Problem with NASA radio signals going to Mars?

[MeteorWayne]

Well the dispersion of the signal is only part of the issue around earth.<br />The ionosphere reflects, refracts and absorbs radio waves, depending on field strength and frequency of the radio waves.<br /><br />We've never gotten a good answer from the original poster exactly what the problem with radio signals going to Mars was, since AFAIK, there aren't any.<br /><br />So perhaps before we speculate, it would be good if that question was answered so we knew what the heck he was looking for!! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[nec208]

Space is not a perfect vaccuum. <br /><br />Actually there's no point in continuing this thread until you educate youself on the propogation of radio signals, which you have stated you refuse to do. <br /><br />If you had the faintest clue, you would know thaere are many places to reflect radio signals including atmospheric and ionisphereic phenomena. <br /><br />---------------------<br /><br />I know space is not a perfect vaccuum you have stars ,planets, gravity, black holes , asteroids and gases.<br /><br />And yes you are re-saying the same thing I was saying in other way !!! Someone who has a CB knows frequencies below 30MHz bounce around the world but not all the time .<br /><br />The sun and solar flares can make the radio signal travel or other times do the opposite.<br /> <div class="Discussion_UserSignature"> </div>

 

[nec208]

We've never gotten a good answer from the original poster exactly what the problem with radio signals going to Mars was, since AFAIK, there aren't any. <br /><br />----------------------------------<br />Have you not watch the news how NASA some times have a hard time communicating to the space probe or satellites on mars if the planet is turned around.<br /><br />That say it this way so you can understand how do you communicate to a space probe be hide the moon? Same thing here.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[MeteorWayne]

So why do you find it hard to understand why it's difficult to communicate with a probe on the other side of a planet or a moon. Radio does not travel well through planets. No great mystery. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[Mee_n_Mac]

<font color="yellow">you should look for position as teacher if you don't teach already</font><br /><br /><br />Hehehe ... I couldn't afford the pay cut. <img src="/images/icons/smile.gif" /> Besides I'm told (by the OP) us engineers get lots of vacation time so I figure I'll keep my day job until I see some of that. <img src="/images/icons/wink.gif" /><br /><br /><br />Honestly, it's very hard to figure out what nec is asking for in his/her posts. I'm not sure if it's a language barrier or ???? and often his replies come back on the rude side of acceptable. But someone mentioned nec is a 14 yr old kid so I'm trying to view his posts in that light. <div class="Discussion_UserSignature"> <p>-----------------------------------------------------</p><p><font color="#ff0000">Ask not what your Forum Software can do do on you,</font></p><p><font color="#ff0000">Ask it to, please for the love of all that's Holy, <strong>STOP</strong> !</font></p> </div>

 

[nexium]

This must of been a bad day for MeteorWayne. I appologize on his behalf. In space radio signals attenuate as the square of the distance. ie if your antenna produces one milliwatt per square foot at a distance of one mile it will produce 1/4 milliwatt at a distance of 2 miles. At one thousand miles the signanl is one nanowatt per square foot which is one million times less than the power at one mile. The power is not really lost, it is just spead over a much larger area. Light and Xrays and gamma rays weaken by the same ratio in space.<br />On and near Earth's surface (or moon or planet) signal loss is often the cube or 4th power of the distance, but occasionally the ionized layer acts like a giant magnifying mirror and a strong signal is received hundreds or even thousands of miles away. At low sunspot activity such as now, long distant signals occur most often on the high half of the medium wave (MF) band and most of the high frequency (HF) band. From about one million hertz to about 25 million hertz. During the peak of sunspot activity, the magnification occasionally occurs as high as 100 million hertz, which is half way into the very high frequency VHF band. Neil

 

[MeteorWayne]

I don't understand why you said I had a bad day.<br />The poster indicated he had no understanding of the propogation of radio signals, and specifically stated he had no desire to learn about them!<br /><br />He was talking about atmospheric effects, when ionospheric effects are most important for the frequencies mentioned.<br /><br />We all know about the dissapation of signals by the increasing area covered.<br /><br />I still don't understand where the mystery was about communicating with probes on Mars. Nothing about communicating with Mars is an unexpected problem.<br /><br />That's all I was saying.<br /><br />MW <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[dragon04]

