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Mars rover camera project manager explains 2MP camera choice

By dpreview staff on Aug 8, 2012 at 22:20 GMT

A number of factors led to the use of 2MP sensors in the main imaging cameras used on NASA's Mars rover, Curiosity, says the project manager responsible for their development. The slow data rates available for broadcasting images back to Earth and the team's familiarity with that family of sensors played a part, says Malin Space Science Systems' Mike Ravine, but the biggest factor was the specifications being fixed as far back as 2004. Multi-shot panoramas will see the cameras deliver high-res images, he explains, but not the 3D movies Hollywood director James Cameron had wanted.

'There's a popular belief that projects like this are going to be very advanced but there are things that mitigate against that. These designs were proposed in 2004, and you don't get to propose one specification and then go off and develop something else. 2MP with 8GB of flash [memory] didn't sound too bad in 2004. But it doesn't compare well to what you get in an iPhone today.'

The 34mm (115mm equiv.) Mastcam from the Curiosity rover - developed by Mike Ravine and his team at Malin Space Science Systems.

The first consideration when choosing a sensor was the amount of data it would produce.

There are three ways for Curiosity, to broadcast data back to Earth - but it's only the UHF transmitter that can be used for transmitting the amounts of data required for sending back images. 'The UHF antenna transmits to two spacecraft orbiting Mars, which relay the results back to Earth. That's where most of the data is coming from. It gives us on the order of 250 megabits per day, and that's got to be shared between a bunch of instruments, so there's not much bandwidth for the cameras.' Ravine explains.

Another factor was that the same sensor had to meet the needs of four different cameras (MAHLI, the two Mastcams and MARDI, the camera tasked with capturing the rover's descent to the planets' surface). 'Everything in a project like this is sensitive to price and risk, both real and perceived. The cameras differ in terms of their optics, but by building them around a single platform, we didn't have to re-test and qualify each of them separately. This makes them more dependable and less expensive than if you have to do it four times.'

'We developed all four cameras around a common architecture so the choice of sensor was hedged across all of them. We wanted to be able to capture high frame rates, particularly with the descent camera.' he explains. MARDI, the downwards-pointing 'descent camera' had just a two-minute descent to the planet's surface, so a high frame rate was essential. The KAI-2020 chip was the smallest Kodak made capable of 720p HD video. 'We also looked at a 4MP sensor but it would have run around half as fast. And the state of CMOS sensors wasn't credible in 2004. They're an interesting option now, but they weren't then.'

The initial thumbnail image from the MARDI descent camera, showing the heat shield dropping away, just before the final descent begins. Click here to see a video of the heat shield falling away, based on these thumbnail images.
Image Credit: NASA/JPL-Caltech/MSSS

The other advantage of the Truesense Imaging chips was the team's familiarity with their behavior. 'We've built-up decades of cumulative experience of working with Kodak and now Truesense interline sensors. We know how to clock them and drive them - they're a very easy CCD to drive,' says Ravine. A similar level of confidence was needed for the cameras’ memory, he says: 'the flash we ended up using was because we had a lot of radiation test data for it.'

 The full-resolution image, released August 8th, giving a clearer idea of what the 2MP cameras onboard the Curiosity rover with be capable of.
Image Credit: NASA/JPL-Caltech/MSSS

And the low (by modern standards) pixel count needn't be a problem, Ravine says, since the Mastcams will produce stitched images from multiple exposures. 'A mosaic produced from a higher pixel count camera wouldn't offer huge benefits over what we'll be getting.'

Ravine is understandably proud of the work his team has contributed to the project, on the day the rover's mast is raised for the first time: 'We're getting pictures from Mars,' he points out. But it's not hard to detect a note of disappointment in his voice when he mentions the zoom lenses that were being prepared for the project: 'they're currently sitting in a container on the other side of the building.'

Sadly, the cancellation of the zoom lens project for MSL means that it won't produce the 3D footage the team originally hoped for. 'They were going to be 6.5-100mm zoom lenses, which would allow us to set them both to the same focal length for capturing stereo images,' he says. However, problems designing the lens without using wet lubricants (which would require battery-sapping heating to ensure continued operation in Mars' extremely low temperatures), proved difficult and the development was halted.

