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Comment by draugadrotten | Hacker News Reader

It will take approx 16 months to transfer all the pictures it took, because it is transmitting at only 1 kbit/second.

http://www.planetary.org/blogs/emily-lakdawalla/2015/0130080...

> because it is transmitting at only 1 kbit/second.

I read elsewhere that it's also because other projects need to use the Deep Space Network, and bandwidth is a little constrained.

This is true. Communicating with New Horizons requires using the 70m DSN dishes. Of which human civilization has built ... 3. So monopolizing that resource for an entire year would be problematic. Instead the probe will send back highly compressed gallery sheets of all the images it has as well as a few pre-selected shots (some of which we've seen) which the science team will use to prioritize the data the gets sent back. Then the highest priority images will be transmitted using loss-less compression and the remainder will get sent over the remaining months off and one when the 70m DSN dishes aren't needed elsewhere.

Maybe its time to build more then. It seems silly to be bottle-necked on things like this.

Lots of missions and mission phases don't require bigger antennas. Look at http://eyes.nasa.gov/dsn/dsn.html for current usage of the Deep Space Network. As I type this, 3 smaller dishes in Goldstone are handling 4 Mars missions, all solar powered, Odyssey at 14.22 kb/s. At Canberra, the only active dish is a small one, receiving data at 159 b/s from Voyager 2 (!). Which, I grant, doesn't have a lot to say right now.

3 sites, 1 big dish and 3 smaller ones at each, except for a 4th smaller one at Goldstone, that's a serious investment and I gather enough for now, especially since satellite technology now allows storing massive amounts of data (8 GB for New Horizons) for download as the mission and ground stations allow. Note also that after New Horizons finishes downloading the data from its flyby in November 2016, it won't have a lot to say unless and until its Kuiper belt object flyby.

Fair enough. I had not realized that NH could send data at a faster rate when bandwidth was available. I wondered about the point of having 8 gb storage when you had such low speeds - it would take years to download.

As for the storage capacity, that's dictated by the amount of science collected. Who cares how long it takes to download?

It's taken 11 years from mission inception for New Horizons to get built, launched, and get to Pluto. What's a year or two more?

Eventually, a lot of spacecraft communications will switch to optical systems instead of using radio. The major gating factor there, at least in regards to solar system exploration, is the creation of off-Earth infrastructure to facilitate it. Which likely would be just a small fleet of relatively modest sized space telescopes designed for 2 way communications. Having the infrastructure off Earth would mean that it would be insensitive to weather and would also be easier to maintain contact with spacecraft nearly anywhere in the sky at any given time. Building that infrastructure probably won't happen until launch costs fall but realistically it's something that could easily happen in the next decade or so.

And then the available bandwidth goes way up.

> monopolizing that resource for an entire year

These dishes all look in different directions, so 2 out of 3 wouldn't even be able to communicate with the probe most of the time.

Sort of, but keep in mind that if another probe is in a similar part of the sky as New Horizons then they will compete for dish time.

Your linked article says 2 weeks, not 16 months.

11 photos a day.

I don't know why that article quotes two weeks. I've read the 16 months figure in several places and it was mentioned in the press briefings yesterday. There might be a specific subset of data that will take two weeks to get. Perhaps the low-res JPGs of all of the planet imagery.

That article says two weeks because it's talking about a different set of images, from January. The uncompressed images from the fly-by will take the roughly 16 months you mentioned, but there will be smaller, compressed images before that.

I think it's 16 months to transfer every piece of sensor and imaging data back. The article says it takes ~40 minutes to transfer back a losslessly compressed full resolution image from the LORRI scanner

Anyone got info on the software/hardware specs and how they approach prioritizing and storage management? We waited a long time for the Apollo code to make it to Github--what better way to rope in the interest of one segment of humanity than getting more eyes on the code?

I imagine that there wasn't time or power to do patches...but if there was, even the mechanics of that would be fascinating.

Has anyone ran across a good discussion around the computational aspects of New Horizons?

http://www.planetary.org/blogs/emily-lakdawalla/2015/0624055...

http://www.planetary.org/blogs/emily-lakdawalla/2015/0130080...

Some basic info on communication. The wikipedia page has a lot of info.

The most important parts are that it has a redundant pair of 8GB flash drives and they actually upgraded the code in-flight to use both transmitters at once and nearly double the data rate.

I'm not sure how priorities are arranged but it's all going to be sent back relatively quickly in terms of mission lifetime, and I think they managed storage use mostly by putting in plenty.

they actually upgraded the code in-flight to use both transmitters at once and nearly double the data rate

It was anticipated this would be possible, depending on how the energy budget for the whole craft worked out.

One of the early things I did when I obtained a computer modem was dial into a NASA BBS and download images of planets taken by Voyager. I believe it was at 300bps, although we may have had our 2400bps modem by then.

Fortunately I didn't spend 16 months at it, since we were paying long distance charges and just a couple of pictures of Neptune downloaded over the course of an hour or so cost a relatively ridiculous amount of money.

Still, it makes me feel a kinship with these folks, even if just barely.

That's the delay in getting a single batch of images back during the approach phase, not how long it'll take to get all of the images from the flyby back.

Reminds me of RealPlayer.

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