Help the author with her research: Infrared technology and other survey methods
March 16th, 2009 |A few months back a bunch of you all pitched in to help me figure out some FTL issues, and this time I’m asking for your scientific expertise on a subject a little closer to home. Er, sort of. I don’t think this is going to be too spoilerific, but if you’re concerned you can stop reading here!
In a nutshell, I’m trying to figure out exactly what the Galaxion can know about the planet below from up in orbit. From a plot point of view, there are things they can know and things they can’t. Or at least, temporarily can’t know. I’m not even thinking about fantastic new technologies here, I suspect even with our present level of tech they could learn quite a lot. Telescopic lenses are the most straightforward way of seeing what’s happening on the surface—that’s how Google Maps works, seeing stuff from satellites in orbit, and I believe the level of detail could be a lot higher. I can probably guess at the sort of limitations of a regular lens—the line of sight will be blocked by physical obstructions and will also be poor on a cloudy day.
Infrared sensors are another method of gathering surface data, but one I don’t grok quite as well. I understand with infrared imaging you can see stuff outside the range of human vision, such as the radiation from heat sources. I know astronomers use infrared telescopes to learn things about faraway stars, so using it to learn stuff about a planet you’re orbiting should be easy stuff. Movies and TV frequently show characters using some sort of thermal camera to clearly see people hidden in a building or behind a wall. How accurate is that? Can it be done from orbit, through the interference of the atmosphere? Could Fusella, on the Galaxion, be able to accurately track the positions of the Survey Contact Team? How about if they went inside a building? Or the Hiawatha? How much could clouds and other weather events mess up their ability to gather data? How about metal? Or rock?
I’m sure there are other methods of gathering data that haven’t even occurred to me. Some will likely not be important at all to the plot, but would be nice to at least think about. If you have any suggestions for me, I would be most grateful!
start here:
http://en.wikipedia.org/wiki/List_of_Earth_observation_satellites
then follow:
http://en.wikipedia.org/wiki/Landsat_7
And:
http://landsat.gsfc.nasa.gov/about/mss.html
I think this one holds great potential for storytelling
http://southport.jpl.nasa.gov/
to The Esteemed Author,
IANAP (I am not a physicist), but I do know many things which might help you with the plot, all using today’s technology. My experience is as an Amateur Radio Operator and former Machinist on a US Navy nuclear submarine (SSN-724).
Yes, you would be able to track surface teams fairly easily from orbit. I’ll assume that each team member has an emitting tracking device for this, and can relay location independently. If you have a cell-phone with mapping features, it uses GPS to find out where it is. Then it tells the server (elsewhere) its location and the server sends it maps so you can have a visual indication. Civilian cell-phone and GPS technology is deliberately crippled, cannot get information closer than a few meters, but as I recall the military hardware could track you to within a meter.
GPS is possible due to people like the forward-thinking Arthur C. Clarke, who in 1954 wrote a paper on Geostationary Telecommunications Satellites; look here for more information on that event. I suggest that tech during the time of Galaxion is accurate and inexpensive enough for the good ship to deploy several satellites slaved to her tracking and communications. These could be remotely controlled and/or collected when the survey is over. I think in terms of “Release the Probes” from older SciFi, but on a smaller scale, like as big as a breadbox.
But could the Galaxion track IR? I think so, although it’s more susceptible to heat interference from the surface than radio-frequencies. I think it more likely that a multi-spectrum radio frequency system will be in place on the Galaxion. If there’s interference (smoke, clouds, buildings) on one band, another could be used to receive information or track surface teams, as Hedy Lamarr, the really-great-actress, and composer George Antheil might have used from her patent in 1942. If I’m at a noisy party and cannot hear a piano playing a C note in one octave, maybe a lower-strength signal could be heard if all the C’s were played in succession, quickly. I would hear regular intervals of similar sounds and be better able to tell what’s going on.
As far as tracking is concerned, visible light, IR, radio, anything we can currently detect now at long ranges is fair game. We can even track magnetic signatures below the sea. NASA will give up directing the Voyager 1 space probe in a few years, but it can still be tracked by amateurs. It has a very low power output, and at that distance it’s like looking at a candle burning on the surface of the moon.
