Prototype Telescopes Complete Key Test

Matthew Sparkes writes "Two prototype antennas for the world's largest array of millimeter-wave telescopes have passed a key test, working to track and image Saturn for more than an hour. Ultimately, ALMA (Atacama Large Millimeter/submillimeter Array) is expected to resolve details 10 times finer than the Hubble Space Telescope when it is completed in 2012."

Hubble censored? Data encrypted?

[Firethorn]

I have no problems believing that the control data is encrypted for the hubble. For one thing, you don't want others taking it over.

As for the data, I'd imagine that it'd be compressed, encoded, and multiplexed to the point that you'd need special equipment that no normal HAM operator* would have, much less the settings needed to sort it all out and make sense of it.

For public key stuff - that's more computationally intense than private key military encryption methods. Remember, we're talking about systems where a 386 would be considered 'high end'.

*I'm not saying that you're a 'normal' Ham operator, Crawler, but we're talking the space industry here.

Apples and oranges

[$RANDOMLUSER]

Ultimately, ALMA (Atacama Large Millimeter/submillimeter Array) is expected to resolve details 10 times finer than the Hubble Space Telescope when it is completed in 2012.

Except that one is a radio telescope and one is an optical telescope.

Re:the use of space-telescopes?

[Falladir]

The people who design and build these telescopes don't have unlimited budgets. If they use up their grant money sending a telescope into space, they can't hire as many graduate students, for instance. While saving money isn't the primary concern for the principal investigator, it's certainly a priority.

The reason WMAP was a space telescope was, as you said, so that it wouldn't have to look through the water-vapor in the atmosphere. ACT [princeton.edu] and ALMA will be earth-based because it's impractical to send telescopes as big as those into space.

In summation, don't worry: astronomy funds are not being wasted!

Re:the use of space-telescopes?

[Tablizer]

I'm actually beginning to wonder if space-telescopes still have their use

It is hard to separate hype from reality. Hubble is used as the benchmark in many claims because of its popularity. But as you partially pointed out, there are some rough-spots in Earth-based techniques:

* Spectrum coverage: some important frequencies are blocked by the atmosphere.
* Ecology: Earth scopes are accused of messing up mountain peaks and views and "sacred lands".
* Guide-stars: Some earth-bound techniques require bright guide-stars near a scene to compensate for atmospheric distortion. This limits their use in dim portions of the sky.
* Southern hemisphere: It is hard to see all portions of the sky well from any given point on Earth.
* Newness: Many of the hi-res earth-scope techniques are new and complicated. Without a reference point, such as Hubble images, they may be collecting unintended artifacts of the technology.

But it is an interesting issue to consider.
       

Re:the use of space-telescopes?

[Gil-galad55]

Land-based telescopes are gaining much ground, especially when it comes to data volume. The dataset for the LSST (Large Synoptic Survey Telescope) will most likely be measured in exabytes when all is said and done, and it simply isn't possible to send that volume of data home via telemetry. However, space-based telescopes most definitely have their place.

Two exciting ones are Planck, which will make extremely precise measurements of the CMB (Cosmic Microwave Background) and--if we're lucky--LISA, a gravity wave telescope that will open a completely new part of the universe to us. The science prospects for LISA are staggering, and it is simply impossible to build an interferometer with a 5 million km arm length on the ground!

Re:the use of space-telescopes?

[thrawn_aj]

You forget light pollution, which is a major problem for ground-based telescopes. That's precisely why LISA and LIGO can work on the ground - they're not measuring light, they're trying to measure gravity waves, which (we hope) are strong enough to show up in the interferometer. Space is better for another important reason, especially for new telescopes: it is VERY cold in space (~2.7K). This means you can use superconducting wires with impunity and without the need for a coolant. That itself should be a significant advantage. I do hope they make use of this =D.

Re:More embargo than censorship.

[Teun]

It seems you forget that your tax money bought more than just the Hubble Telescope, the deal includes the scientific institutions that add value to the raw data.
Many of these institutions bring their own budget and they want Value for Money, they need, for a period of time, to have some exclusive access.

I'm sure that when you bring a juicy enough budget and the credentials for high-level research you can have a set of keys to decrypt the data first hand.

Re:Hubble censored? Data encrypted?

[Firethorn]

Hmm... My extent of satellite experience was working with 8" floppies and multiplexors at Schriever AFB years ago, and more recently training in how to configure slightly more modern multiplexors for field applications. Fun time: spending three hours troubleshooting while in chem gear only to have the instructors realize that their satellite simulator(couldn't get real sat time for the exercise) had been jarred out of position.

No, of course you dont want some random joe to take Hubble over. However, they could implement in which "packets" are signed. The data would be separate from the authenticated signature. Along with that, they would want to implement a proper timecode to prevent replay attacks.

I've learned that satellites tend to keep their control and data bands seperate, and the usage of multiplexing* is common, especially when you're talking about multiple instruments. And our demuxers run in the hundreds of thousands of dollars for our stuff, much less NASA science stuff. Remember what I said about military private-key encryption being cheaper computationally? Timing is already part of the security, and the hubble was designed back in the '80s and would have to use a system cleared for space and capable of remaining secure through decades of operation. Public key infrastructure is too new, computationally expensive, and expaning of a field. After that, it's easier to encrypt the whole channel than to worry about packets.

Are you even sure that you were trying to listen in on a data channel? From my reading it looks like the hubble stores it's data and then transmits it down in batches.

*For the uninitiated, a multiplexor takes multiple data streams and merges it into one stream, which a demultiplexor then splits back into multiple streams. For example, something like 60 voice lines, two ip networks, a crash-net(think red phone), etc... I'm sure Creepy Crawler knows this, but other readers might not