Print 77 comment(s) - last by johnsmith9875.. on Aug 14 at 4:12 PM


Mike Ravine, Advanced Projects Manager for Malin Space Science Systems  (Source: torynfarr/flickr)

A two-image panorama shot with the rover's 1024 x 1024 mono navigation cameras  (Source: NASA)
Reasons included the amount of data produced, the fact that they had to meet the needs of different cameras, and the team's familiarity with these sensors

NASA recently accomplished a huge feat by landing its Mars rover Curiosity on the Red Planet, but one of the questions on the minds of many was why such a sophisticated machine used 2 MP cameras.
Mike Ravine, a project manager from Malin Space Science Systems, was happy to answer that in an interview with Digital Photography Review. He said the main reasons for using 2 MP sensors in the cameras were the amount of data produced, the fact that they had to meet the needs of different cameras, and the team's familiarity with these sensors.
"There's a popular belief that projects like this are going to be very advanced, but there are things that mitigate against that," said Ravine. "These designs were proposed in 2004, and you don't get to propose one specification then go off and develop something else. Two MP with 8 GB of flash didn't sound too bad in 2004. But it doesn't compare well to what you get in an iPhone today."
The amount of data produced is a large reason for using 2 MP cameras. There just isn't enough bandwidth for anything more powerful because the cameras must share with other instruments. Curiosity sends data back to Earth via the UHF transmitter, which transmits to two spacecraft orbiting Mars. The data is then sent back to Earth, and this system only allows for 250 megabits per day to be shared amongst various instruments.
The 2 MP camera sensors also were the tools of choice for the use of four different cameras, including the MAHLI, MARDI and two Mastcams. Having four different sensors for each camera would be expensive and more difficult to maintain rather than having one type of sensor all across the board. 
The team's familiarity with the sensors was crucial, too. The team knew the behavior of Truesense imaging chips and Kodak's KAI-2020 chip, so it makes sense that they'd work with what they know. 
"We know how to clock them and drive them," said Ravine. "They're a very easy CCD to drive."
Other issues, like the low pixel count, are not an issue either since the two Mastcams will create images from multiple exposures. 
NASA rover Curiosity landed successfully on Mars earlier this week after launching from Cape Canaveral, Florida on November 26, 2011. Curiosity is a one-ton, nuclear-powered, Mini Cooper-sized science laboratory that will explore the Martian surface for the next two years. 

Source: Digital Photography Review

Comments     Threshold

This article is over a month old, voting and posting comments is disabled

RE: Still no reason why they couldn't put 8MP
By s12033722 on 8/9/2012 7:28:10 PM , Rating: 6
I am a digital camera design engineer. I've worked on quite a few scientific cameras similar to this. The Kodak (now Truesense) KAI series has had higher megapixel count imagers that would have been no problem to get rated for a mission like this, but the higher resolution would have come at the cost of power consumption, slower frame rate, larger size, and increased weight, all of which are much more important than resolution in this type of application. Resolution is really a fairly unimportant aspect of camera performance in these types of applications. Of much higher importance are how well the sensor converts light to electrons (quantum efficiency), low noise readout electronics, high full well capacity to allow good signal to noise ratios, linearity of the camera response, etc. Resolution is a very narrow, relatively useless aspect of camera performance that gets hyped up in the consumer space. The actual determining factor in overall system resolution is usually not the imager in the first place - it's the lens. If they knew their lens was going to limit them to the effective resolution of 2 MP, why put in a bigger sensor with all the tradeoffs that go with it just to over-sample the image blur?

Don't try to apply consumer-level understanding of cameras to a scientific instrument like this. There's so much more complexity in a real camera than what gets talked about at the consumer level that it's just useless.

RE: Still no reason why they couldn't put 8MP
By m51 on 8/10/2012 11:24:49 AM , Rating: 2
Excellent post.

I'd also point out that they did consider the need for higher resolution on MSL and addressed the problem by having two cameras on the mast with different focal length lenses, 34mm and 100mm. Longer lenses gives you even better resolution that increased pixel count. That coupled with photomosaic should more than do the job. I believe they will be downloading the full resolution Mastcam panorama in the next few days and it will be impressive.

Malin Space Science Systems had also built a pair of Mastcams with zoom lenses, but these were cancelled in March 2011 when it was deemed there was not enough time to fully test them out and integrate them on the vehicle before launch.

RE: Still no reason why they couldn't put 8MP
By EricMartello on 8/12/2012 5:45:46 AM , Rating: 2
The focal length of a lens does not affect resolution - it affects field of view and depth of field. The optical resolution of a lens is largely determined by the quality of the optics (glass) and the precision with which they are engineered and assembled.

By m51 on 8/14/2012 10:45:24 AM , Rating: 2
Focal length doesn't strictly affect resolution. However a longer focal length lens gives more amplification of the image. That allows you to resolve more detail at a distance with the compromise of reduced field of view. A telescope by any other name..

Reduced field of view can be accomodated with photo mosaics.

By EricMartello on 8/12/2012 5:40:36 AM , Rating: 2
Some guy claims to work for kodak...I guess we better believe him since this is the internet.

That being said I agree with most of what you said except you're downplaying the value if resolution a bit too much.

The better the lens' optical resolving capabilities, the more a high resolution sensor will benefit and a lower resolution sensor will experience diffraction...and even average lenses have higher optical resolution than 2 MP.

Quantum efficiency is more or less at its practical limit for current sensor technology, and higher sensor resolution does not necessarily translate to additional weight or power consumption.

The main benefit of a lower resolution sensor would be the ability to consolidate the an image processing ASIC onto the chip itself and thus simplify the overall design of the system...but a higher resolution sensor would yield more detail per shot. It really boils down to whether they want a lot of "ok" pics or fewer high-res exploration I'd opt for the most detail that's practical because we have missed potential discoveries in the past due to basic resolving limitations of our equipment.

"So if you want to save the planet, feel free to drive your Hummer. Just avoid the drive thru line at McDonalds." -- Michael Asher

Most Popular Articles5 Cases for iPhone 7 and 7 iPhone Plus
September 18, 2016, 10:08 AM
No More Turtlenecks - Try Snakables
September 19, 2016, 7:44 AM
ADHD Diagnosis and Treatment in Children: Problem or Paranoia?
September 19, 2016, 5:30 AM
Walmart may get "Robot Shopping Carts?"
September 17, 2016, 6:01 AM
Automaker Porsche may expand range of Panamera Coupe design.
September 18, 2016, 11:00 AM

Copyright 2016 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki