Author Topic: EEVblog #328 - Curiosity Mars Rover Landing  (Read 42245 times)

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Offline EEVblog

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EEVblog #328 - Curiosity Mars Rover Landing
« on: August 02, 2012, 11:53:39 am »


Dave.
 

Offline radioman.lt

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #1 on: August 02, 2012, 12:55:46 pm »
d{^__^}b - it's time to fly
 

Offline Electroalek

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #2 on: August 02, 2012, 03:11:54 pm »
Are these live streams worldwide ?

   › mars.jpl.nasa.gov
   › nasa.gov (NASA TV)
   › jpl.nasa.gov (Ustream)
   › Commentary/Conference Schedule
 

Offline Mr Smiley

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #3 on: August 02, 2012, 03:32:18 pm »
Hi All,

If Curiosity is running Windows There doomed.

All you'll see on the live feeds will be the BSOD or 'your computer will be rebooted in 15,14,13,12 ."  :-\

 ;)

Mr Smiley  :)
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Offline SeanB

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #4 on: August 02, 2012, 04:17:02 pm »
Somehow do not thing it runs windoze, more likely something more RTOS and a lot morre robust and able to detect and correct errors. Think BIG BLUE software, running on a space rated processor, and not likely a X86 based architecture.
 

Offline TerminalJack505

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #5 on: August 02, 2012, 04:38:14 pm »
I just hope the software engineers remembered to enable priority inheritance this time. 

In 1997 the Pathfinder, running VxWorks, shortly after landing, kept resetting itself.  It was eventually determined to be a priority inversion issue.  Lower priority threads would grab a mutex and starve-out higher priority threads when they blocked trying to acquire the same mutex.  A watchdog timer would notice that the higher priority thread wasn't running in a timely manner and reset the system.

Priority inheritance would have boosted the priority of the lower priority thread to that of the higher priority thread when the OS noticed the higher priority thread was waiting on the mutex being used by the lower priority thread. 

It's an interesting read if you're into embedded systems.
 

Offline lemming

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #6 on: August 02, 2012, 04:41:59 pm »
Computers: The two identical on-board rover computers, called "Rover Compute Element" (RCE), contain radiation-hardened memory to tolerate the extreme radiation from space and to safeguard against power-off cycles. Each computer's memory includes 256 KB of EEPROM, 256 MB of DRAM, and 2 GB of flash memory.[47] This compares to 3 MB of EEPROM, 128 MB of DRAM, and 256 MB of flash memory used in the Mars Exploration Rovers.[48]

The RCE computers use the RAD750 CPU, which is a successor to the RAD6000 CPU used in the Mars Exploration Rovers.[49][50] The RAD750 CPU is capable of up to 400 MIPS, while the RAD6000 CPU is capable of up to 35 MIPS.[51][52] Of the two on-board computers, one is configured as backup, and will take over in the event of problems with the main computer.[47]
The rover has an Inertial Measurement Unit (IMU) that provides 3-axis information on its position, which is used in rover navigation.[47] The rover's computers are constantly self-monitoring to keep the rover operational, such as by regulating the rover's temperature.[47] Activities such as taking pictures, driving, and operating the instruments are performed in a command sequence that is sent from the flight team to the rover. http://en.wikipedia.org/wiki/Curiosity_rover

Also http://en.wikipedia.org/wiki/Comparison_of_embedded_computer_systems_on_board_the_Mars_rovers is a good read.
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Offline PeteInTexas

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #7 on: August 03, 2012, 05:34:42 am »
I have no confidence in this sky crane thing.  Too many moving parts.

I find it hard to believe they could not solve the dust problem caused by the rockets.  Lens cover anyone?  ::)

I would have done either two parachutes- before and after the hovering rockets, or the airbag thing after hovering.
 

Offline MikeK

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #8 on: August 03, 2012, 02:02:09 pm »
Here's a cool solar system simulator: http://eyes.nasa.gov/index.html

You can view the MSL spacecraft in its current position, pick a time, or run through the EDL sequence (the preview mode).  As well as check out other spacecraft, planets, dwarf planets, and such.

I plan on being late for work on Monday.  Since I was at Cape Canaveral to watch the launch in November and have been anxious for August 5th to arrive.  Cool technology, I hope it all works.
 

Offline ProBang

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #9 on: August 03, 2012, 02:32:23 pm »
[...]
I would have done either two parachutes- before and after the hovering rockets, or the airbag thing after hovering.

With this rover? Sure.
But I think, this kind of landing is a early test for a human mission to mars.
At least two reasons:

1. It's a very smooth landing.
(After a couple of month at zero gravity the astronauts will be not the fittest.)

2. The landing area is visible.
(Very important, if you want to be sure, that the Habitat is landing on plain, safe ground.)
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Offline lewis

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #10 on: August 03, 2012, 04:27:00 pm »
If the dust from the descent rockets is a massive problem, which it sounds like it is because they've used the awesome sky-crane thing, why not put the rover in a bag? Descend all the way to the surface on rockets with the rover encased, then get the rover to cut its way out of the bag when all the dust has settled. Simples!

Come on NASA, where's your job application form?

Really REALLY looking forward to this, it will be an absolutely astonishing engineering achievement even if it doesn't work.
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Offline SeanB

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #11 on: August 03, 2012, 05:30:03 pm »
Remember this little rover is the size and mass of a Toyota Yaris.............
 