The benefits of stitching: a two-image panorama shot with the rover's 1024 x 1024 mono navigation cameras. The Mastcams should produce higher-resolution, color images.
Image Credit: NASA/JPL-Caltech

Hollywood director James Cameron was part of the team and successfully lobbied NASA to re-start the zoom project, with talk of 3D movies showing Curiosity's progress across the Martian landscape. Sadly, although the project was re-started, even Cameron's enthusiasm wasn't enough to ensure they'd be ready in time. 'We're going to get some great mosaics with the focal lengths we've got, but we're not going to get the wide-field cinematic moments or the 3D movies from Mars that Cameron wanted.'

Another perspective - polar projection of the rover's deck and its surroundings. The image is composed of low-res thumbnails, except the two full res panels used in the image further up the page.
Image Credit: NASA/JPL-Caltech

Comments

Total comments: 187
12
Mathias Japri
By Mathias Japri (Aug 9, 2012)

Just wondering, mars is full of snad dust particels etc, how does this camera manage to get it's lens clean from dust and etc.

imagine a 4x4 travelling in desert, the whole car would be covered all in dust...

does in mars have strong wind also?

0 upvotes
Hynee
By Hynee (Aug 9, 2012)

They point the mastcam lenses down when they aren't being used. They will get a bit of dust on them, but there are "cleaning events" which periodically get the dust off the lenses, and on the MER rovers cleaned the solar panels.
Opportunity rover has been active for 8 years and its lenses are still going strong.

3 upvotes
Sunny15
By Sunny15 (Aug 9, 2012)

In addition, its top speed is about 1.5 inches per second, so it won't be kicking up that much dust.

1 upvote
Edmond Leung
By Edmond Leung (Aug 9, 2012)

Excellent job! NASA.
Crystal sharp images from those 2MP cameras, so fantastic!
What can I say is perfect image sensor, perfect lens, perfect design and perfect engineering.
This $2.5B project is not only a proud of America, it is also a proud of all human beings on the Earth.

6 upvotes
Fogsville
By Fogsville (Aug 9, 2012)

These images are so awesome.

And I'm actually glad Cameron's 3-D entertainment game didn't end up in the mix. I think it's better that Hollywood doesn't get to cash in on this.

The real deal are the men and women at JPL and CalTech. They know how to get it done even while on a tight budget and schedule. That's what ingenuity is all about.

3 upvotes
Paul Farace
By Paul Farace (Aug 9, 2012)

I agree with your points, but I have to make one of my own... this way (no computer game from Cameron) NOBODY under age 25 will give a fiddler's fart for the Mars rover or see any image beyond what the press is pushing today. We have lost our next generation to the most powerful, brain killing drug of all... computer GAMES!

1 upvote
KentG
By KentG (Aug 9, 2012)

Then its no wonder that the rest of the world is going by us in math and science.

Comment edited 16 seconds after posting
0 upvotes
Fogsville
By Fogsville (Aug 9, 2012)

Just for the record, when I said Cameron's "3-D entertainment game" I didn't mean a literal "game" in the sense of a computer game. I meant it in the sense of his 'game' of making everything into entertainment (he's a film director/producer.) i.e., making a 3-D movie with images from the Mars rover. These are images that belong to us and shouldn't be commercialized into the Hollywood profit generating 'game.'

Cameron doesn't make computer games, he makes films and is a big advocate of 3-D film production. But that said, there are plenty of young people under 25 who are quite intelligent and find science and math fascinating. And the team at NASA's JPL is a big inspiration to them.

Comment edited 2 times, last edit 2 minutes after posting
0 upvotes
Sam Carriere
By Sam Carriere (Aug 9, 2012)

It would be wonderful is Dpreview left this NASA boondoggle to the newspapers and concentrated on matters of interest to photographers.

0 upvotes
Photomonkey
By Photomonkey (Aug 9, 2012)

As a photo oriented site it is perfectly appropriate and more importantly provides real insight into how the scientific imaging professionals get the job done. It is science like this that actually moves Earth technology forward.
Without the space program you would have had to type your message and post it to the newspaper where it would not get published.

14 upvotes
tirmite
By tirmite (Aug 9, 2012)

And what exactly is the "boondoggle" that NASA has committed?

4 upvotes
Tee1up
By Tee1up (Aug 9, 2012)

A story about NASA's sensor choice is completely appropriate.
You have become jaded Sam.