All said, I think it would take an act of physically interrupting the transmission or reception of a signal before someone got lost between orbit and surface. Here’s a snapshot of what’s available: . Nuclear radiation (particles and gamma radiation) we can detect as well, but those emissions would be dangerous to people nearby. The safest are low-power radio, visible light and infrared. All EM signals can bounce or reflect from objects, which is why some cell-phones work in elevators. Shorter wavelengths can pass more easily through some objects, longer ones are easily blocked. Tracking IR through walls works better if you’re up close to the wall; like scanners at airports that “see-through” clothing, it is limited in range.
But by the Galaxion’s time this might not be a problem.
Thanks for writing a fabulous strip!
Regards,
Mike Rice
KB0NND
Ack! I should not have used the wrong quotes around my websites references! Here they are:
http://en.wikipedia.org/wiki/Arthur_C_Clarke#Concept_of_the_geostationary_communications_satellite
http://en.wikipedia.org/wiki/Spread_spectrum#Frequency_Hopping
http://en.wikipedia.org/wiki/Electromagnetic_spectrum
Can you tell I like Wikipedia? Correctly maligned, but still reasonable for some references!
This is an interesting subject and, darn it, I’m not even remotely qualified to talk about it. But that won’t stop me. Re infrared, one thing I do know is, the further away you are, the bigger a heat signature would need to be to be seen. You can feel the heat of the sun, but alpha centauri is just too far away for its infrared to register on our organic detectors. I don’t know if current tech is sensitive enough to detect a human from orbit, or even the heat produced by, say, an internal combustion engine. I doubt it. I expect UV is a better bet. Ultraviolet is what causes sunburn, even on a cloudy day when you feel cool, so at least in some respects the rays penetrate better than IR. There is also the night vision aspect – I understand UV goggles give a good clear picture, vs the heat blur one sees with IR goggles. One advantage of IR over UV is that heat DOES penetrate walls (the reason for the housing insulation industry). A body also gives off its own heat, so no external heat source is needed to see it with an IR detector.
The main question is knowing where to look! A survey team will have transponders, certainly (my dad wears one on his ankle to help S&R find him if he wanders off [he has alzheimers]), so the main ship will always have a good fix on their location unless they get far enough underground that the signal is blocked. Any team that might expect to do so might bring repeaters which could help maintain signal in uncertain areas, though that might depend on regulations regarding leaving tech lying around on unknown planets. Depending on circumstances, the main ship might also orbit a satellite or two to help triangulate transponder signals.
For general survey, start with emission detection. Any radio waves or strong IR hotspots? Good way to find radio stations and volcanoes, or towns & cities if they have foundries. Certainly a few orbits are necessary to be sure the entire surface is seen by day & night (night-time sources of light are also a good way to find volcanoes and towns). Finally, visual work from orbit with computer assistance is key. The computer picks out anomalies (glints of light, strong reflections, etc), which are referred to crew for closer examination.
I put a disclaimer at the top, and here is another one: this is just my limited understanding of these matters. I may be mistaken in some or all particulars, though I don’t think so…
Infrared imaging covers a variety of wavelengths, from near-infrared (NIR; just outside human vision, acts almost identical to visible light), through short-wave (SWIR; main region for telecom, usable for sensing, but still requires illumination) to medium-wave and long-wave (MWIR and LWIR, containing thermal emissions from objects’ heat).
NIR is what’s used in conventional night-vision gear. No objects at reasonable temperatures glow in this region, so illumination of some sort is necessary — from orbit, this means you need one of: the sun shining, illumination by someone on-ground with an IR spotlight, or a deliberately emitting target. Like visible light, even light tree cover will reduce visibility dramatically, and almost any roof will block it completely. In daylight, since it offers no seeing advantage over visible light, there’s no point. Using it to monitor a team on-ground using night-vision and NIR illuminators is certainly possible, as is tracking any NIR beacons. Both of these make sense principally if there’s a reason for stealth; otherwise the spotlights or beacons might as well be visible.
SWIR has a number of strong water absorption bands, wavelengths where water (liquid or vapor) is opaque. Since the atmosphere of an Earth-like planet has water vapor in it, you have to use the wavelengths between these. Otherwise, it’s fairly like NIR in overall characteristics, but will penetrate a few optically opaque materials, and will be blocked by a few optically transparent materials (notably ordinary glass, for some wavelengths). Again, it requires illumination, whether sunlight or artificial.
