrane maneuver". (I liked the Picard suggestion ....)
We started calling it that so that people could visualize the very precise "overhead crane"-like operations that the Skycrane helicopter folks so exquisitely use.
The word "lander" is rarely used by MSL. As you noticed that word really can only apply to the rover iteself. But "rover-lander" really does not roll off the tongue.
The MSL EDL gang just had their very important "critical design review" that included all aspects of the MSL EDL design. They did a great job ! (I am biased of course, they are my friends afterall).
I will try to pop by more often this (northern) summer. I have been very busy with Phoenix....
(almost ... there!)
-Rob Manning
********************************************************************************
Opinions expressed here are the author's and do not represent the views of NASA, JPL nor Caltech.
nprev
May 26 2007, 09:39 PM
Hey, Rob!
Thanks for the update; glad to hear it passed CDR.
Have to agree with US$0.02...the press is gonna go nuts over the skycrane, will add a lot of drama to the EDL sequence. (As a side note, somebody at JPL might want to make sure that Sikorsky is all right with this term; big companies like that can sometimes be extraordinarily jealous of trademarks, even though the S-64 has been out of production for quite some time...) Anyhow, main point here is that MSL's descent
will attract a great deal of press attention, so hopefully JPL's PR department will prepare accordingly.
MarsEngineer
May 27 2007, 12:45 AM
Hi nprev.
I am not 100% certain, but I think someone did check that the use of the name was ok. I will ask when I get a moment.
Certainly the MSL landing will get a lot of press time, but it will not be as dramatic as a 5 m wide, 500 kg airbag bouncing more than 12 m over your head.
The MSL team recently completed the construction of the "scare crow" rover. It is the first fully functional MSL mobility system that was built to test landing (on wheels) as well as general mobility (imagine MSL without the "body", just the wheels, motors and rocker bogie system.) It is rather versatile. They have even scaled rocks between 0.5 and 1 m without a problem. They also have been doing "landing" tests.
Because MSL's descent stage is more than 7 m above the rover, it can land slower than either Viking or Phoenix. MSL can land on its wheel at a very slow speed (limited only by the amount of fuel we feel we can use - the others need to keep the speed high so as to make good ground contact and to prevent tenching by the engines). MSL's wheels make contact at well less than 1 m/s whereas Viking & Phoenix had to land at 2.4 m/s (vertical). Of course MER was designed to land at more than 15 m/s. The upshot is that MSL's "landings" are rather anti-climatic.
But watching a car-sized rover scale rocks the size of chairs IS impressive.
-Rob
**********************
Opinions expressed here are the author's and do not represent the views of NASA, JPL nor Caltech.
nprev
May 27 2007, 01:28 AM
Cool, Rob; thanks so much for this detailed info!
I feel warmer & fuzzier...less than 1 m/s touchdown velocity, you say? I look forward to a truly brilliant anti-climax, then!
centsworth_II
May 27 2007, 02:50 AM
QUOTE (MarsEngineer @ May 26 2007, 08:45 PM)
Certainly the MSL landing will get a lot of press time, but it will not be as dramatic
as a 5 m wide, 500 kg airbag bouncing more than 12 m over your head.
MSL's landing will be PLENTY dramatic in it's own way. A car-sized
rover being lowered to the surface of Mars from a support structure
flying seven meters above has a very high cool factor.
lyford
May 27 2007, 06:25 AM
QUOTE (MarsEngineer @ May 26 2007, 05:45 PM)
I am not 100% certain, but I think someone did check that the use of the name was ok.
Rob - so good to see you posting here again!
I could be mistaken, but I think Erickson owns the Skycrane now - which they seem to call Aircrane...
http://www.ericksonaircrane.com/Of course, an aircrane maneuver doesn't sound as cool as a Skycrane Maneuver, 'specially at only 7-10 millibar.
centsworth_II
May 27 2007, 03:35 PM
MarsEngineer @ May 26 2007, 05:45 PM --
"I am not 100% certain, but I think someone did check that the use of the name was ok."
Quick, NASA or JPL, snap up the name "Marscrane"!
mchan
May 27 2007, 06:11 PM
QUOTE (MarsEngineer @ May 26 2007, 05:45 PM)
Certainly the MSL landing will get a lot of press time, but it will not be as dramatic as a 5 m wide, 500 kg airbag bouncing more than 12 m over your head.
The video of the simulated EDL makes it look quite dramatic, thank you. It will be another nail biter, at least for this layperson!
MarsEngineer
May 28 2007, 11:23 PM
Marscrane eh? not bad !
I have to agree that MSL's landing probably won't be dull. All of Mars landings seem to be nail biters, even at 1 m/s. (Did I mention that mine have grown back again?)
