MRO RADIO RECEPTION

[slidelock]

Just wondering, since Nasa is rather infamous about releasing data belatedly, re: deep impact, I was wondering if it would be possible to receive the incoming signal privately?I have begun to get into Ham in a big way, so I thought about placing a ground loop around my house if necessary. Anyone know the required freqs etc?

 

[kane007]

Did a google and came across <i>The MRO transmits on DSN channel 32 which is 8439.444444 MHz - by the time that reaches Earth, due to Doppler the frequency has dropped to around 8439.031 MHz.</i> but I believe the signal may be encoded.

 

[mikejz]

Some individuals have managege to recieve deep space probe's transmissions. In all cases it was just a carrier signal, no data. The get data would require a lot of work in terms of demodulating, data format, etc. <br /><br />If you want to work on detecting there carrieers, I would first look at getting a second-hard C/Ku satellite dish, the larger the better.

 

[slidelock]

Encoded? Why would you encode a scientific transmission? Why dont they release incoming data in real time? I cannot imagine a better incentive for the black helicopter conspiracy theorists. Thanks for the freq. tho.

 

[CalliArcale]

The main reason would be to compress it. There are lots of clever tricks for squeezing more out your bandwidth, but the end result is that receiving and understanding the signal requires technical details about the signal.<br /><br />There are people who have successfully received the carrier signals of deep space probes. However, it's the barest limit of their technical capabilities to do that; actually getting telemetry or pictures requires expensive equipment. The main limiting factor is the size of your reflector dish; DSN antennas have enormous dishes costing millions of dollars to collect and focus the faint signal. But that's not to say it's impossible for a hobbyist to receive a deep space signal. You can pretty much forget about receiving Cassini's signal, but the inner solar system probes may be more accessible, especially when they're relatively near to Earth. (For Mars probes, that means your best bet for receiving the signal is near the time of opposition, when Mars comes the closest to Earth.)<br /><br />Here's a link to a group of amateurs tracking Mars Reconnaisance Orbiter. (They've also tracked Venus Express.) The last reported reception was in January; I have no idea how up-to-date they keep their page, but they're soliciting hardware for building a DSN receiver, so these are people you might want to contact if you're thinking about doing the same sort of thing. They know the technical details, and being hobbyists, they're probably very willing to share.<br /><br />UFO Satcom: Mars Reconnaissance Orbiter Monitoring <br /><br />EDIT: In particular, follow their link to the Yahoo! group they've created for discussion of amateur reception of DSN signals. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[CalliArcale]

Additionally, don't confuse "encoded" with "encrypted". Unless you're into signals and computer science, you may think they're the same thing, but they're not. Everything sent digitally is encoded. Encoding is the process of turning the information into a series of 1s and 0s which can be transmitted to a receiver, where they can then be decoded into something useful. For a very simple example, this post, written in English, will be encoded using a code called ASCII, a standard for representing characters (letters and digits) as numbers, which can then be represented in binary, which in turn can be transmitted across the Internet. When it gets to your PC, your computer takes those 1s and 0s, decodes them into characters, and then draws those characters onto your monitor. The letter "A" is never sent across the Internet -- instead, the number 65 is sent, which in binary is 1000001. So when the computer wants to encode the letter A, that's what it sends.<br /><br />That's a very simple example of encoding, and a well-known, standardized one. A spacecraft such as MRO may not use standard encoding methods; because its mission is very specific and its bandwidth is so intensely valuable because of the rarity of its data, engineers may have devised an entirely unique system of encoding the data which optimizes the bandwidth useage. Odds are, though, they've used a preexisting system, so if you can get a hold of the equipment, it should be at least theoretically possible to pull data out of the stream. I suspect you would not have enough signal strength to do it, though; the dishes normally used to communicate with these probes are very large, much larger than a hobbyist could afford.<br /><br />Encrypting, on the other hand, is the process of garbling the data in a very specific way so that it is useless to a third party intercepting the signal. A key of some sort is provided so that the recipient can then decrypt the signal and make use of it. Encryption can be use <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[rocketman5000]

couldn't an array of smaller dishes be able to receive the signal. Something like the Google radio network? A number of smaller dishes might be affordable to the hobbist, although it would take a fair amount of land to erect them.

 

[mikejz]

Its not that simple to combind the signals in the array

 

[rybanis]

Martin Sheen did that in the crappy Sci-Fi movie, "The Arrival".<br /><br /><br />Yes, you would get more signal (more dishes=more surface area), but it would be very tricky combining the feeds from several dishes. <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>couldn't an array of smaller dishes be able to receive the signal.<p><hr /></p></p></blockquote><br /><br />Yes. For instance, the Very Large Array in Socorro, New Mexico uses exactly this concept to effectively acheive much larger apeture than any single-dish radio telescope (bigger even than Areceibo). It's not set up to receive DSN signals, but it could be adapted. (Areceibo has been adapted to receive DSN signals, incidentally. The very last Pioneer 10 signals were received by that mammoth dish, the only one on the DSN capable of communicating with Pioneer 10 at the end. No other had sufficient aperture.)<br /><br />It requires a lot of hardware, though, and in particular you'll need to duplicate a lot of DSN equipment between all of the antennas. It also requires a lot of computer work, so it would require more technical skill than using a single dish. I wouldn't put it beyond the realm of possibility for amateurs, though. There are some extremely skilled hobbyists. In theory, if three or four have set up the neccesary equipment, they could join forces and get a better shared signal than any could indepedently. It's not trivial, by any means, but I could see it being done. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[rybanis]

