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In my near future of manned Mars exploration, NASA/ESA/etc have a dozen or so rovers spread out around Mars. For scientific purposes, the rovers 'talk' to each other via low and high gain antennae bounced off of several orbiters. The rovers are similar to ours today and far enough away that they will never be near each other. NASA could look up these communications (likely in data form of course), but pretty much don't look into them: so largely autonomous.

Backdrop/storyline - one of our intrepid Astronauts uses this capability to spy on what another Astronaut is doing near a separate rover far away. In a light sense:

Mikey: "Curiosity, tell Spirit to take pictures of Mikey2."

What would be the most practical scientific purpose for having rovers communicate to each other without NASA's management? I'm looking for a scientific reason that they're programmed to routinely communicate just between each other.

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  • $\begingroup$ Just a OT question on your question. How much is "far away"? I think that a couple of km is manageable, but longer communication can be problematic because of the curvature without a high mountain or so. Maybe it's easier with a satellitar network? Something like 10-20 satellites orbiting the planet... $\endgroup$ – frarugi87 Mar 3 '17 at 8:17
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    $\begingroup$ @frarugi87 Note OP's mention of "bounced off of several orbiters", implying satellites in orbit. $\endgroup$ – a CVn Mar 3 '17 at 9:46
  • $\begingroup$ @MichaelKjörling oops... Totally missed that. Thank you $\endgroup$ – frarugi87 Mar 3 '17 at 15:53

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Geological Planetological research.

Electrical resistivity tomography is a short ranged (apparently couple hundred meters) imaging technique.

Seismology gathers and analyses data from seismic waves. It allows mapping of subsurface layers. Reflection seismology goes further, and instead of waiting for natural tremors to occur, it uses explosives to cause short ranged seismic waves when and how geologists want them.

Because of those reasons, you really want your rovers to be able to coordinate at up to ~2km ranges - for active research with explosives, and at global ranges for passive detection of natural seismic events. It's nearly certain that at some point, some areas would be deemed especially interesting and rovers would be deployed to map them for resources, interesting geological formations, water or any other reason. If you want single spot done by single machine, it would have to carry a lot of detachable detectors which could be laid down and later picked up, or it could be done by couple of rovers, including specialised carrier, deployer and perhaps recharger (and entire group designed to be mobile upwards to hundreds of kilometres). Whichever works for your story, but either way, you want your rovers to be able to warn others of incoming natural, global event, so they can lay down detectors and gather more data.

Better yet, for reflection seismology your rovers have a real need to carry explosives, if you ever want your story to have danger on top of those normally associated with space exploration.

EDIT: As for part about not looking into data. That one's easy in scenario outlined above. Data regarding rover coordination and warning isn't really important as long as system works. Scientists will want to look at data gathered AFTER, but communication leading to data gathering (one rover telling other that something global is on) will be analysed a first few times to test and benchmark the system and most likely ignored most of the time later on. Until someone decided to look into it to try to upgrade it, verify something or repurpose for another mission profile.

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  • $\begingroup$ You can do seismology without explosives : large shakers (search : Vibroseis ) work too. $\endgroup$ – Brian Drummond Mar 3 '17 at 13:05
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    $\begingroup$ But beware of the worms. $\endgroup$ – Brian Drummond Mar 3 '17 at 13:19
  • $\begingroup$ @BrianDrummond Thumper (trucks) exist specifically is to lure Shai-Hulud away. I think we should be safe. It is quite unfortunate that Ornithopters wouldn't work on that planet. $\endgroup$ – M i ech Mar 3 '17 at 13:32
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Redundancy.

Sending data from Mars is no picnic. Sometimes the data will not get through and at times it will take up to 24 minutes and getting a confirmation would take another 24 minutes. While you may say 48 minutes of data is not very valuable, but during these times, the Sun will be in between two planets which may cause communication problems. Thus, to make sure all data is secure, the best strategy is to duplicate it on multiple devices. While orbiters could be the best idea, they are even more fragile than the rovers on the ground. Thus all devices should be able to communicate and share information for backup. Spying could have done similar to how most systems are cracked on Earth, using a flaw in coding to inject arbitrary code for execution. This could allow Mikey to take control of all devices running the same bugged version of the software.

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They all use a common network, with circuit boards and software as used normally on Earth. Mars and the exploration consortium have their own isolated network, but things inside it behave just like normal IoT nodes. The rovers can talk to each other because the software stack and network fabric supports it; not from any deliberate need.

