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Note: Got the idea for this question by @uhoh's question: "Has anything close to video ("live" or otherwise) been shot in space from beyond the Moon ?

To have the "feeling" of a "live" connection with the Curiosity rover on Mars, why not send from there a real-time HD picture every 10 or 20 seconds for instance to be seen "directly" on NASA television ?

To give the inhabitants of the Earth the opportunity to experience what it's like to be on Mars.

Cornelis
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1 Answers1

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Why not? Because we can't.

  1. We don't have full-time communication with Curiosity: Curiosity sends data to the Mars Reconnaisance Orbiter and Mars Odyssey. These are overhead twice a day at 12-hour intervals. MRO and MO are in sun-synchronous orbits, so the planet rotates underneath the orbiter and they cover the entire planet in 1 day.

    Both are in orbits slightly under 2 hours long, so they're only above the horizon for a short time.

  2. During those communication passes, a limited amount of data can be uploaded. Curiosity was designed to upload 75 Mbit/day via Odyssey and 250 Mbit/day via MRO. The actual amount varies per day (depending on how high the orbiter is above the horizon), on some passes more data can be sent (up to 500 Mbit/day).

    1 image/10 seconds is 6 MB/minute is 360 MB/hour. So you'd saturate the uplink and there'd be no room for science data.

  3. Sending pictures every 10-20 seconds would interrupt driving (you don't want to take images while driving because they'd all be blurry) and hinder science operations. It would also eat into the rover's limited power budget.

  4. The rover drives for a maximum of 3 hours/day. The rest of the time it's stationary so you'd just be sending duplicate images (apart from the occasional mast movement).

The MSL image archive contains all images taken by the rover. Each camera takes images every day. The 2 navigation cameras take 4-150 images per day each, for example. For Sol 2250, about 280 images were taken by the 8 cameras.

Images are usually uploaded within a day, the image archive contains images taken yesterday. Sometimes images are stored on the rover because other data are given priority.

Data for most of this from Emily Lakdawalla's book 'The design and engineering of Curiosity'.

Hobbes
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  • Clear answer, so 1 image every 2 hours should be possible in practice ? – Cornelis Dec 08 '18 at 16:32
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    @Conelisinspace: Why should be 12 images a day been send if 9 or 10 would be duplicates? – Uwe Dec 08 '18 at 16:40
  • @Uwe That's the excitement of "live" pictures, you never know in advance. Also, images can be taken from different directions. – Cornelis Dec 08 '18 at 16:42
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    @Conelisinspace - they are nearly polar orbits. – amI Dec 08 '18 at 16:46
  • @amI Thanks to your comment i understand why orbits of 2 hours results in orbiters overhead only twice a day. – Cornelis Dec 08 '18 at 17:02
  • Very useful link to the MSL image archive ! (especially the Mastcam images) – Cornelis Dec 08 '18 at 18:12
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    It's not just what the rover can send, it's what Earth can receive. It takes rather more than your average radio antenna to pick up signals from space probes. NASA uses this: https://marsmobile.jpl.nasa.gov/msl/mission/communicationwithearth/ The DSN is not dedicated to one mission: it has to be timeshared between all of the probes out there. – jamesqf Dec 08 '18 at 18:28
  • well, yes. The data limits in my point 2 were arrived at by taking the limitations of the orbiters and the DSN into account. – Hobbes Dec 08 '18 at 18:33
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    Is Mb megabits? – Ruslan Dec 08 '18 at 20:06
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    Conventionally small-b means bits, and large-B means bytes, particularly when talking about telecommunications. – David Given Dec 08 '18 at 20:57
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    They'll never get pictures of the Martians if the image frequency is too low and predictable. – Barmar Dec 08 '18 at 21:09
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    "The rest of the time it's stationary so you'd just be sending duplicate images" Or... you could get images of Marvin walking around – WernerCD Dec 09 '18 at 01:46
  • Question how do the avoid obstacles and dangerous terrain, do they photograph surroundings and interpolate 3d surroundings and not have to do it again for long time? – marshal craft Dec 09 '18 at 05:19
  • @marshalcraft :go ahead and ask that as a new question. And there may have been a question about that already... – Hobbes Dec 09 '18 at 08:47
  • [citation needed] for the numbers you provide. According to https://mars.jpl.nasa.gov/msl/mission/communicationwithearth/data/, the real number is 100-250 Mb/day. – flaviut Dec 09 '18 at 21:29
  • it's megabits after all. – Hobbes Dec 10 '18 at 08:24