Like MER and Phoenix, we hope to get reasonable (at least 8 kbps) UHF data during the landing via one of the orbiters. Probably (like Phoenix and MER) we will not see that data in anywhere near real time. We will have to suffice with hi def animations and anxious faces. (Phoenix doesn't have a direct-to-earth X-band link after the cruise stage comes off, so data will all be returned via delayed UHF relay.) If something goes wrong during EDL for either mission we believe our "EDL com" designs will give us a huge hint at what went wrong. Despite the cost, complexity and even a small degree of added mission risk, the addition of EDL com has become all but mandatory.
Not knowing why your spacecraft disappears during landing is extraordinarily frustrating; my friends from Mars Polar Lander and Beagle II know the feeling far too well. I was watching through the MPL MSA (mission support area) window watching for the first signal from the surface from MPL in late '99 - one that never came. It was terrible. Although there are plenty of candidate causes (and at least one in particular), we have never discovered what really caused the loss of MPL. (We have learned even more about MPL from Phoenix.)
Now that the weather is warming up in the south and the CO2 frost is sublimating, we hope to get our first glimpse of the center of MPL's landing ellipse with HiRISE sometime in the coming months. But it is likely to be a bit of a needle in a haystack to actually see the lander or its jetsam. The landing ellipse is quite large compared with the HiRISE images.
It is worth taking a look. (Some interesting HiRISE science there too).
Take care,
Rob Manning
**********************
Opinions expressed here are the author's and do not represent the views of NASA, JPL nor Caltech.
mcaplinger
May 29 2007, 12:37 AM
QUOTE (MarsEngineer @ May 28 2007, 04:23 PM)
Like MER and Phoenix, we hope to get reasonable (at least 8 kbps) UHF data during the landing via one of the orbiters. Probably (like Phoenix and MER) we will not see that data in anywhere near real time.
For Spirit, you had UHF data from MGS before you had the post-landing tones. It's not my fault you didn't pay any attention to it.
MarsEngineer
May 29 2007, 10:33 PM
Indeed you are correct Mike!
We did not mentally "calibrate" how meaningful word of UHF data via MGS/MOC/MBR would be. In particular, some of us (me) thought that the data from MGS would lag by quite a bit, so when we heard that you and Mike were reporting UHF data from Spirit, we did not know if that meant post-landed data or (buffered) pre-landed data.
Ironically we also heard word on the voice net that the Stanford UHF antenna also reported seeing a signal after landing and before the post-landed tone via the lander's UHF antenna. Some of us (me) were so conditioned to think that they were going to see noise that we took it with a grain of salt.
Instead for about 17 minutes, as I stared at the absent X-band signal, I was locked in an entirely too negative mental zone wondering why I ever agreed to talk to Adler in April '00. (I thought that we lost the X-band way too soon at landing. I has having the same sickening feeling that I had had in the MPL MSA in Dec '99.)
I still find it nearly incredible that the first time that the MGS/MOC/MBR UHF was really used as intended, after years of being in space, was while it was listening to a vehicle it had never talked to before while that vehicle was suspended under a parachute falling toward Mars. Very very cool. You guys did a rocking good job. What a thrill!
This won't happen on PHX (Phoenix) however (I do not recall if we can use Stanford). We are using open-loop (canister) record mode in the UHF receivers on both ODY (Odyssey) and MRO. Some lag to get the recorded signal to the ground, bigger lag to get the data pulled out of the noise computationally. This makes for a more robust link, but adds time to get the signal into our hands.
-Rob Manning
**********************
Opinions expressed here are the author's and do not represent the views of NASA, JPL nor Caltech.
mcaplinger
May 30 2007, 02:57 AM
QUOTE (MarsEngineer @ May 29 2007, 03:33 PM)
We did not mentally "calibrate" how meaningful word of UHF data via MGS/MOC/MBR would be. In particular, some of us (me) thought that the data from MGS would lag by quite a bit, so when we heard that you and Mike were reporting UHF data from Spirit, we did not know if that meant post-landed data or (buffered) pre-landed data.
First off, about the "you and Mike were reporting". As I've pointed out before, that was Wayne Lee's misidentification, as Malin was at JPL, and not on the voice net. It was me, me, all me!
During the development of the relay capability for MER, we were always careful to not make any latency guarantees, since so much depended on circumstances beyond our control (bad DSN tracks requiring recorder playbacks, the need to tweak software if needed, etc, etc.) For EDL it all worked, and we leaned on our own processing pretty hard to get the data to JPL quickly, but I could understand if you didn't expect that.
QUOTE
I still find it nearly incredible that the first time that the MGS/MOC/MBR UHF was really used as intended, after years of being in space, was while it was listening to a vehicle it had never talked to before...
Thanks. A bunch of people at MSSS, CNES, Alcatel, and LMA worked really hard to make it happen. I'm just as glad the whole effort ended up as a footnote, since the only way it wouldn't have been was if a MER had crashed and been lost.
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