I seem to remember hearing of an array in northern california made entirely up of commerical gear...if I wasn't writing a term-paper right now, I'd look up the link.. <div class="Discussion_UserSignature"> </div>

 

[chriscdc]

Is there any legal reason as to why Nasa can't give out the information on the compression algorithm?<br />Perhaps by the time the MRO goes up it will be possible for a person to set up a recieving station? Do you reckon that using a 2009 computer it would be possible to use the many dish technique?

 

[rybanis]

If you had the budget to accomplish such a thing, you could receive the telemetry. You'd just have to know when downlinking was going to happen. This would also have to happen when mars was in your sky. Nasa DSN is all over the world, so they could be receving during a time when your orientiation was wrong.<br /><br />For your other question, I think the scientists would be a bit hesitant to let a person do that, as they would like to have first dibs on the science, so they can publish findings on their work. <div class="Discussion_UserSignature"> </div>

 

[mikejz]

I would recommend reading up on Amsat P-5a <br /><br />http://www.amsat-dl.org/p5a/<br /><br />Its a ham radio/amature satellite mission that is being planned for Mars, including ground tracking.

 

[chebby]

What about sending the signal to the probe? Do you need a huge dish to send the signal as well?

 

[mikejz]

I would think not, they could just use brute force for the transmitter.

 

[chebby]

I always though that if someone snooped on the earth-proble communications, then in theory, one could take over control of that probe? <br /><br />Imagine, someone taking control of the mars rovers, changes something so that they no longer accept incoming communications without a secret code, and demands ransom? <img src="/images/icons/smile.gif" />

 

[kane007]

Then I'd think some one would just cruise missile their antenna array.

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>Is there any legal reason as to why Nasa can't give out the information on the compression algorithm?<p><hr /></p></p></blockquote><br /><br />If they used something proprietary from a supplier, they wouldn't be allowed to disclose it. That's unlikely, though. However, it is possible for the compression algorithm to be something restricted under ITAR. ITAR stands for International Traffic in Arms Regulation. Some computer programs (particularly compression and encryption algorithms) cannot be exported without permission from the government to prevent potentially hostile foreign powers from gaining the technical expertise. That wouldn't preclude them releasing it to the public, but it would definitely preclude them from putting it on the Internet.<br /><br />Mind you, I don't think the algorithm is likely to be ITAR-restricted. I'm just speculating on various possibilities.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Perhaps by the time the MRO goes up it will be possible for a person to set up a recieving station? Do you reckon that using a 2009 computer it would be possible to use the many dish technique?<p><hr /></p></p></blockquote><br /><br />MRO is already at Mars. <img src="/images/icons/wink.gif" /><br /><br />You could use the many-dish technique with computers available today. Technologically speaking, it is acheivable for amateurs. But they have to really know what they're doing. That's the hard part (along with actually building enough DSN receivers; some of the parts are apparently in short supply). <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[kane007]

The Allen Seti array is an example of this radio interferometry that you have in mind.

 

[rocketman5000]

thanks that was actually the array I was thinking of, I just remembered it was an internet/computer related entity

 

[slidelock]

Excellent technical discussion as always. But it does ignore a smaller or perhaps larger question, as to why NASA treats its data as proprietary when it was in fact paid for with taxpayer dollars. If you can imagine NASA providing their video downlink from any of the MARS missions in real time, then you have a better imagination than I do. What gives?

 

[telfrow]

As soon as raw images are processed, they're posted on the Mars Exploration Rover Site and the Cassini Raw Image Site - usually within twenty four hours or less. <div class="Discussion_UserSignature"> <strong><font color="#3366ff">Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild.</font> - <font color="#3366ff"><em>Tennyson</em></font></strong> </div>

 

[mikejz]

The US has some of the most liberal public document laws in the world. If you wanted them, I bet JPL would let you access the data tapes from Voyager/Apollo/etc. .<br /><br />Of course there are practical limits, mainly with the use of contractors that may incorporate proprietary compression/transmission protocols--But to claim that they are being anything other than forthright is disingenuous.<br /><br />Now if they would just publish the protocol for SunPass I would be set <img src="/images/icons/smile.gif" />

 

[spacechump]

Maybe its because they don't HAVE direct video feeds from ANY of the missions. Images and data are collected onboard the spacecraft and then transmitted to earth when the communication window opens, which is accurately timed by both spacecraft and ground control.<br /><br />For some reason I have this feeling you think spacecraft are always transmitting all the time like a television station. It's much more complex then that.<br /><br />This will help you out:<br /><br />http://www2.jpl.nasa.gov/basics/bsf10-1.html