This could be extra sneaky if the person being monitored didn’t think that the rovers did talk to each other, while the spy realized they could.

In this case, if rover A were programmed (on the sly) to send a packet to rover B, it would just work, much like two computers in the same company but different subnets. It would send it to whichever orbiting platform was first available, which would see the address and send it back down when in range, and never bother the folks on Earth or inform anyone that this happened.

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  • $\begingroup$ Okay, I know that information can be sent between rovers and NASA, but I'm looking for a reason that they're routinely communicating just between each other. I'll try to amend my question to emphasize this. I like the idea in the second paragraph. $\endgroup$ – Mikey Mar 3 '17 at 2:37
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    $\begingroup$ @Mikey The rover revolution. They need to plan if they are going to take over Mars. Maybe it could be a redundant backup for signal loss between the rovers and the satellite. When the satellite goes down the rovers don't stop as they create a network between them selves and continue exploration until the satellite comes back up. $\endgroup$ – Snowlockk Mar 3 '17 at 9:39
  • $\begingroup$ @Snowlockk that’s only useful if the rovers in question are close together. If a “herd” of cooperating cheap units was deployed, this would be the norm. $\endgroup$ – JDługosz Mar 3 '17 at 20:45
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Some reasons off the top of my head:

  1. I encountered danger, here's what it looked like.
  2. I saw something worth exploring but it is too far away from my mission objective.
  3. My long range transmitter is broken or there's a mountain in the way of the transmission.
  4. I'll take this half of the crater, you take that half.
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  • $\begingroup$ I keep thinking of new reasons for them to communicate. Like many of my posts, this one started with "A couple of reasons...." $\endgroup$ – ShadoCat Mar 3 '17 at 0:07
  • $\begingroup$ This answer might benefit from being fleshed out a bit. $\endgroup$ – Burki Mar 3 '17 at 13:24
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To maintain research independence

Each of these rovers have a job to do, so if the same rovers in different locations are replicating work too much (and in effect wasting money), one of them should move onto another task. So, the rovers are aware of the main mission aims and redistribute tasks between them to get the most done in the shortest time.

Multi-band Communication

Sand storms on Mars could interfere with radio transmissions, resulting in lost or garbled messages. The rovers routinely re-broadcast mission directive instructions to each other (if you get the same message from two sources, it must be correct).

Plot

So, point one gives you the reason, point two allows you to "hack" the system in a plot-driven way (control two or three rovers and you gain control, lose a rover and you lose control).

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Martian Data-Subsystems Intranet

When NASA humans are actively driving the Rovers around, having them take specific pictures, and taking soil samples, etc. you can bet they want all the high-res images and everything bouncing off the nearest communications satellite and back to Earth as close to real time as they can. When the little guys are in autopilot or sleep-mode a lot of useful-but-boring information like current battery power, weather conditions, etc. are going to be a much lower priority for bandwidth. It would make a lot of sense for these sorts of mundane subsystems to communicate on a low-power local intranet.

Essentially, current Rovers (and likely future Rovers) have high-powered antennas for blasting information directly to Earth, but they also have (relative) low-powered antennas that can communicate with satellites that are in-Mars-orbit. In the future, with more Mars-orbit comms satellites in orbit, it makes more and more sense for rovers to save power by using the little antennas by default. Furthermore, if future Rovers are relatively close together (think walkie-talkie range) it might make sense to have direct rover-to-rover communications rather than beam every single datapoint out to Mars-satellites or Earth in real time.

Imagine all the Rovers have this local walkie-talkie short distance communication system. What would they want to talk about? The short answer is: nothing exciting. Data backup (for failure redundancy) is probably the main thing. If every rover backs up a copy of every other rover's data, then no data is irretrievably lost even if a meteor or harddrive failure takes out one of your fleet before it uploads its data to the next orbiting satellite. When everything is functioning properly (i.e. no failures), there's no reason* anyone at NASA is going to open the hood and look at how much bandwidth is being used bot-to-bot (* other than nerdy curiosity or someone doing an audit for routine systems maintenance).

Luckily for your snoopy Mikey1 character, sending backups of video data back and forth could be relatively high-bandwidth (depending on how much is being recorded at any given time) so his own data usage is likely a drop in the bucket. Furthermore, if the cameras of Rover2 are constantly recording Mikey2, then Mikey1 only has to issue a command of "Rover2 push real-time video data to Rover1 for backup." which is basically as innocuous as manually telling your computer to backup your photos now (to an external drive, or the cloud) instead of waiting for the scheduled backup time.

