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Phoning Home: Communicating from Mars

Music. Narrator: After seven dramatic minutes of entry, descent and landing, everyone will want to know: did Curiosity survive? There’s a possibility we won’t know. At least not right away. During its descent through the atmosphere, Curiosity must switch to a new antenna for each transformation it makes. At each switch, we could lose lock on the signal for a short time. That won’t hurt the rover. It just means we won’t know what’s happening right away. Even with a solid signal, the communications link direct to Earth only works during the first half of the rover’s descent. Why? Like Earth, Mars is spinning — and during landing Curiosity and its landing site will disappear from view, like the sun setting. Out of sight equals the end of direct radio contact. But… NASA has two spacecraft orbiting Mars that can help. For the second half of Curiosity’s descent, the Mars Odyssey orbiter is in a good place to pick up the rover’s signal and send it right back to Earth. To best hear Curiosity’s signal, Odyssey must rotate about an hour before landing. That sounds easy, but engineers are asking Odyssey to perform a maneuver it’s never tried before. Will it work? Probably. But it’s not a sure thing. If Odyssey doesn’t rotate successfully, never fear! The rover won’t be affected whatsoever! Once again, it just means we have to wait longer to hear from the rover. Odyssey could perform as hoped, but we’re still not home free! Engineers always think of ‘what ifs.’ For instance, what if the rover lands on a slope? If so, the low-flying Odyssey orbiter might not be able to pick up its signal. Even if everything goes according to plan with Odyssey, there’s a final challenge: time. The rover may be standing safe on Mars, but Odyssey has to be quick in getting the signal. Odyssey is moving fast. It will only be in the line of sight to hear from the rover for a few minutes — perhaps no more than five. So the Mars Reconnaissance Orbiter plays the role of backup. It will also fly overhead to capture what happens and then store the landing data it collects onboard, for playback to Earth a few hours later. Engineers then have to decode the data, which takes several hours. Sometime in the middle of the night for Curiosity’s mission team, it’s possible that the orbiter could tell us the rover’s fate. Or, there are other scenarios where the rover might be perfectly safe, but we might not hear from it for three days. That’s all to say: Curiosity’s landing is filled with drama and we’ll need lots of patience. No wonder they call this ‘rocket science.’ Music.

100 Replies to “Phoning Home: Communicating from Mars”

  • If you're not impressed by NASAs ability to figure out how to do all this crazy shit, you're a sad case.

  • و الله خسائر فلوس و بس، أناس مغفلين يريدون إثبات وجود حياة خارج كوكب الأرض، لكن نحن المسلمين الله أخبرنا في القرآن بإنه لا يوجد حياة الا في كوكب الأرض فقط

  • congrats to JPL and everyone who participated! I was more and more excited as this day was comming, and am unbelievably glad that everything went flawless. But please someone who watched it tell me please, due to being from europe i overslept live stream, was it streamed from headquarters here on earth, or there was camera on rover?

  • *face palms*
    Why there's no public feed from a true color camera?! A tiny cell phone would do.
    Why the signal needs to be encoded?! And why it takes several hours to decode it?! Don't you have the description key?!
    Also it was never explained why the rover would go mute for days…
    And why this presentation seems like is directed to children?!

  • I was not referring to the modulation of the signal but whether it is encrypted or not.
    What kind of modulation would take hours to process? Must have a horrible bandwidth and a huge error control. Specially for a one way feed for example. I presume the transmission power of the satellites must be pretty weak. Can you tell us what is the power and modulation in use?

  • Well it is encrypted. The modulation isn't the object being processed for hours, it is the data being received from the rover that is encrypted. In addition the rover is constantly gathering data(even if we don't know if it has landed or not), it also takes time for the data to travel and be processed.

  • Well that is my point, I could see the scientific data being encrypted but a video feed could very well be public, which doesn't even exist. All the information coming from the rover is preprocessed before we can get it. Not a lot of transparency.

  • Probably with a big spinning counterweight or something, satellites use those to make small adjustments.

  • Judging from your name calling you must be a very smart person. Smart enough not to even watch the video and know that when the rover is below the horizon its signal is relayed to satellites. Very smart, says a lot about you.
    Also your conclusion that me asking questions makes me a "conspiracy nut" is very interesting. Bravo! I see that there is no such thing as a "conspiracy" (probably not even a real word) and that the government never lies or hides things. You must be from another planet!