3 upvotes
robmanueb
By robmanueb (Aug 9, 2012)

This story is so irrelevant I had to read it and comment... Fail Sam.

1 upvote
BartyLobethal
By BartyLobethal (Aug 9, 2012)

I'm a photographer. This article is about photography. I find this interesting.

2 upvotes
framus
By framus (Aug 9, 2012)

Way to go Sam Carriere! Stay classy. Keep that Spam wagon rolling.
Not to worry though, school resumes in a few short weeks and you can get back to your true intellectual pursuits.
-Framus

0 upvotes
DogOfThunder
By DogOfThunder (Aug 9, 2012)

DPReview needs a "Dislike" button just for posts like yours.

DISLIKE

0 upvotes
Keith Golon
By Keith Golon (Aug 9, 2012)

For everyone complaining about low resolution and bandwidth..

Strap your iphone to the camera mast and see how long it functions. I don't doubt it will take a few pictures right away, but what about next week? Understand that space qualified cameras are just a little bit better engineered than the consumer garbage you keep in your pocket. Understand that NASA doesn't flood a data connection with trash pop-ups and useless java ads. They don't stream google-ads either. So they can do a lot more with 250MB daily than you can.

4 upvotes
bizi clop
By bizi clop (Aug 9, 2012)

That's not 250MByte. It is 250 mega-bits = 250/8 = only 31.2 megabyte data per day.

0 upvotes
meerkats
By meerkats (Aug 9, 2012)

Nasa is not a newspaper publisher.
What will you do if you're the manager of Mar's rover project, getting data for the scientists, or satisfying the public with some higher resolution pictures?

1 upvote
alanjdooley
By alanjdooley (Aug 9, 2012)

Let's see -- without any other considerations, using Nikon as a baseline, when the scientists made the decision in 2004, we could have chosen from the D2H, D100 or D70. Now -- add a lens of choice and instrumentation to point it, trigger it, etc., make it solid enough to survive a multi-G take off, a 350 million mile journey through the radiation-laced vacume of space and a rentry... it sounds to me like the engineers did a pretty decent job in 2004. And if they had chosen the state of the art commecial camera, it probably wouldn't work now anyhow. Remember, pretty pictures are really only to keep the public off NASA's back while they conduct real science. We will be amazed in coming days and months, just as we still are with images from another rover that's been their 8 years now, sitting outside in a hostile environment. For those who are already complaining -- my Daddy always told me, "Some people would gripe if you hung them with a brand new rope." HANG in there, complainers!

Comment edited 2 times, last edit 2 minutes after posting
1 upvote
pedroboe100
By pedroboe100 (Aug 9, 2012)

To those who complain about the quality of the equipment, go look at some Ansel adams stuff. Besides, the goal is a little more altruistic, for the benefit of mankind, not so NASA could enter a DPreview "Challenge".

So far they are the ones taking the best pictures of Mars on location.

4 upvotes
tkbslc
By tkbslc (Aug 10, 2012)

Well I agree with your sentiment, but Ansel shot large and medium format which would equate to very high resolution in digital terms.

0 upvotes
duartix
By duartix (Aug 9, 2012)

Has anyone done the math on how much $$ a dead pixel will cost?

0 upvotes
SunflowerFly
By SunflowerFly (Aug 9, 2012)

The computer on board:
200MHz G3, 256MB RAM, 2GB SSD drive (yes, seriously), VxWorks OS.

0 upvotes
jgardia
By jgardia (Aug 9, 2012)

It is the fastest radiation shielded computer you can find.

4 upvotes
mister_roboto
By mister_roboto (Aug 9, 2012)

an iPhone would have some trouble working on Mars- I hear they don't have LTE yet.

0 upvotes
JerryZaza
By JerryZaza (Aug 11, 2012)

Actually at the last press conference the Engineer for the software stated that it was a "120 Mhz MicroProcessor"
Which is not to be laughed at, you would be amazed what that machine can do if you write code for it in Assembler Language (most compact and efficient) or a well optimized C++ code compiler.
Without all the added junk and inherent inefficienties of an OS like Windows adds that processor is very powerful.

0 upvotes
Mike Sandman
By Mike Sandman (Aug 9, 2012)

The morning after the landing, while having breakfast. I opened up the New York Times' mobile edition on my iPhone and looked at a B&W photo sent from Mars after the camera traveled 353 million miles.

