[cornholio]

I understand JunoCam is a public outreach tool. But if it provides much worse resolution than Hubble from inside Jupiter's orbit, it's basically useless even for that. I don't know if the cam is the problem or the transmission bandwidth, one thing is clear, when serios science starts there will be much less bandwidth available to send sharp and cool photos.

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 !

[drzaiusapelord]

>gotten in their minds that RTG power is evil and dangerous

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.

[mikeash]

Juno is the first use of solar panels for a probe going that far out. You're right that they want to err on the side of caution using well-known technology to minimize risk. But you're missing the fact that RTGs are that well-known risk-minimized technology.

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.

[drzaiusapelord]

I was referring to the new stirling engine RTG. According to wikipedia, NASA doesn't see it being used in a mission for another decade or two due to further testing and certification.

I wasn't aware solar was so heavy. Thanks for the info.

[mikeash]

Inverse square is a harsh mistress. With only 4% the insolation at Jupiter as you get at Earth, you need a lot of panels.

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!

[tdy721]

bitrate it uses is good enough for the mission

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.

[drzaiusapelord]

Well, Curiosity is huge and at that point needed a power source that wasn't solar. I really am not buying that these are political decisions. I think there's more emphasis on solar and less RTG in some scenarios because everyone is worried about the plutonium situation. No use wasting plutonium on missions that frankly just don't need it.

[dredmorbius]

The probe is 2.7 million miles from Jupiter, headed further out (its orbit is highly eccentric). That's nearly 11 times the distance from the Earth to the Moon.

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.

[mikeash]

Strictly speaking, the probe will be spending most of its time at distances like these. That's the nature of elliptical orbits. But it'll spend enough time up close to get some great pictures.

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.

[drzaiusapelord]

>But NASA likes pretty pictures too, so they included one.

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.

[mikeash]

I don't know that the cost is trivial. The camera is cheap, sure, but that's weight and power and bandwidth that could be spent on something else.

However, I totally agree that it would be crazy not to include one, and whatever it costs, it's well worth it.

[dredmorbius]

Much != most.

[nacnud]

Juno is in a highly elliptical orbit, which will take it within 5000km of Jupiter's cloud tops. This photo was taken from much further away than that. In short, check back in about a month. :)

[azernik]

Agreed, and to add more detail for comparison - the current distance is around 2 million kilometers, so resolution should jump by a factor of about 500 (per dimension, not number of pixels) at closest range.

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

[2] http://www.spacetelescope.org/images/heic0910q/

[jessriedel]

Current distance is 2.7 million miles, or 4.3 million km, according to the NY Times caption.

[mikeash]

Juno's solar panels produce as much power at Jupiter as Galileo's RTGs did. The quality of this picture has nothing to do with solar power. It's a bad picture because Juno is on a highly elliptical orbit for reasons of efficiency and longevity (there's tons of radiation closer in) and this picture was taken when the probe was very far away.