I came across this on Reddit the other day, taken with a smartphone and 8" telescope: https://www.reddit.com/r/astrophotography/comments/4kegyv/sm...
This one is fairly low res and grainy.
This isn't a photo. It a photoshop fiction of 400 different photos blended together. There's a big difference between that and a single frame from a spacecraft. Comparing the two seems silly.
Stacking improves signal-to-noise ratio but does not introduce details that aren't present. A stacked image can be more accurate than a single frame as camera artifacts are reduced.
Your typical single-frame exposure involves a great number of processing operations and filtering that may be unknown to most people, but still define the "look" of the end product (which is nowhere close to a 1:1 representation of the light entering the lens).
The basic problem of all astronomy from Earth's surfaces is that the atmosphere impedes seeing. So much so that even small backyard telescopes rapidly reach the limit of atmospheric seeing before hitting the limits of diffraction. There are several ways around this. One is to leave the atmosphere entirely, resulting in the stunning capabilities of space based observatories like Hubble. Another is adaptive optics, which relies on various techniques to read the atmospheric disturbance causing degraded seeing and precisely counteracting it by interposing a reactive optical element.
The technique in question is basically a sort of poor man's adaptive optics related to speckle imaging (another technique employed for the same purpose). For bright objects (like planets) an image exposure using modern CCDs need only be a fraction of a second. Which provides the opportunity to collect many of them over a period of time, which is something that many cameras already do quite well by recording video. The alternative of counteracting poor atmospheric seeing is to hope you get lucky and capture a moment where atmospheric distortion is at a minimum. Such moments are rare and fleeting, but over the course of hundreds or thousands of images from a video stream, there will be a few. The trick is to find the best moments of seeing for a given portion of the image from within the frames and combine all of them together into a single image. You then have essentially a "dream team" of atmospheric seeing conditions for every part of the image. Every part is real, and the overall image is a true representation, not a fantasy.
However, your point about the futility of comparing the two is accurate. Comparing a single image from Juno to the best thing produced from a backyard astronomer ever is not a good comparison. Especially since Juno will collect a great many more pictures and is not at all optimized for taking pictures at its current distance from Jupiter. The best pictures of Jupiter from Juno will outclass anything we've taken with any instrument from any observatory or spacecraft so far, but it'll be a while yet before we have those.
I now see that the link has been edited/changed Carry on!
I wish they mark these pics with some pictographs regarding the scale of things. Like something comparing the orbital distances between the moons and Jupiter itself to that of Earth's orbital distance to the Sun or something. I cannot comprehend 4 million kilometers (which I know is Juno's distance to Jupiter, not the moons' orbital distance..). I have trouble wrapping my mind around just 4 km.
That's about 0.3% the distance of Earth to the Sun.
For a good sense of how enormous these differences are, try the video "Riding Light" - https://vimeo.com/117815404 - Jupiter shows up at the 43:10 mark (Earth's at 8:17, for size comparison).
To think there is a probe there now is a pretty powerful image to inspire children. Something we couldn't do with the recent Pluto visit, as awesome as that was.
My daughter's massively into space, and having a mid-size telescope (Celestron NexStar 6SE) has been truly wonderful. There's something really different about seeing it for yourself even if the picture isn't as good as one from a probe.
Any suggestions on how to start?
What else is in the pipeline?
NASA has been pretty active in public outreach. The article indicates that Juno takes something like 4 photos an hour. I wonder whether it will be 1 photo for the public to 3 photos for science, or totally different?
That's what you get from a solar powered probe. We waste billions of dollars and unique opportunities because some people have gotten in their minds that RTG power is evil and dangerous. NASA even canceled the ASRG, based on the Stirling engine, which was 5 times more efficient in terms of radioactive material and would have allowed powering probes for the whole solar system. Imagine a Pluto rover !
[1] https://www.nasa.gov/mission_pages/juno/spacecraft/index.htm...
https://www.nasa.gov/feature/jpl/nasa-s-juno-spacecraft-send...
Juno will be passing within 3,000 miles of the tops of Jupiter's clouds. Since Jupiter's radius is 43,000 miles, it will fill the entire frame. The only question is how high-quality the camera is.
The camera is for public relations only (no science) and I don't know the resolution. But this photo was taken from 2.7M miles, so you can expect the resolution to get roughly 9 thousand times better.
EDIT:
> Jupiter itself will only appear to be 75 pixels across from JunoCam when Juno reaches the furthest point of its orbit around the planet. At its closest approaches JunoCam could achieve 15 km/pixel resolution from 4300 km, while Hubble has taken images of up to 119 km/pixel from 600 million km....The camera uses a Kodak image sensor, the KODAK KAI-2020, capable of color imaging at 1600 x 1200 pixels. It has a field of view of 18 x 3.4 degrees with three filters to provide color imaging.