It's great to see dPreview publish information about the camera, and it's REALLY amazing to see the images. Thank you, NASA!

2 upvotes
anthony mazzeri
By anthony mazzeri (Aug 9, 2012)

Very 2001: A Space Odyssey-ish.

0 upvotes
prohidium
By prohidium (Aug 9, 2012)

250 megabits is roughly 31 megabytes of data over a 24 hour period. They must be using jpg compression to make it worth while. That is not very much data at all. It is about 2.9Kb per second or 2900 baud. That was the speed of data on earth in about 1986. I suspect the actual speed might be higher but there are probably some blackout periods through the day where the orbiting relays do not line up well and they can't transmit at full speed.

Comment edited 58 seconds after posting
2 upvotes
JerryZaza
By JerryZaza (Aug 11, 2012)

Uhm when they state an available bandwidth/day that takes into account any blackouts that happen during that day. And no there is no compression on data as someone as pointed out JPEG is a lossy compression algorithm i.e. You loose information with it the more you compress the more you loose. NASA has developed over the years algorithms that compress data without loss. But I would imagine that they are applied to the Data Stream itself, also the same algorithms need to cope with any errors that might occur during transmission. We are talking about receiving data from 300 million kilometers after all.

0 upvotes
jcb9001
By jcb9001 (Aug 9, 2012)

Maybe next time they should put a 4x5, film, a minilab, and an Epson V750 flatbed scanner on the rover.

Seriously, if this Cameron fellow wants 3d movies, he can build his own rover and send it to Mars. What is stopping him?

2 upvotes
Tonio Loewald
By Tonio Loewald (Aug 9, 2012)

Seriously?

You do realize that Cameron has been doing deep sea research β€” including designing and building a unique submarine on his own dime β€” and just completed the first trip to the bottom of the Marianas Trench in over fifty years. You think he's a rich jerk who attends meetings and whines about cameras? Or maybe he's lame because he isn't building his own Mars expedition in his copious free time?

Comment edited 33 seconds after posting
8 upvotes
Klarno
By Klarno (Aug 9, 2012)

Interestingly, during the cold war, Kodak developed spy satellites that used large format film, an onboard minilab, and a telecine to beam the pictures back to earth.

0 upvotes
Sunny15
By Sunny15 (Aug 9, 2012)

The Soviet Union used this process before, on early moon probes, Luna 3 being an example. Not with 4x5, though :-)

I think NASA did too, though I don't recall which spacecraft used it.

Comment edited 7 minutes after posting
1 upvote
cleverinstigator
By cleverinstigator (Aug 9, 2012)

I'm sorry why not put up a few satellite relays in between so we can get some decent images of the planet why spend that much money on a mission that is 8 years behind in sensor technology. 2mp is a joke for landscape shots.

1 upvote
Tonio Loewald
By Tonio Loewald (Aug 9, 2012)

Whose previous post included this quotation:

β€œAny fool can criticize, condemn and complain and most fools do.” Benjamin Franklin

You did.

16 upvotes
ajamess
By ajamess (Aug 9, 2012)

Are you daft?

Take a read about the history of cameras in space before you make a fool of yourself again, then maybe you'll realize how big of a deal it is that they are actually including as good a camera as they did:

http://www.mentallandscape.com/V_Cameras.htm

Just because this is a camera forum doesn't mean you need to belittle actual scientists' work just because they aren't throwing a D800 on board.

0 upvotes
ZorSy
By ZorSy (Aug 9, 2012)

MAte, this thing isn't there to take images of sunsets or distant mountains with grassy meadows in the foreground, resolving every strand of grass, every leaf and every petal of the flowers that ain't there. It's there to look the traces of lifeforms that may had existed before global magnetic field collapsed several billion years ago, resulting in erosion of Mars atmosphere and end of (eventual) life. No fancy HDR panoramas, no ET portraits - just boooring science. 2MP will do for now....

