Questions about Rovers: Get Answers from NASA Scientists

[XMarzX]

Alright, so I'm a screenwriter and I've come across a problem; scientific accuracy. I'm not very smart in terms of science, so I need a little help.

The premise of the story goes like this; A group of NASA scientists send a rover up to Europa. It gives them video footage, and they can control its movements. They discover an intelligent Alien life form that has already made camp up there and is studying ocean lifeforms on the moon. They cannot communicate with it, but they can follow it around and see what its doing.

Here are my questions-

1. Is it actually possible to have a rover with video footage? What would have to have in order for this to be possible?
2. Eventually, the scientists would want to communicate with the alien. Is is possible to upgrade the rover from where they are, or would they have to send out another one that has such an upgrade?
3. I've been searching for ages to find stuff that can help me out with this concept, but can't find anything. Are they any good websites/books that cover rovers and other things like this?

Thanks so much for your guys' time and patience. Any advice is welcome.

 

[Rive]

Is it actually possible to have a rover with video footage?

The problem is not the capability of the rover, but the available data download speed which is not too much from that distance. Try to think about it as if you would only have an old-style 32k modem for Internet - as far as I know that's the maximal direct bandwidth of the Curiosity. Would you prefer low quality video, or high resolution still images?

Is is possible to upgrade the rover from where they are...

If the rover has a robotic arm of some kind then they might try to write on the surface/ice.

Ps.: you should also consider the delay: the value of a video feed is not really high if you can see it only a half hour later.

 

[.Scott]

So this rover will be about 400 million miles away and it will take signals more than half an hour to reach us.
We may want to include an orbiter with the rover - to serve as a communications link to Earth. And both the orbiter and the rover will be nuclear powered - just as the Martian Curiosity rover is. With enough power, a passable video signal is possible - although video is not the most efficient use of bandwidth for most scientific exploration objectives. Still, a video camera that could survive the Europa environment would not be expensive in terms of payload mass.

What is the medium of communication? Sounds waves propagated through the "air" is not a good answer. The Europa atmosphere is too tenuous for that to work. Perhaps sound propagated through the ground. Even if there was no microphone specifically designed to listen for "Europa-quakes", there could be an accelerator intended for navigation or trouble-shooting included on the rover that could, under software control, be co-opted for the task of listening for ground sound. Speaking might be possible by co-opting the drive wheel motors. Under software contol, it might be possible to adjust the speed of those motors to change at several hundred or even thousand Hertz - presumable sufficient for communications.

If communicatoin is by radio control, that would be more difficult. Most radio receivers and transmitters that would like be available to a rover would be a very specific and narrow range. But perhaps not. Let's say that you were using several small radar units for navigation - with one operating at say 80Ghz to 84GHz - that just happened to match one of the the aliens favorite communications frequency. Using SW, you could co-opt that device for communications. Such a radar device would have several programmable elements - including a signal processor and a MMIC (the actual RADAR chip). Spacecraft - rovers included - are often designed to allow remote reprogramming of their devices. So uploading new MMIC and processor software is very conceivable.

 

[.Scott]

Actually, that radar thing might work well into a story. As the rover moved inadvertently moved towards the alien camp, its 80GHz radar sensor starts showing phantom objects at a range of 250 to 350 meters. These same phantom objects are not seen from the cameras of the other radar units. After days of testing, it is determined that there is an external 83GHz source that is partially jamming the radar. The radar would then be reconfigured to capture that mysterious signal - and to home in on it. After the nature of the signal is determined to be a communications channel, the radar unit would be reconfigured again to allow two-way exchanges.

Using a radar unit in this way would have limitations. The signal it is transmitting can be modulated with digital information - but only very short "tweet"s at a time. Normally the MMIC simply sweeps their band linearly - in this case from 80 to 84GHz. But for communication, you would need to use another common feature of the MMIC that allows a pattern to be transmitted on the microwave signal. That pattern would be the message to be transmitted. Using the MMIC as a receiver would be similarly tricky. You would disconnect the transmit antennae and then "transmit" a signal at or near the carrier wave frequency (83GHz in our example). That would allow the mixers in your MMIC to demodulate (tune into) the signal. The demodulated signal is then digitized and sent to the RADAR signal processor where there will be ample data processing power to interpret and reformat almost any narrow bandwidth (Mbaud) communications signal. Given sufficient software and system development time (at least a couple of months of experimentation and repeated reprogramming), there could be little or no constraints on listening to the alien signal.

 

[member 656954]

A group of NASA scientists send a rover up to Europa. It gives them video footage, and they can control its movements.