MWIR allows thermal imaging, but objects of body temperature or so don’t show up real well. Hot objects show up great though; this is good for picking up hot metal and gasses from engines. It also is the best range for seeing through cloud cover. It works at night or in daylight, and can (given some knowledge of what you’re looking at, or at least good guesswork) make temperature measurements. (So you could determine that a tent is warm, but you still can’t actually see the person inside whose body heat is responsible.)
LWIR sees through smoke and dust even better than MWIR, but does not see through clouds well – in fact, weather satellites use LWIR to measure temperature of the tops of clouds. This sees low-temperature objects better, including body heat. Again, no illumination needed, and you can measure temperatures. And you still can’t image people through walls.
Now, the downside of the longer wavelengths is simple: the longer the wavelength, the larger your camera/antenna has to be to match resolution. Since light is around 500nm, and LWIR is around 10um, the LWIR will have 1/20 the resolution for the same aperture. If you had 6″ resolution optically, that would be 10 feet in LWIR, and maybe 5 feet in MWIR. You’d probably use larger lenses, but I’d guess you still won’t get the same resolution as your optic system. The M/LWIR also wind up being expensive and complicated, needing cryogenic refrigeration to prevent the heat from the camera itself swamping the image, but I’m sure that’s all standard in a ship like the Galaxion.
Here’s a little something that might help. http://en.wikipedia.org/wiki/Radio_window
Remember, though, that since clouds are made of water, which absorbs infrared wavelengths particularly well, even thin clouds can obstruct visibility. There might be future technologies to counteract that, but it’s possible that a thick cloud absorbs all incoming infrared, at which point no tricks will help you to see through it.
I’m no signals engineer either, but all that sounds sensible to me. Here’s some more random layperson-level suggestions:
* Don’t forget radar. After passive optical and radio-frequency imaging, it seems like a ship should be able to do active radar scans (as we did with Magellen on Venus – http://en.wikipedia.org/wiki/Magellan_probe – ) to peek terrain through clouds
* There would probably be massive amounts of imaging data – terabytes or more – potentially generated and limited time to get it all, so I would expect the search protocol to involve doing very rough estimates of wide areas of interest, then narrowing down. Even if you could get perfect visibility, the closer a search could be narrowed, the more information you’d get.
* I dunno if the world of Galaxion includes robot probes, but I think if I were an away team I’d want some kind of automated flier to flit around and get up-close footage and build up 3D models. It doesn’t have to be an either/or thing between ‘watch from orbit’ and ‘go there on foot’.
* If you land with a shuttle, I’d use the shuttle as a base station for signal repeating, and maybe a microsatellite and/or high-altitude balloon. If you’re going to bring down that much gear you might as well make sure you don’t lose your communications link. Auroras and electrical storms could block radio signals, but if you’ve got warp drive and artificial gravity you’ve probably got some form of gravity-based communication too,
Infra-red monitors can do a lot of ecological scanning because plants, ocean currents, and weather patterns all have distinct heat signatures.
Optical surveying is the easiest method and done from above is generally referred to as ‘Aerial Surveying’… However more advanced types of surveying are common to, such as: RADAR imaging surveys, atmospheric composition testing, geological surveying, exotic penetrating surface tests (T rays, side band resonance, magnetic imaging, etc), when it’s felt needed.Once your on the ground you can also do soil sampling, subsurface SONAR imaging, and surface level environmental tests.
The gist of all this testing though is that we not only can see what the surface looks like, but we usually can tell what it’s made of and get an idea of how deep the surface material is. Using the ship as an example, it probably showed up as a big metallic object so they would zip a camera over for some detailed images from above. From there some RADAR imaging should give a good 3D map of it even when combined with the optical imaging and some other orbital surveying should be able to even give an idea if it had been caught in an explosion or combat of some sort (by comparing it to what it should be made up of on the outside and what it seems to be made up of now, so their would be things like carbon scoring if either had happened).
Something like that was done to find out the details of the ‘face’ on mars to determine it was really just a Martian dune that was giving off an interesting shadow effect when the picture was taken.
And that is the limit of what I remember on the subject off the top of my head…
Oooh! Remote sensing goodness!
There is a lot that we can learn just from orbital sensing. Radar, visual, and IR have all been mentioned and I’d imagine by the time Galaxion is set in (200 years hence? 300?) resolution of cameras will have improved immensely. Today we can place stuff on Earth-orbiting satellites that can resolve down to 1 pixel = 1 metre, and possibly better. Space probes going to the outer solar system are under power, bandwidth, and mass restrictions, so less sophisticated cameras usually get put on those. We are even reaching the point where we will be able to tell a significant amount of information about extrasolar planets simply from spectral analysis (the Kepler orbital telescope that went into orbit recently should not only be able to detect planets, but – due to the method used (transit of planet in front of its sun) – will be able to either detect the atmosphere composition or even the pigment that local plants might be using).