  • You don't even have to mention the word "conspiracy". I've seen a lot of people like you and know what you're up to before you even admit it. You probably believe the moon landing was fake also.

  • It uses three devices known as "momentum wheels", which are heavy rotating discs inside the spacecraft that employ the physics principle known as "conservation of angular momentum" to impart rotation on the spacecraft.

    Engineers were a bit concerned because one of the three wheels stopped working when they tried to use it 6 weeks ago (consider Odyssey has been orbiting Mars for 10 years now), but luckily the backup wheel did the trick.

  • There's something I dont understand completly yet: the whole landing was a programmed operation, right? I mean, if the signals from here takes about 5 to 20 minutes to get there, there's no way of control the rover in real time, or I'm wrong? And after that, how is the exploration on the surface? it has just a long "delay" until the rover answer the commands from Earth? Thanks!

  • While the antenna on the rover requires aid from the satellites, here on Earth we can send a powerful enough signal to reach the rover directly. Granted like everything radio waves must adhere to the laws of physics, so it cannot surpass light speed, (186,000 miles a second) but the delay would never be longer than a few minutes.

  • In terms of exploration after landing the commands are more "go here" or "perform test X on sample." Which to my knowledge is how the last 2 rovers were controlled most of the time.

  • Yeah, JPL is pretty good about their software control processes, from what I've read. Definitely once it happened they immediately added a cycle into their software test routines.

  • Yeah, pretty much. For more complicated manuvers they test it with a copy of curiosity on earth before sending the command. There is no real time control

  • Learning about Mars helps us learn about ourselves. If Mars used to be able to support life, there's the possibility that life did once exist there. If life did exist on Mars, the odds that we are alone in the universe decrease dramatically. Just one of thousands of things to be discovered on Mars.

  • There is some theory, but only theory. Curiosity has an equipment to measure the radiation level. What more, there is some craters on Mars, that some astronomers say are unnatural but was made by bomb explosion, such as Nuclear weapon. So they concluded that there is possibility that human came up from Mars to escape radiation and death. One interesting thing. Ancient people wrote that Giants came from Sky and they seeded life, and on Mars with less pressure/gravity people can growth higher.

  • If beings capable of building bombs had once lived on Mars we'd almost certainly have found evidence of their existence by now. If we're talking about Mars seeding life, it has been hypothesised that microbial life may have first arisen on Mars and later been transported to Earth by way of a chunk of rock. Look up exogenesis and panspermia, they are fascinating hypotheses 🙂

  • They call it rocket science because your firing a rocket from a moving, spinning, planet, to a place were in 8 months there is going to be a another moving, spinning, planet, although there isn't one there when it sets off, and your doing all of this in 3 dimensional space taking into effect the different gravitational forces of both planets……
    Simple huh 🙂

  • It's not hot at all. It's actually pretty cold on mars. The average temperature is -63 C. and it gets as cold as -123 C.

  • Guys I found this method and is very interesting, I'm not gettin rich but it is really giving me money, /watch?v=YaF1ZO4DjRs

  • Mars twin moons, what a spectacular view at night! Btw those moons aren't sphere shaped , they're deformed more like potato shaped. So crescent isn't what we're looking here.

  • they didn't mention the 14 minutes signal delay. Even if the vehicle and the satellites manage to dispatch the signal as planned, we still wouldn't know for 14 minutes or so until it gets here

  • Wow, i cant believe that i used to believe these assholes put men on the moon. Wow wasnt i a fucking brainwashed moron. I even used to believe in aliens. Hilarious. Now these assholes claim they found water on mars! Good shit. Wake up people

  • This is pure BS. That thing cannot possibly send a signal back to earth that will reach us.
    Do you know how much power it takes to send a radio signal just 60 miles?
    You think they can send a signal through the van allen belts? You know those belts block radiation dont you? Do you know how thick those belts are? And you think that nasa has anything that can punch through that? Kinda seems silly when you think about getting anything back from jupiter or saturn now doesnt it?
    If you have any doubt about what I'm saying, please see my youtube channel and checkout the short version of "why communication from mars is pure fantasy" . Bring your calculator and your white board.

  • I was wonder if nasa put satellites in between mars and earth could they get faster times on signals and communications

  • Dang crazy how I can hardly get service on my phone but these mf’s are sending signals from countless miles away? Also I’m curious when we sent these satellites that randomly popped up.

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