As @Rive and @.Scott note, it is possible to send video, but remote control of any device so far away is not likely to work well. You don't "drive" it from that distance, it has to drive itself, so what's more practical is video or high-res imagery - and that should include other wavelengths than light - that is considered by Mission Control for options and actions, then a sequence of movement instructions sent back to the rover for it to execute. But an AI local controller makes more sense, and you could make it about as inquisitive / intelligent as a dog and possibly drive some of the plot that way?

But I'm wondering how far into our future your film happens? Europa’s ocean lies below a shell of ice we think is 10 to 15 miles thick, so drilling through to the suspected ocean underneath is a major engineering feat and we won't be sending "a rover" for that. It is also not a near-term activity, I'd not expect we've budget or materials science for another four or five decades at least.

So, is the intent that the rover is merely roaming the surface testing composition of the ice and looking for signs of life? That's likely a very different rover to any we've created to date, because it needs to traverse some very fractured icy landscapes in light gravity. Possibly a 'hopping' rover might work well in the 1.315m/s² gravity (that's about 13% of Earth) because tires and treads could be problematic.

Also, there needs to be a mechanism for the orbiter that lands the rover to reset the landing site from the planned landing site after noting the alien craft somehow. Otherwise, the odds of it landing anywhere near are pretty small. So, either Mission Control note it and redirect...or aliens find the rover, which simplifies your communications problem as the aliens would presumably be trying to communicate with us. Are they space faring aliens - I'm assuming so - which means they'll backtrack the signals from the rover to the orbiter to Earth pretty quickly. But you'll also need to consider why the Aliens haven't just come to Earth. It's way more obvious life is on Earth, so why visit Europa instead?

Now, if the alien craft has an orbiter (which seems probable), it's likely we'd have spotted it through telescopes before the rover launches, so we'd know something was going on. It seems contrived that the aliens would arrive after rover launch but before rover arrival. Also, unless the Aliens have faster than light craft (think wormholes or hyperdrive), we will notice them arriving in the Solar System - unless they've been here a while in which case, did they already visit Earth and move on? (Plus, various Jupiter missions would have seen their craft and equipment unless you give them really high-tech camouflage.) Their motivation can be opaque - consider Rendezvous with Rama - but that's not usually a satisfying story, so the 'why' of them ignoring Earth may need to be worked through because it will play into whether they interact with the rover or not.

Note that Europa Clipper and JUICE are both planned for launch in 2022 and the details of their missions might help with the orbital mechanics aspect - if you are taking that into account - and scanning equipment typical on a mission of this kind.

And JPL has two AR apps - "Spaceraft AR" and "Spacecraft 3D"- for smartphones that let you visually explore various Martian rovers. It provides a great feel for the size, mechanisms, and mechanics of these remote workhorses.

Finally, there is a great PC program called Stellarium that can help with distances between Earth and Europa at the point in time that your film is set.

 

[Bandersnatch]

Are they any good websites/books that cover rovers and other things like this?

There's a nice book describing in a digestible manner some aspects of engineering challenges for Mars rovers. It's called 'Roving Mars'.
If you google for <name of a mission> pdf, eg.: 'cassini pdf', you can find some documentation for various probes and their landers (where applicable). These might be a bit too technical for an average Joe, but some nuggets of valuable information may be found nonetheless.

 

[member 656954]

Incidentally @XMarzX, the Quirks and Quarks podcast had a panel discussion recently, Should we have humans in space?, that touches on rovers versus manned missions that might be useful background information. Astronaut Chris Hadfield is on the panel, and he provides good perspectives on both sides of the debate.

 

[russ_watters]

NASA used remotely controlled video cameras on the moon almost 50 years ago.

 

[hmmm27]

The paradigm for a video feed would be to buffer it all onboard, picking out an appropriate res/rate/compression for what's sent through the limited bandwidth depending on activity, anything the AI finds interesting, or human intervention, sending the rest during the boring periods. Same with the other sensors as well.

(Honestly surprised if they don't do that - or possibly something superior - now)

Looking forward to reading about the mini-robot that has its own compartment (r2d2 style), with dedicated arms/extensions for visegrips and wd-40, as well as bins labelled "duct tape" and "twine"

 

[FactChecker]

For science fiction, you can assume that the communication of the future is greatly improved and can send good video. There are physical limitations that you must not violate regarding the time a signal takes to get to and from Earth (35-51 minutes, depending on orbit positions). You could shorten that if you propose that humans are on nearer planets or spaceships. You can give the rover artificial intelligence to be less dependent on communications with humans.