The big problem I can see is coverage, and that will depend in part on how well equipped the Galaxion was when it left port (they didn’t have a full SCT available – what else are they missing?) and in part on the orbit the Galaxion is in. AlpineBob mentions this detail, but let’s expand on it.
Galaxion can easily cover a full third of “para-Earth” simply by remaining in what we would call Clarke orbit. The big problems I can see with such an orbit would be (1) we don’t know where the Hiawatha crashed (it could be in higher latitudes, giving the Galaxion’s sensors and cameras several hundred kilometers of atmosphere to punch through), (2) distance for landers to travel: assuming para-Earth is equal in mass and radius to our Earth, Clarke orbit translates to approx 36,000 kilometers from planet surface – that’s a long way for a ship to travel, especially if you need to land / take off in a hurry, and (3) lack of coverage of 2/3rds of para-Earth’s surface.
Lower orbits allow for less travel time from orbit to surface and allow the Galaxion to cover large parts of the planet’s surface in scanning, but you will lose direct contact ability with the SCT and the Hiawatha crash site. Also, it was mentioned by someone else that – given the post-apocalyptic state of para-Earth – there could be a lot of debris in low orbit.
Both scenarios are helped out significantly by satellites, though I’d venture that for best coverage, and best tracking capacity, a GPS / Galileo-like satellite network would be required. That”s 24 satellites all placed in specific orbits. Again, with 200 years of advancement, these satellites might be less massive than present-day GPS satellites, as well as loaded with all sorts of remote-sensing goodies. Galaxion might even have some nanotech-based manufacturing capacity aboard, allowing them to manufacture quick-and-dirty satellite replacements if necessary (though that is rank speculation on my part).
One thing I would stay away from would be neutrino scanning. While neutrinos are cool, they are also very difficult to detect – we can only do so today using several tonnes of water and networks of photomultiplier tubes buried deep underground; I’d venture that this is one detection method that would be difficult if not impossible to miniaturize.
And don’t forget the mark 1 eyeball. Existing cities can be seen on the night side.
I agree with Nate. Galaxion should carry orbital, sub-orbital and recon drones.
As an arm-chair starfleet captain it drove me nuts that they never secured orbit or did recon on the landing site before beaming down senior staff.
Just this week the crew of the ISS had a debris scare. This is what I found fascinating:
{ The US Strategic Command notified NASA of the debris field late Wednesday, but NASA said it was too late for flight controllers to coordinate a “debris avoidance” maneuver.
“Every once in a while, the crew has to do orbital debris avoidance maneuvers but this time they didn’t do that because we have an upcoming launch possibly on Sunday and they need to stay at the same altitude,” Rochon said.
The US Joint Space Operations Center tracks about 18,000 objects in orbit, so many that it has to decide which to follow most closely, like those that might fly by the International Space Station or manned space flights. } Source: http://news.yahoo.com/s/afp/20090312/ts_alt_afp/usspaceissemergency
Okay US JSOC tracks 18,000 objects in orbit, right? Now here’s the kicker from NPR:
{ The piece of junk being tracked is about 4 inches and comes from a Russian satellite that broke up in 1981. }
We’re able to track an object the size of a softball in orbit “Traveling at speeds of up to thousands of miles an hour”? Sweet barking cheese!
How much info can they obtain? Galaxion should be able to read a menu from orbit.
IR is just light emitted in a wavelenght below red. It’s just that, light. It turns out that this light is emitted by warm objects, just light visible light is emitted by very hot objects such as a red-hot piece of metal.
As far as infrared goes, with today’s technology, we can detect very minute temperature differences. Think tenth of a degree. This lets us identify warm objects such as machinery.
IR allows a satellite to accurately identify a crop or a vegetation type, by comparing the visible and IR signature of a vegetation patch to a databank of known plant signatures. On another planet, we’d not be so lucky, since the plants would be unknown, but we’d still be able to differentiate bare terrain from, say, a wooded area.
