Countdown to curiosity.

[Dave]

It's Tatooine!

I'm sure I just saw two droids coming your way.

 

[Vertigo]

Hehe - I can see that Dave! Works even better if you access the full panorama image. I won't paste it in directly as it's a little bit big. The black areas are where they haven't yet downloaded the hires images for those sections.
http://mars.jpl.nasa.gov/msl/images/pia16051_figure_1_raw_smaller-br2.jpg

Funnily enough my first impresson from the one above (not so much the whole panorama though) was of the Martian scenery at the end of Total Recall.

Incidentally Mount Sharp is in the centre of the image but off the top of it. And the dark area below it's slopes is an area of dunes, which, if I've got it right, they are planning to bypass either to their left or right.

 

[alchemist]

Are you following it on the MSL site Alc?

Afraid not, Vertigo. I saw those pics on another discussion forum and was so wowed by them that I had post here. You can just imagine walking through that desert.

 

[Vertigo]

Okay, well if you want to follow everything that is coming from Curiosity then it is all here: http://mars.jpl.nasa.gov/msl/

Oh and here's one of my favourite raw images (that is the tiles from which they make up the full panorama images). This one shows the bedrock which was exposed by the landing thrusters.

 

[Vertigo]

Latest word from the team is that they will probably have their first test drive in about a week. Note that it is not excatly going to be tearing along like a dune buggy; they expect to be driving at around 100m in a day!

 

[mosaix]

They've been using the past few days to upgrade computers, removing the redundant manoeuvring and landing software and replacing it with the software suitable for surface operations. Fascinating stuff. Who'd have thought they'd be doing remote upgrades at that kind of distance distance?

 

[Ursa major]

Let's hope that ieframe.dll hasn't just arrived on Mars....

 

[Venusian Broon]

They've been using the past few days to upgrade computers, removing the redundant manoeuvring and landing software and replacing it with the software suitable for surface operations. Fascinating stuff. Who'd have thought they'd be doing remote upgrades at that kind of distance distance?

Yeah it does seem a bit mad, but I'd guess they've been testing and re-testing, and testing and re-testing etc... the software while it was on the journery across to try and make it perfect, so that the really won't be any silly 'negative rather than a positive' kind of mistakes, or more complex nasties hiding in the code that might knock out the whole mission. It's happened in the past!

I'm sure they picked up loads of bugs (although I'm not sure we'd hear about them )

 

[alchemist]

But why do they need to replace all the software? Surely giving its electronics enough processing power to fulfil both functions would be a less risky operation than the brain transplant?

 

[Venusian Broon]

But why do they need to replace all the software? Surely giving its electronics enough processing power to fulfil both functions would be a less risky operation than the brain transplant?

Honestly don't know - perhaps they are working with really hard constraints on the hardware and the software is mind-boggling complex. (would be fascinating if we had any interplanatery craft builders on the forum that could answer such questions)

Perhaps they also remove bits they don't want anymore so they had maximum space for future upgrades, memory storage and perhaps ensure that they didn't accidently run dud applications that were never going to be used again but if activited might cause some chaotic behavour?

 

[Vertigo]

The new software that has just been installed was actually sent to Curiosity and stored in memory whilst it was on route to Mars.

The installation process was pretty secure. They have two computers: a main one and a redundant back up one. They installed on the main one first then tested everything, whilst still having the back up to fall back on if problems occurred. Once they were satisfied with that they did the same on the backup computer. So not too risky.

As to why, the original software was optimised for getting to and landing on Mars. As I understand it, Curiosity actually controlled the entire spacecraft for the duration of the flight. There was basic driving and science software as well but I think there wasn't room to have software doing both jobs optimally. All that flight software, being now redundant, could be binned, freeing up resources for much better driving and science software.

Bearing in mind the duration of the planned mission, I wouldn't be surprised if the whole process is repeated several times with new and improved versions of the software.

Bottom line it all probably comes down to space and weight. Not just weight in flight but also they want to minimise how much power is required for driving around. Their power pack doesn't have that much spare. For example the transmitter that sends data back to Earth is just TEN watts!!!! And we can pick that signal up from here after passing through two atmospheres. Compare with the average FM radio station transmitter that is, I believe, typically around 50kW.

 

[Metryq]

For example the transmitter that sends data back to Earth is just TEN watts!!!!

I haven't looked at the technical specs for the mission. Is that 10w transmitter on Curiosity and sending direct to Earth, or does it communicate to an orbiter which relays to Earth?

Still, that sounds like the kind of figure journalists love to toss around to wow the readers. Terrestrial transmission—with hills, trees, atmospheric effects, moving receivers, etc.—is quite different. And how do the "baud" rates compare? I believe the transmitters on the Voyagers are 23 watts. Inverse square that one, and it's very impressive.

 

[Venusian Broon]

Still, that sounds like the kind of figure journalists love to toss around to wow the readers..

Precisely, what is amazing IMO (and what has ensured that we've been able to 'hear' the voyagers all this time) is our listening ability and the advances that have been made there.

I don't know about the orbital characteristics of the mars orbiter (I wouldn't think that it makes sense for it to be geostationary, if it's part of its mission is to take measurements of the surface - that'd cut out half the planet), so I guess at the very least for redunancy reasons they'll be able to pick up signals directly from curiosity and communicate, (in fact may be for very good reasons that that it's the main route - don't know!)

 

[Vertigo]

I believe Curiosity communicates directly with Earth when it can and when it is on the far side of Mars it uses one or both of the two current Mars orbiters to relay the signal.

I appreciate that the dynamics of radio transmission in space is very different but don't forget the signal is having to travel through two lots of atmosphere as opposed to one lot. Also don't forget that the inverse square law refers to a point light source that is propogating as an expanding sphere. Here we are talking about signals focused by a dish so the drop in signal is mainly due to atmosphere rather than the exapnsion and so 'dilution' of the radio beam. Even so detecting a ten Watt source at around 250 million kilometres is pretty darn impressive however you look at it.

 

[Metryq]

Deep Dish Pizza, er, Deep Space Network

 

[RJM Corbet]

And the plutonium 238 power unit is not a plutonium 239 fission reactor:

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

 

[mosaix]

Looks like the landing wasn't totally perfect. They think some damage has been sustained from stones thrown up by the skycrane jets...

http://www.bbc.co.uk/news/science-environment-19338870

 

[alchemist]

Yeah, yeah, jets. Local hooligans, more like.

 

[Metryq]

Curiosity's wind sock torn from its mast. Film at 11.

 

[mosaix]

In a nice touch from NASA the Curiosity landing site has been named Bradbury Landing after Ray Bradbury.

http://www.bbc.co.uk/news/science-environment-19342994

NASA have also reported that one of the rovers wheels came down on a 9cm high rock. That it sustained no damage is yet another tribute to the design engineers.