Offline laborratte

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #12 on: August 03, 2012, 06:07:29 pm »
Curiosity landed - somehow...
http://youtu.be/yjiGH9QNiU0
 

Offline jpelczar

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #13 on: August 03, 2012, 06:27:52 pm »
I wonder if it would be possible to create a network of space relays, deployed in various area of our solar system, which would amplify  the signal from the satellites, so we would get better data quality ? Or would it kill the entire NASA budget ? ;)
 

Offline SeanB

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #14 on: August 03, 2012, 06:52:18 pm »
Difficult to launch a 30m dish into space easily, as the power from the rover side is very limited. You also need a lot of power for the signals towards the probe, as again a sensitive receiver with a small antenna is limited because of space and power limits. NASA is doing well enough with what is left of the Deep Space Network dishes, even though most of them are relics from Apollo.
 

Offline Zad

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #15 on: August 03, 2012, 07:12:27 pm »
Better to have relatively small relay spacecraft in orbit around the planet where the rover is working. You can then install sensors on the relay and do additional science. You won't get 24/7 coverage but it works out pretty well on Mars now.

Incredibly, when one of the rovers had a firmware problem very early in the mission, they were able to talk to it directly via the short omni-directional vertical antenna.

Offline free_electron

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #16 on: August 03, 2012, 07:49:09 pm »
Hi All,

If Curiosity is running Windows There doomed.

All you'll see on the live feeds will be the BSOD or 'your computer will be rebooted in 15,14,13,12 ."  :-\

 ;)

Mr Smiley  :)
why is it that invariably some moron feels the need to bring something like this up ?

Serious embedded systems do not run Windows as a core os. Neither do they run botched-together and endlessly forked contraptions like linux.
Serious embedded operating systems are timing accurate , fully deterministic systems like VxWorks, pSos, Nucleus or iRMX and run on rugged, hardened hardware with erro correcting memory. It is extremely hard to make a system like iRMX go tits up... We have several pieces of equipment (Eaton Ion Implanters) that run this Os. I have seen catastrophical hardware failures that wuold bring any other os to its knees. iRMX trapped the hardware failure, recovered and kept going. One such event was a failed stick of DDR memory. iRMX paused for a few seconds , interrogated the memory controller and found parity errors in a whole bank of memory. It marked the affected address blocks as 'bad' ( like it would mark a drive sector bad ) , found out what was loaded there , reloaded that from disk , and then kept going. The machine did not shut down or lock up. A log entry was made that addresses x to y were bad and should not be used with a notification that on the next planned shutdown the memory should be replaced. a couple of days later the machine scheduled for planned takedown and maintenance and that's when we replaced the failed dimm.

Any single bit error in any other operating system would have catastrophical consequences. not in iRMX. it simply shrugs , and moves on
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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #17 on: August 03, 2012, 08:51:54 pm »
"The rover is powered by radioactive plutonium-238. As the plutonium undergoes decay, its heat is converted into electricity to power the rover’s electronic devices."

Are you telling me that this sucker is nuclear?
 

Offline madworm

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #18 on: August 03, 2012, 09:12:12 pm »
A thermo-nuclear battery, much like on the voyager I think. Basically works as a reversed peltier element.
 

Offline Chasm

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #19 on: August 03, 2012, 09:22:29 pm »
Exactly. Albeit with a different design (~110W el, ~2000W thermal) and only one instead of 3 as with Voyager (~160W el, 2400W thermal - each).

The Viking 1 and 2 Mars landers also used Radioisotope Thermal Generators. (2 each, ~50W el, 525W thermal)

RTG are used because there is simply not enough light to power such a large rover (and energy hungry experiments). The heat can also be used to heat the rover.
The other rovers also used radioactive elements to heat critical bearings like the wheels but had to use battery power to heat the rest. Small Radiothermal heating elements are quite common in space applications.
 

Offline KTP

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #20 on: August 03, 2012, 09:57:14 pm »
A thermo-nuclear battery, much like on the voyager I think. Basically works as a reversed peltier element.

Voyager is still working, sending back data so I think the nuclear battery is proven.

Would be interesting if this rover is working 34 years from now.  Kind of reminds me of Wall-e.  Maybe it can meet up with Opportunity and go on a date.
 

Offline free_electron

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #21 on: August 03, 2012, 10:25:51 pm »
Are you telling me that this sucker is nuclear?

no,no,no this suckers electrical, we just need the plutonium to generate the 1.21 jigawatts into the flux capacito.. oh wait.. wrong movie ...
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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #22 on: August 03, 2012, 10:33:40 pm »
Are you telling me that this sucker is nuclear?

no,no,no this suckers electrical, we just need the plutonium to generate the 1.21 jigawatts into the flux capacito.. oh wait.. wrong movie ...

hehe
 

Offline hobbs

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #23 on: August 04, 2012, 01:23:47 am »
I wonder if it would be possible to create a network of space relays, deployed in various area of our solar system, which would amplify  the signal from the satellites, so we would get better data quality ? Or would it kill the entire NASA budget ? ;)

Check out George O. Smith's *Venus Equilateral* stories for pointers on how to make that work. ;)

Cheers

Phil Hobbs
 

Offline dreamgame

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Re: EEVblog #328 - Curiosity Mars Rover Landing
« Reply #24 on: August 04, 2012, 11:06:27 pm »
 


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