As far as tracking a team on the surgace from orbit, you’d have to imagine that your IR sensor has an excelent definition, say, 20 cm (8 in.). Today’s commercial imagery has a resolution of about 50 cm, so doubling that isn’t very far fetched. So yes, you could do it, especially at night. During the day, the team could carry a strobe, which is an IR source (e.g., a sed of IR LEDs just like in a TV remote) that pulsates. This is a very unnatural phenomenon that is unlikely to be duplicated by anything living on the planet, hence allowing an IR sensor to differenciate the surface team from anything else, including other humans that lack the strobe. Identification strobes are already used by the military to mark friendlies from hostiles in a close-combat situation.
The problem with IR is that it’s absorbed by water vapor. Clouds, or even high humidity (fog) ,hamper IR remote sensing. And of course, once you are underground (or in a building), IR remote sensing is useless.
As for radar, even a small, low power radar can penetrate several meters underground and reveal burried buildings, ruin foundations, and even filled up ditches. More powerful versions can detect underground water tables and steams. Radar cannot penetrate Anything conductive (such as water and metal), which is why you cannot use radar to see submarines under water.
Humans are not especially good radar targets, but a good radar includes a Doppler stage, which detects motion by Doppler effect. As of now, it’s very hard to detect human-sized targets from orbit by Doppler, but with a couple of centuries of tech improvements, why not? And if, on top of that, your team is kind enough to carry a radar transponder (which sends a special beep when painted by a radar pulse), then a small radar would be able to localize the team members from orbit, and even identify them from their transponder codes. Today, this would require a radar drone overhead, but in 20 years, this should be achievable from orbit.
Finally, for backup, don’t forget that your ship is in orbit and is therefore on the top of a gravity well. If the crew members have a modicum of clue and equipment, they can fit a retrorocket on a solid piece of metal and deorbit it, making it fall wherever they want, with an impact that has the same energy as several tons of TNT. This system is known as “smart pebble”.
One more thing: tracking people underground or in a building would not be possible by IR (in spite of what movies show). With the help of radar, you could possibly track a team underground, through a few meters of rock, but not underwater or in a building (or ship).
There is also a technology that hasn’t been mentioned. Neutrino and neutron detection. See, they are particles that only weakly interact with matter and are given off by fusion and fission reactions. Currently our detectors are huge devices, like vast indoor swimming pools lined with ultra sensitive light detectors that look for the tell-tale flash of Chekhov radiation when a neutrino passes though the fluid.
However, smaller solid-sate detectors have been proposed, and it’s not unreasonable to imagine that 200 years from now they’d have something that could be ship mounted and capable of a fair degree of resolution.
Thing is…with a neutrino detector it would like the entire planet was made of glass and back-lit by the sun…not to mention the neutrons given off natural fission decay within rocks. With enough resolution, [say down to 10cm] you could scan the insides of buildings and crashed spacecraft with not too much difficulty. Of course, resolving low mass objects, such as organics would be difficult. basically it would be an x-ray really.
However, if you wanted to track a team on the surface, you could issue them with a glow-light that uses a mildly radioactive luminescent substance, such as tritium/barium sulphate, that glows in the dark..that would emit a small number of neutrons and could be tracked. [although, if they lost it, that would be a problem.]
Probably ground-based repeaters would be needed to cover any kind of tracking in deep caves, buildings, or ruins. Granted, that means more stuff the SCT has to carry with them, but again, I’d envision such repeaters would be pretty lightweight. Repeaters would also help the SCT in the event that they lose (or have only partial) communications access with the Galaxion, the satellite network, and the lander and they need to be able to find their way around.
Redundancy works!
A question for Tara: while the SCT is human-centered, I’m wondering if robots are employed to any extent in survey operations? I’m thinking machines like the Mars rovers, rather than full-fledged bots like TNG’s Lt. Cmdr. Data (especially since the rovers would be cheap, expendable, lightweight, and almost endlessly adaptable).
Something mechanical you may want to consider: Interferometry. There’s a limit on the resolution you can obtain for a given aperture size, and interferometry is one way to get around that limit (essentially by combining the signals from multiple smaller sensors; the final resolution is the same as a device as large as the smaller detectors are from each other).