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Redundancy. Each rover echos it's findings -- images, raw instrument data, weather data, etc. -- to at least 2 other rovers, chosen randomly from the rovers that are online. Every time an instrument or camera is ready to send a load of data out, it sends it back to Earth and to another rover, so if a rover goes offline or if something prevents data transmission (weather, solar, mechanical failure), the data isn't lost and the mission can continue despite the failure.

Pings. Each rover pings the other rovers as a "heartbeat." If one of the rovers doesn't respond to the ping, then there's a problem, and the rovers report this back to NASA.

Duplication of effort. The rovers send each geolocation data. If two rovers happen to accidentally be on converging paths, they warn each other off and stop until NASA can assign new paths (or their internal AI can assign new paths).

Warnings. If rover 1 detects an oncoming dust storm, it sends out warning data to other rovers with wind speed and direction. Downwind rovers in the path of the storm can then plan accordingly to go into an automatic shutdown to save energy, prevent system damage, etc. during the storm. By having the warning, they can safely stop in-progress testing before the storm hits.

Distributed computing. If one rover is analyzing data and needs more processing power, it can offload some of the data to another rover that indicates it is (somewhat) idle. This effectively makes the rovers a "cloud computing" system, since some rovers might be at lower system utilization than others. Faster processing means faster delivery of results back to NASA.

Geolocation. By sending timing packets between rovers and between satellites, each rover can get a better fix on their current position and heading. This means fewer satellites are required to provide the Mars equivalent to GPS.

Local network. By having constant communications, there's the Mars equivalent to "wifi" for astronauts on the ground. This means the rovers can be the access points for smaller, lower-powered, robots or machines. This way, every machine on Mars doesn't have to pack the weight of a dish and battery capable of reaching satellites or Earth. They just have to be able to reach the nearest rover, which can then relay data to/from orbit or earth for that device. This allows more machines with smaller mass and lower power requirements.

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Say the capability is there for reasons of redundancy, as pointed out by ShadoCat. Any human on Mars can override orders from Earth or self-directed robot decisions.

This is a safety feature for the humans. If something goes wrong, some scenario nobody thought about, the humans can use any and all robots without waiting for permission from the back office. You need to get a rover stuck in a crater so it is in position to relay medical telemetry? Give the order, the rover obeys. You want to a rover to travel dozens of miles so you can scavenge the batteries for your habitat? Give the order, the rover obeys.

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They are autonomous, maybe they use some kind of self learning AI like neural networks to navigate and find interesting rocks to examine. To maximize learning capabilities they all exchange their inputs and decisions. But every rover still has its own AI because they have different instruments and research goals and to still be able to continue roving and doing science even if connection is somehow lost. Maybe by a defect in an orbiter or an dust storm which can last weeks on Mars.

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They are cataloguing the planet, trying to get new information. Their job will be more efficient if they can tell each other what they have already found, thereby avoiding repeating each others' work.

If they wish to explore the entire planet, they will need to share information on where they've already explored again to avoid overlap and waste resources. NASA can't plan their individual territories in advance, because they don't know in advance what they are going to find - one rover might end up spending the entire mission exploring one very interesting 1km^2 area while another may come across a huge featureless expanse and therefore cover a much larger area more quickly. Better to have an AI coordinate the exploration on the job.

Additionally, if a rover finds something that, for whatever reason, requires more than one rover to investigate, they'll need to be able to call others over.

Maybe one rover has many different types of cameras and its job is to take pictures and send them to another rover with high data processing power to analyse.

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In Preparation for War!

Right now, exploration of space is a fairly international venture with everyone cooperating for the betterment of all. Sometime in the future, that may change and in preparation for that day, the rovers have been designed to interact with each other without the need for fragile satellites and jammable interplanetary transmissions.

They have and use a planetary communication system for the same reason that they all have empty gun mounts on their retractable arms. So that if war ever reaches Mars, they will be ready to defend their owner's claim.

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The worst problem of the space probe control is that they can answer a command only hours later...

Thus, as it will happen, it will be around the same commands. I write it on human language:

  • "Here is your new firmware. Install it to yourself and reboot. If everything went well, then upload it also to your pal and say him to do the same."
  • "Upload half of the new photos from this interesting rock to your pal. Say him to start their sending to us. If he says everything is ok, delete them by you and make a lot of new photos in the free space."
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