from the this-is-no-Mickey-Mouse-operation dept.
Emily Lakdawalla's blog on The Planetary Society has an article on the details of communicating with New Horizons.
Pluto is far away—very far away, more than 30 times Earth's distance from the Sun — so New Horizons' radio signal is weak. Weak signal means low data rates: at the moment, New Horizons can transmit at most 1 kilobit per second. (Note that spacecraft communications are typically measured in bits, not bytes; 1 kilobit is only 125 bytes.) Even at these low data rates, only the Deep Space Network's very largest, 70-meter dishes can detect New Horizons' faint signal.
The article goes into some of the tricks used to improve the data rates and keep within the spacecraft power budgets.
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Just last week we talked about getting data back from Pluto from the New Horizons spacecraft.
Today NASA's "Dawn" spacecraft has returned the sharpest-ever photos of Ceres, just a month before its planned orbit around the mysterious dwarf planet.
On the night of March 5, Dawn will become the first spacecraft ever to orbit Ceres. Its the second solar system body (beyond Earth) that the Dawn space craft has orbited. (Dawn orbited the protoplanet Vesta, the asteroid belt's second-largest denizen, from July 2011 through September 2012.)
Space.com has a story and an animation built of multiple stills taken last Wednesday from 90,000 miles (145,000 kilometers) away from Ceres.
According to Dawn mission director and chief engineer Marc Rayman:
Despite Ceres' proximity (relative to other dwarf planets such as Pluto and Eris, anyway), scientists don't know much about the rocky world. But they think it contains a great deal of water, mostly in the form of ice. Indeed, Ceres may be about 30 percent water by mass.
Ceres could even harbor lakes or oceans of liquid water beneath its frigid surface. Furthermore, in early 2014, researchers analyzing data gathered by Europe's Herschel Space Observatory announced that they had spotted a tiny plume of water vapor emanating from Ceres. The detection raised the possibility that internal heat drives cryovolcanism on the dwarf planet, as it does on Saturn's moon's Enceladus. (It's also possible that the "geyser" was caused by a meteorite impact, which exposed subsurface ice that quickly sublimated into space, researchers said).
Its going to be an interesting couple months for space watchers.
(Score: 5, Informative) by ah.clem on Tuesday February 03 2015, @06:10AM
"...only the Deep Space Network's very largest, 70-meter dishes can detect New Horizons' faint signal."
The DSN is set up so that coverage is always available if they can get the bandwidth reserved; the dishes are spread out 120* around the world (California, Spain and Australia). An interesting side note is that all the 70 meter dishes in the DSN are being replaced with a local network of 4, 34 meter dishes that will all support X-band uplink and X and Ka-band downlink. The proposed date for the completed conversion is 2025. Folks, we truly do live in the future.
(Score: 2) by MichaelDavidCrawford on Tuesday February 03 2015, @10:21AM
I hope they don't just scrap them; they'd make great radio telescopes.
Yes I Have No Bananas. [gofundme.com]
(Score: 1, Funny) by Anonymous Coward on Tuesday February 03 2015, @12:35PM
Radio telescopes? Yeah sure, but how about a parabolic solar death ray instead? Much more fun...
(Score: 2) by ah.clem on Tuesday February 03 2015, @05:01PM
Sweet! That way, when Cleolanta of Ophiuchus or Ming the Merciless of Mongo show up trying to move in on our prime lunar real estate, we can just push the button and "Poof!". Rocky Jones and Flash Gordon can sleep in.
(Score: 5, Funny) by aristarchus on Tuesday February 03 2015, @07:33AM
I am assuming that we only have one post on this Fine Article because of the lag time out to Pluto? Does Pluto have veto power over our comments here? Not that there is anything wrong with that.
(Score: 4, Informative) by frojack on Tuesday February 03 2015, @09:17AM
Personally I've not felt competent to comment on anything Emily Lakdawalla writes.
The Wiki Page [wikipedia.org] has a great deal of info on this spacecraft, including the fact that its launch had the anti-nuclear crowd marching up up and down carrying signs back in 1997.
No, you are mistaken. I've always had this sig.
(Score: 2) by mcgrew on Tuesday February 03 2015, @06:25PM
Pluto is currently four light hours away. Of course, the distance varies because of orbits.
It is a disgrace that the richest nation in the world has hunger and homelessness.
(Score: 2) by Adamsjas on Tuesday February 03 2015, @10:27PM
Well a Collimated beam, of radio or light, might still spread a little, but not to the point we couldn't receive it. There probably isn't much matter to absorb the beam out there in space.
The problem here seems to be the power budget, and storage, and barely adequate transmitters. None of these were adequate to the task of simultaneously snapping photos, and continuous transmission of data.
(Score: 4, Funny) by Anonymous Coward on Tuesday February 03 2015, @09:21AM
Given that the first phone modems had a rate of just 300 bits per second, 1kbps is already more than three times the data rate of the earliest modems.
But I have to admit, sending images at such a data rate sucks. Maybe they should ask New Horizons to just describe what it sees; for texts, 1kbps is plentiful. ;-)
(Score: 3, Interesting) by sudo rm -rf on Tuesday February 03 2015, @10:52AM
for texts, 1kbps is plentiful
Now when I think of it, this is brilliant! Given all those auto-tagging algorithms and image analysis software this might actually work. On the other hand, New Horizons could also start sending ASCII art...
(Score: 2) by DeathMonkey on Tuesday February 03 2015, @06:19PM
Now when I think of it, this is brilliant! Given all those auto-tagging algorithms and image analysis software this might actually work. On the other hand, New Horizons could also start sending ASCII art...
I say we develope a clever algorithim to encode image data so that it can be sent via your text messaging service. We should call it UUEncode.
(Score: 2) by sudo rm -rf on Wednesday February 04 2015, @09:20AM
Hell, I think we're starting to write history here :)
(Score: 3, Interesting) by bootsy on Tuesday February 03 2015, @01:35PM
I saw Vint Cert give a talk about this a few years ago as the USI conference in Paris.
http://www.wired.co.uk/news/archive/2009-11/06/google-unveils-protocol-for-an-interplanetary-internet.aspx [wired.co.uk]
Sounds like it would come in useful here if they are not using something similar already.
(Score: 0) by Anonymous Coward on Tuesday February 03 2015, @03:06PM
(Note that spacecraft communications are typically measured in bits, not bytes; 1 kilobit is only 125 bytes.)
as is every "broadband" internet speed in this part of the universe :)))
(Score: 2) by tibman on Tuesday February 03 2015, @08:06PM
Which is funny because all content is measured in bytes, not bits.
SN won't survive on lurkers alone. Write comments.
(Score: 1, Insightful) by Anonymous Coward on Wednesday February 04 2015, @05:11PM
I think it's because originally, the number of bits per second was the same as the baud value, which again is directly related to the physical frequency. That may also be the reason why it had always been measured with proper SI prefixes, even at a time when storage capacities were consistently measured in units of 1024.