An interferometric IR sensor would not be too far out there for Galaxion to have, and would easily enable them to see crew members on the surface (the mathematics on the array diameter you’d need is pretty straightforward). The Galaxion could deploy sensors (little more than a telescope, CCD and a timing device, plus associated connective/data cabling) to create a wider aperture – you could probably hand-wave some station-keeping thrusters, etc. to keep them properly aligned (this could actually be done at visual wavelengths as well, but the allowable errors are much, much smaller). As an added plus, they could be deployed in such a way to make the Galaxion resemble a nautilus that much more =O).
BTW, long-time lurker here, great comic!
When I first saw Tara’s question last night, I backed off. My initial reaction was, “Ugh! Too much information. I need to think about this.” The fact is that even limited to currently available scanning technology, on a platform as large and powerful as the Galaxion, they will know, in painfully redundant detail, what’s down there. Their first problem will be sifting out the mission-critical data. Context, they will have to acquire with boots on the ground.
BTW, the above posts are all dead on the money, but they only begin to suggest the power of presently available scanning and image processing technology. A little research would shock your socks off, and that’s only the information that’s available to the public.
Current pattern analysis software should be able to classify types of terrain, terrain features, manmade structures, and disturbances. They should be able to do all of this with just the visible spectrum, though providing access to all spectrums would help.
Since the planet is very similar to Earth, this will simplify the scanning by several orders of magnitude over other planets. They can tune their sensors for Earth atmosphere and may even have databases of Earth data for comparison.
Several questions come up that, although moot now with Page 2, is relevant to the conversation: even though this is a similar Earth, that does not rule out the fact that the atmosphere might NOT be breathable. The survey team needs to come to grips with this before considering landing on the surface.
Two reasons come to mind:
(1) the chemical composition in the atmosphere might afford life for floral and certain fauna, but humans require a specific mix of oxygen, nitrogen, and tolerable minute traces of other gases in order to breathe. For example, most people are used to the concentration of oxygen at sea level, but the concentration decreases rapidly for every thousand feet of elevation above sea level and makes breathing harder. I’m assuming spectral analysis of the atmosphere is possible.
(2) if the chemical composition of the atmosphere is conducive to human habitation, then the question of airborne biological variables is the second. There may be some remote sensing for certain items like pollen or spore clouds, but germs that are resilient to the elements of the weather will be a major threat. We, as humans, have lived on this Earth in co-habitation. By the very fact that we have survived all the germs and viruses and other diseases that the planet has created gives us the ability to survive it. The same cannot be said when we go to other planets with advanced life as this Alternative Earth. (War of the Worlds is one example that springs to mind.)
This may have gotten off topic, but it is something to consider when using remote sensing to make a First Contact Engagement Matrix. (I just threw that in for effect. I kinda like it.)
–HardWearJunkie
Wow– you guys are all amazing!
Sorry for the long delay in responding to this topic– this is March Break for us, the kids are home from school and we’ve been pretty busy. I just haven’t had, up til now, enough time and brain power to sit down and absorb all this great information! Thank you!! You’ve all given me a lot to think about. I know I can’t use it all directly– if I went into too much detail about how the ship and team are analyzing the planet the story would creak to a halt and the readers– even you keeners! — would fall asleep. But all this is great for background info. Even if I end up having to hand-wave and technobabble some of it away!
It seems like a better question would have been, “What can’t they know?” Haha. From all of your comments, and from what I’ve already read, I’m thinking that a lot of data will be gathered but the real work will be in the months ahead when they sit down and study what they’ve found and what it means. Even in the future, I’m sure it’s safe to assume the computers will only do so much for you. In a more usual survey, the team may return several times to hit all the areas of interest.
It amuses me to imagine the analysis team on the ship being frustrated by having an Earth-like planet to study. They’re used to planets and planetoids with little-to-no atmosphere, where they’ll have the full electromagnetic spectrum to command, when scanning the planet. On this unexpected mission, much of their usual bag of tricks will be blocked or hampered by the atmosphere… I can picture the scene with Mal and his buddies banging their heads against the wall already! They’ll have to get creative. (Although it’s a bit like reinventing the wheel, isn’t it?)
Would you think it reasonable, then, that the Galaxion would not be able to detect other humans from orbit? At least, not easily? And if they did know other humans were present, tracking them from orbit would be difficult?
Also, about the debris in orbit around the planet… I admit, I haven’t thought about that before. But I know satellites in low orbit eventually degrade and get pulled back down to Earth. Part of the job of the shuttle, as I understand it, is to give the ISS a periodic boost to keep it up there. Wouldn’t most of the stuff people on this alternate Earth put into orbit have fallen back into the atmosphere by now? Or does the really little stuff (like that 4-inch projectile Baxter mentioned–yikes!) stay up there indefinitely?