1 upvote
tirmite
By tirmite (Aug 9, 2012)

I went to the trouble of signing up JUST TO RESPOND to the brainless, idiotic statement above. Obviously you're a rocket scientist and genius, right? You were SO smart that NASA had to let you go I guess.
"A few satellite relays" Oops, they forgot to do that! They already have a few up there from years ago at an enormous cost. It's not like Sprint digging a hole & putting up a new cell tower. And if you read the story with ANY comprehension you'd see that projects like this are planned and budgeted YEARS in advance. And it's STILL state of the art. I don't see any competitors on the surface of Mars, do you? Or maybe you built something better in your basement and it's on its way up there now? I can only hope you're a child and not an adult with that sort of noodle inside your skull. FYI: it's also 350 MILLION miles away!!!! That's 14,000 times the circumference of your planet, assuming you're from Earth. I'm so sick of the stupidity and stupid remarks in these forums.

6 upvotes
Klarno
By Klarno (Aug 9, 2012)

Luckily, the lenses of the cameras on Curiosity have a very long EFL. you can expect gigapixel panoramas in short order.

2 upvotes
Harold Olivier
By Harold Olivier (Aug 9, 2012)

for tirmite, who wrote that Mars is 350 million miles away, it can't be. Mars is never more than 249 million miles from Earth, and the distance between Mars and Earth right now is 'only' 156 million miles.

0 upvotes
Andy Crowe
By Andy Crowe (Aug 9, 2012)

Did you not read the "Multi-shot panoramas will see the cameras deliver high-res images" bit?

The cameras are mounted on a motorised platform designed for taking automatic panoramas, so they can get a lot more resolution out of them than just single 2 mp shots.

You really shouldn't comment on things if you haven't bothered reading literally the first paragraph.

0 upvotes
DoryD
By DoryD (Aug 9, 2012)

If the guy had any idea how gravity works, he wouldn't have asked to "put up a feel satellite relays". Satellites don't just "sit" there in space like a cell tower...

0 upvotes
hc44
By hc44 (Aug 10, 2012)

It's OK they've got a panorama shot mode. Still not as good as Sony NEX though, you can see the joins on the NASA shots.

0 upvotes
JerryZaza
By JerryZaza (Aug 11, 2012)

Well for starters, the Earth and Mars revolve around our Sun at different speeds. the Martian Year is about twice the length of Earth's. That is why the "Primary Mission" has to last 2 Years (Earth) or 1 complete season for Mars.
So the distance from Earth to Mars is constantly changing.
And as a result you can't place "repeaters" between Earth and Mars. The best we can do and NASA DID is to place some repeaters around Mars itself. Actually NASA has 2 and ESA will add a 3rd.

0 upvotes
wkay
By wkay (Aug 9, 2012)

yes, bandwidth and reliability have to rule, combined with state of the art 2004 technology. Must survive very high G's of takeoff and landing, extremes in temperature, and interplanetary radiation level (rad-hard). This is not simple to design and qualfiy. Sensor performance must be extremely well understood. Failure is not an option because you guessed something was good enough. HD video requires only 2M pixel count and anything else can be stitched.

8 upvotes
RaZZ3R Death
By RaZZ3R Death (Aug 8, 2012)

In the future I hope that compression algorithems advance enough so we can enjoy at least 5 to 10 MP at file size of 1-2 MB as JPEG. And maybe they can use oversizes senzors for better DR so they can be processed for better IQ (not just for the public viewing but allso fo science studies). I guess it's not in my lifetime to be able tu fufill my ultimate dream: NAVIGATE INTO THE DEEP SPACE OF UNKNOWN, but seeing the progress of sciente and humanity give me hope for a better future beyound this "booring rock". And like a plague we shall descent upon the planets and the stars into galaxys and beyound small beginig that once this little race of men started with just a flaming torch of inginuety and a burning hear of curiosty ...

0 upvotes
bizi clop
By bizi clop (Aug 9, 2012)

Algorithms are coming from scientists researching "compressed sensing": http://nuit-blanche.blogspot.com/

0 upvotes
Guerito
By Guerito (Aug 8, 2012)

The truth is that NASA has a 250MB daily cap. ;-)

3 upvotes
cosmokanga2
By cosmokanga2 (Aug 9, 2012)

250 megabits or 31.25 megabytes (MB), sorry. Talk about a bandwidth cap.

1 upvote
Mssimo
By Mssimo (Aug 9, 2012)

They should really switch over to Sprint. That data limit sucks.

4 upvotes
Klarno
By Klarno (Aug 9, 2012)

Sure, Sprint would give them unlimited data, but also nonexistent rural coverage. And I don't think two having two relay satellites qualifies Mars as urban...