In comparison, the highest resolution photos of Pluto from New Horizons achieved 80 meters per pixel from a closest approach of 12500 km. Its amazing how good the camera was on New Horizons.
https://www.nasa.gov/feature/new-horizons-best-close-up-of-p...
This statement made my day. I guess if a phone must have a camera on it then a spacecraft has to have one too.
No. The camera on Juno was literally an after thought. Originally it wasn't even going to have one. It's main job is studying magnetic fields and radiation belts.
In addition to fields and radiation instruments you mention, there are two other imaging spectrographs, one an IR instrument and one in UV. The IR camera can look ~70 km down below the cloud tops.
Importantly, there is a microwave radiometer, which can peer ~500km beneath the clouds to determine atmospheric composition as a function of time and space.
They have put Juno in a polar orbit, so it will scan the atmosphere through dozens of orbits before the radiation kills the instruments.
Doubt we'll see depth, unless it's through fortuitous breaks in high clouds. Other (non-imaging) instruments (microwave sounders, etc.) will tell us what's going on in Jupiter's interior. Metallic hydrogen? Rocky core? Juno may tell us.
We don't know why the corona of the sun is hotter than the surface of the sun. SPP will provide data to help us to better understand and create better models of coronal heating and the solar wind.
I think it says a lot of great things about NASA that people consider putting a satellite in orbit around Jupiter to be routine. Further great things from the fact that they really want NASA to stop being "boring" and invent some crazy new thing and push the boundaries of what humans think is realistically possible again - after all its been like a whole year since they blew our minds last time.
All for the low price of ~.03 militaries. (Not including the fact that NASA does some stuff for the military...)
Asteroid redirect mission -- (https://www.nasa.gov/mission_pages/asteroids/initiative/inde...)
A Europa mission might resemble Cassini and Juno: orbiting the main planet with frequent flybys of the moon. This requires less fuel and keeps the probe in the dangerous radio belts less of the time.
NASA is fully cooperating with SpaceX by doing things like providing detailed data of previous Mars landings. NASA is SpaceX largest customer and financier. Many ex-NASA people workmat SpaceX. These data are public. But it helps to have good communication channels.
Is this budgeted? Is it on a launch docket? Is there a rocket ready for it? Is the lander completed? 2018 is right around the corner and frankly I'm getting sick of "Spacex might" comments. There's a big difference between "might" and "do." When you see a mission on the NASA roster, its ready to go and unless there's some serious technical issue, it'll happen.
I'd like to see more "do" from SpaceX that isn't LEO flights and landing on barges.
RTG usage is curbed due to NASA's low supply of plutonium-238. Until more is made it makes sense to design for solar powered systems. Also these are risky missions with high pricetags and erring on the side of caution using well known technologies isn't some big conspiracy. Its to avoid high-profile fails. We can try new and risky stuff in lower profile missions.
Heck, Curiosity was launched just a few years ago and has 11lbs of plutonium powering its RTG. I hardly see a conspiracy here. Also RTGs add weight and cost to projects. If you don't need one, you probably shouldn't be using one - even ignoring their rarity. Missions like Juno get significant weight savings using solar.
>I don't know if the cam is the problem or the transmission bandwidth,
The quality of the photo has to do with the distance from Jupiter. It has nothing to do with "power." This is a spacecraft, not a gaming PC. Yes more power would mean a higher bitrate, but the bitrate it uses is good enough for the mission.
If solar panels saved weight, they would have been used on past missions like Galileo. Better solar panel technology will eventually shift the balance, but we're not there yet. Juno's panels weigh 340kg. Galileo's two RTGs, which produced about the same amount of power at Jupiter, weighed 57kg each.
The fact is, it could be better, and it really should. It's just silly to use Solar panels in the outer Solar System. This mission was dominated by politics and not science. I think that is a very real issue. Look at Curiosity, I think it's very clear that Rover is a massive upgrade over the preceding solar powered missions.
At closest approach, Juno will be 2,200 miles from Jupiter, less than 1% of the distance between the Earth and Moon.
Space exploration is expensive, and a very large part of that expense is mass. Putting a 2.7 million mile scope on a probe that's going to be spending much of its time far closer in to interesting targets costs mass, and fuel, and other sensing apparatus you can't add. So there's that.
It's possible that there are higher-resolution capabilities for the probe as well, or that post-processing or higher data rates will improve current images.
It's also possible that visual reconnaissance wasn't a high priority for this mission, though I'm not familiar with the sensing platforms included.