Maybe he doesn't remember the days when TV feeds would be lost as communications satellites orbited the Earth.<br /><br />Loss of radio contact with probes happens all the time if he thinks about it. And probe that is inserted into an orbit goes "behind" the planet and the mission team doesn't know if the target planet captured the probe until they get telemetry back after the probe reappears from behind it.<br /><br />But it's not a "problem" per se. One of these days, we'll probably have enough comm birds in Martian geosynchronous orbit so that global communications is possible.<br /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[nec208]

This must of been a bad day for MeteorWayne. I appologize on his behalf. In space radio signals attenuate as the square of the distance. ie <br /><br />=====================================<br /><br />Matter attenuates a vacuum cannot.<br /><br />A planet,stars,gravity or gases attenuate. Remove the planet,stars,gravity or gases you just have empty black space and there be no way to calculate how big space is because to calculate you need a reference point.<br /> <div class="Discussion_UserSignature"> </div>

 

[nec208]

Maybe he doesn't remember the days when TV feeds would be lost as communications satellites orbited the Earth. <br />__________________________<br /><br />I use cable for TV and internet .<br /><br />But everyone even at age 16 or girls know this basic law!!.<br /><br />A radio signal becomes very weak underground , under a bridge, in a valley,by tall buildings, by hill and this just some of the laws .<br /><br />Cementite and steel is also bad for radio signal .<br /> <div class="Discussion_UserSignature"> </div>

 

[nec208]

But it's not a "problem" per se. One of these days, we'll probably have enough comm birds in Martian geosynchronous orbit so that global communications is possible. <br />----------------<br /><br />You mean a big radio network? <div class="Discussion_UserSignature"> </div>

 

[dragon04]

<font color="yellow">You mean a big radio network?</font><br /><br />More or less. It's not a "problem" to send and receive signals to and from Mars. We've been doing THAT since (IIRC) 1964 when the first Mariner probe did a fly by of Mars and transmitted pictures back to Earth.<br /><br />The only "problem" we have in regards to Mars today is that we don't have a network of satellites in geosynchronous orbit that will be able to cover the entire surface of the planet. So, it's possible for transmitters on the ground to have blackout periods.<br /><br />Despite the Earth's atmosphere, we have downlinks all over this planet capable of receiving transmissions from mars at all times of every day. Unless Earth is hit with a solar flare. Then I don't know if we can or can't receive signals from Mars in that case. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[nimbus]

That might've been me. I remember reading nec himself mention or imply that he was 14 years old, but with a quick search, the closest such reference I found was this.<br />Reading his posts I sometimes got the impression that there is more than one kid using the account. <div class="Discussion_UserSignature"> </div>

 

[nec208]

You misunderstood me, I was saying my science is at very basic elementary school level.<br /><br />That is why I don't know some of those things .<br /> <div class="Discussion_UserSignature"> </div>

 

[nec208]

And yes I don't know much about gravity and yes I'm rading all the forms to understand gravity.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[unclefred]

If you think there is a problem with Mars radio signals (and there isn't) consider this: Last week (August 5 to be exact) the MRO spacecraft increased its data rate to 6 Mbps. Many people are happy with their DSL link at home. We have the equivalent of 4 DSL links to Mars. Since the science phase started, MRO has sent down 22.2 Terabits of data. There is no communication problem.

 

[nec208]

But they can use radio waves for data and pictures too.<br /><br />So they use more radio spectrums for sending more data.<br /> <div class="Discussion_UserSignature"> </div>

 

[jgreimer]

About 15 years ago I was designing analog base stations for cell phones. Around that time one of the engineers saw an article in the paper that mentioned the minute amount of power NASA was able to pick up from a interplanetary probe. As I recall the figure was about 1 femtowatt or 10^-15 watts. We were curious how that figure compared that of our receivers. It turned out that our receivers also could detect a femtowatt. The difference wasn't in the receiver but in the antenna. A radio telescope dish can concentrate power from a huge area in order to get that femtowatt.

 

[nec208]

I was reading NASA uses very low power for transmitting and receiving and the antenna SETI uses is very big and around it takes big radio wave and concentrate the radio wave in the center.How it does this I do not know.<br /><br />Also vacuum cannot attenuate the signal.Now I forgot the basic law on line of site I for got what that law is.<br /> <div class="Discussion_UserSignature"> </div>