3 upvotes
OldDigiman
By OldDigiman (Aug 8, 2012)

Take a look at the photos produced by the Mars rovers Spirit and Opportunity, which only had ONE megapixel cameras and see how much information is there. "Postcards From Mars" is the book that has them. 2MP and newer technology can only be better.

3 upvotes
BozillaNZ
By BozillaNZ (Aug 8, 2012)

Jebus, This is what happens when you post this news on a camera whore forum, everyone brag about this 2MP 'issue'!

Further more, if you have done primary school algebra, you would know that the supposed "Full HD" resolution of the grand 1920x1080 is exactly 2MP! Now get a hammer and smash all your "Full HD" resolution devices because they are sooooo low spec-ed! Yeah!

Comment edited 3 times, last edit 2 minutes after posting
9 upvotes
Mssimo
By Mssimo (Aug 8, 2012)

2.5 billion dollars for a 2MP camera? Really NASA?

3 upvotes
Richard Butler
By Richard Butler (Aug 8, 2012)

Did you read the article?

Do you understand why they had to set the specification in 2004 (originally for a 2009 launch)?

And that they have to get the data from these cameras, and all the other experimental instruments, back from another planet?

20 upvotes
DRG
By DRG (Aug 8, 2012)

And that all electronics for a spacecraft have to been radiation hardened.

1 upvote
robmanueb
By robmanueb (Aug 8, 2012)

2.5 billion dollars for the whole project not just for the camera.

Comment edited 2 minutes after posting
7 upvotes
KZMike
By KZMike (Aug 8, 2012)

READ THE ARTICLE. . . one does not take current off the shelf equipment, memory, and sensors and put them out where they get the full 'blast' of radiation and other impacts from solar flares and expect that sort of items to function for more than a few minutes.

It will amaze you. . . well maybe not you. . . but the rest of us will I'm sure, on what NASA will be able tp put out once ALL the systems have been tested and put to work.

If you would take a moment and think about it, in the past fly by's to the outer solar system planets, NASA utilized much more primitive sensors and brought us back SPECTACULAR Photos.

Opps sorry asking that is beyond what your statement indicates

The $2.5 B,bought MORE than the single sensor you denigrate

Comment edited 55 seconds after posting
0 upvotes
Mssimo
By Mssimo (Aug 8, 2012)

I did read the whole article and I'm still excited to see what they can do with this tiny camera. I'm also sure the they have many filter for all types of lights/radiation.

1 upvote
osage_archer
By osage_archer (Aug 8, 2012)

And $2.5 billion is about what the US Government now spends (wastes) in just one-half a day...

0 upvotes
JordanAT
By JordanAT (Aug 9, 2012)

2MP Custom CCD camera: $2,000,000
Spacecraft to get to Mars: $2,498,000,000
Arriving at a destination after a 300 million mile trip, touching down softly, and sending pictures of an alien world back: Priceless

3 upvotes
tim73
By tim73 (Aug 9, 2012)

Well you get a motorized tripod too. And wifi. :-)

1 upvote
Superka
By Superka (Aug 8, 2012)

Ok, we''ll wait for a man on Mars, with Canon.

4 upvotes
peevee1
By peevee1 (Aug 8, 2012)

As the things are going, it will be a Chinese man, with Huawei.

7 upvotes
jvideographer
By jvideographer (Aug 9, 2012)

I respect the scientists who achieved this amazing feat.
I presume they know what they are doing since they are, after all "rocket scientists."
And please remember, I believe they are getting the main scientific data not from the camera but from other devices. The camera is there to help the operators navigate, for one thing. I think it can do that quite well.

1 upvote
BozillaNZ
By BozillaNZ (Aug 9, 2012)

Yeah, that man will be the first to have ERR99 on Mars! LOL!

1 upvote
Litebright
By Litebright (Aug 9, 2012)

Another consideration is radiation from the sun with no atmosphere to block it. Not that long ago, just going into our outer atmosphere, NASA had to use very old computer processors like 286 chips when the Pentium was out because it's die was larger and it could withstand being bombarded by large particles better. I imagine the use of the 2MP cameras wasn't just because of the data issues.

Comment edited 2 minutes after posting
3 upvotes
Total comments: 187
12