Given orbital eccentricity, Juno can acquire and store high-quality data, and transmit that at leisure during the outbound parts of its orbit.
And yes, photos weren't a priority at all. If it were just a matter of returning scientifically useful data, they wouldn't have included this camera at all. But NASA likes pretty pictures too, so they included one.
EDIT: For a comparison to Hubble - at closest approach JunoCam will get 5 kilometers per pixel [1], while Hubble gets in the region of 120 kilometers per pixel [2]. So, giant jump in quality, though the field of view from up close will be limited.
[1] http://planetary.org/blogs/emily-lakdawalla/2011/3133.html
Or maybe that's not a problem.
However, you can do great things with a good pair of binoculars (and a steady hand). You can resolve planetary discs, pick out the moons of Jupiter, spot Neptune and Uranus if you're good (although I never have) and exploring the surface of the moon is endlessly fascinating. And if you're really desperate, you can look at birds through them.
There is a "gravity sensor" which is really, I think, an extremely careful Doppler measurement which will allow us to infer the mass distribution within Jupiter.
Well, everyone does. If it wasn't for this photo we wouldn't be discussing Juno here on HN nor would this mission be in the press right now.
It seems crazy to me not to put a camera on deep space missions. The cost is trivial in the grand scheme of things.
However, I totally agree that it would be crazy not to include one, and whatever it costs, it's well worth it.
I wasn't aware solar was so heavy. Thanks for the info.
Stirling RTGs sound very interesting but I'd be really worried about reliability. Definitely needs lots of work and testing to be confident in it!
It's not similar to a cell phone camera at all. Cell phone cameras are usually much higher resolution (current iPhone is 8 megapixels vs the 2 for Juno), but with a much smaller sensor (iPhone cam has a 1.5µm pixel size vs 7.4µm for Juno).
[1] On average.
Yes.
> Is it on a launch docket?
Yes.
> Is there a rocket ready for it?
It's being built right now, the test is in December.
> Is the lander completed?
It's being built right now, the test is soon.
> 2018 is right around the corner and frankly I'm getting sick of "Spacex might" comments.
SpaceX has completed every single thing they have ever said they would do, except for things that remain in the future. I don't know how you could be sick of "SpaceX might" because it generally means "SpaceX will".
> I'd like to see more "do" from SpaceX that isn't LEO flights and landing on barges.
They're planning on colonizing Mars by sending 80,000 people per year until there are millions living on Mars. They have been working steadily towards that goal for 15 years. They are extremely busy and making the most rapid progress in spaceflight since the beginning of spaceflight itself. Take a step back and realize how much SpaceX is actually doing. If this isn't enough "do" for you, then I think nothing in the world or anywhere in the solar system would satisfy whatever you're looking for.
SpaceX is impressive, but I think its fandom is out of control. Repeating marketing and PR pieces to me isn't convincing. I wish them the best of luck but a 2018 launch isn't happening. I'd be surprised if any of this happens before 2022-2025.
The September announcement at the International Astronautical Congress will be their full proposal for sending humans to Mars, including BFR, MCT, ISRU, the whole works.
For more info, check out the SpaceX forum on Reddit. I know Reddit has a reputation, but the SpaceX fans run a top-notch community there.
td;dr Juno has a fine sensor and lens
You can go buy a camera with the same sensor if you'd like, but they're expensive:
http://www.qsimaging.com/620-overview.html
I believe it's the same sensor that flew on the Curiosity mission and we all know those photos are fantastic. They are also flight tested, invaluable for missions like this where you only get one shot at it.
You also seem to feel the need to defend Juno, as if I was attacking it somehow, so I don't think this conversation can be very productive.
But, as you have made clear, you were just making a statement about the combination of wide field-of-view (i.e., the optics) and the number of pixels, which both figure in to resolution. (By contrast with the New Horizons LORRI instrument, which had a very narrow FOV, because they did not approach Pluto closely.)
If one takes a breath and re-reads what you wrote, this meaning is evident. On the other hand, it's very easy to mis-interpret what you wrote.
Because sensor size is what's important in digital photography, you can always stitch together multiple images to get more resolution. A large sensor like what's flying on Juno is orders of magnitude better than a camera phone sensor regardless of the resolution. In general cell phone cameras (which you decided to compare Juno's to) are high resolution, but with small a sensor (everything in a phone is small!). Juno is the opposite, low resolution and a large sensor. If you want to take pictures of stuff in space you most certainly want a large sensor.
> You also seem to feel the need to defend Juno, as if I was attacking it somehow, so I don't think this conversation can be very productive.
Well you did attack it by saying its camera was the same quality as a camera phone (aka cheap and shitty). It's not similar to a camera phone whatsoever, you were just plain wrong.