Since radio waves pass entirely unaffected through a planet’s atmosphere (specifically Earth’s, but it would hold true for any terracompatible world), RADAR’s a damned good way to find out physical aspects of the planet’s surface. Trouble is that it wouldn’t build up a particularly detailed picture. After all, all a RADAR station does is tell you there’s a plane out there, not show you exactly what it looks like. That’s what microwave RADAR’s for. Radio stretches from tens of kilometres in wavelength down to tens of millimetres. That encompasses microwaves, which are technically a kind of radio wave. The wavelength specifies the eventual resolution of the image that can be built up. The smaller the wavelength, the higher the resolution – meaning better detail.
Only thing is that microwaves are around 50% blocked by the atmosphere, so power requirements would be higher. I’d tend to assume that a basic picture could be built up with RADAR in the 10cm to 1m wavelength range, and a second pass with the microwave RADAR would gather more detail in the interesting areas. Microwave RADAR, for example, could easily map someone’s face from orbit, assuming the power was available.
Regarding orbit – LEO (Low Earth Orbit) objects have their orbits decayed by the upper fringes of the atmosphere. The larger the item, the larger the drag (higher likelyhood of collisions with the sparse particles), but the more massive the item, the less it would be affected. Anything out in a higher orbit would remain indefinitely. Something very small (such as the 4-inch projectile) would, in effect, stay there forever, even in LEO. It would EVENTUALLY find its way down into the atmosphere, but it would take so long as to be eternal to several generations, at least. I’d just like to point out, though, that the reason we can track it is because we knew where it was at one point (not too difficult with RADAR) and its velocity at that point. Thus, we feed that into orbital mechanics, and we can predict its path for decades to come. We don’t need to pay attention to where everything is at all times, because we can just work out where it is and point the telescopes at it.
Debris isn’t a problem if there’s a significant amount of time involved (on the order of hundreds-thousands of years). I also imagine that if the Galaxion can travel at superluminal speeds, then it must have a reinforced hull anyways, so only the large debris is of major concern (assuming there are crews that do daily(?) hull checks/patch jobs).
It’s reasonable that the Galaxion wouldn’t be able to see some civilizations: underground/water ones, as noted above, and something in heavily forested areas (depending on how advanced the civilization is, it may show up thermally, but wouldn’t be distinguishable from whatever other life forms are floating around). Also, depending on how advanced the computers are, it’s entirely possible that it would take a really long time to do a comprehensive analysis that could pull out signs of civilization (though having found the Hiawatha, I imagine they’re pretty durn powerful).
HardWearJunkie: Determining content of the atmosphere is easy – spectral analysis is well-known and commonplace in modern space exploration. The point about biological threats is an excellent one, so the team would likely need to have some form of environmental protection from aerosol threats (implanted filters in the lungs? =O) ).
Finding unknown, lowish tech, individual humans would be very much a needle in a haystack endeavor. I’m thinking primarily due to the sheer scale of a planet. You could do a quickie scan, well, quickly, but it wouldn’t tell you much about small things. Taking a higher resolution scan would be doable, but quite time consuming. So you’d either be doing areas at random or already have an area picked out beforehand. Then you still have to evaluate your massive pile of data (and I do mean MASSIVE). I’m guessing this would be the biggest bottleneck (the detailed scan just being time consuming), computer and human ability to process and filter this sort of information still seems to be some flavor of ‘slow’ in the Galaxion universe. This alone should give you the initial time and ignorance window you need for your story.
So finding someone at random would take forever and use up lots and lots of computer and human time. However, once you have found someone I can see it being relatively simple to KEEP knowing about them. Even if your orbit takes you out of LOS and you did not seed a few satellites (unlikely for a survey ship, but it is undermanned), you still know where they were, and unless they can hide or cover massive amounts of distance, you could reacquire them after a short search since you could really focus on a really small area.
Orbital debris could be a significant worry. Stuff tends to stay up there unless something else acts on it (at least for human definitions of time), and collisions tend to make things exponentially worse. So it really depends on the space presence of Earth 2 humanity before their fall, if the warfare actually spilled into orbit, and how long ago this was. If they had moved into orbit, and even one orbital facility was attacked/destroyed, it could get really nasty up there for at least hundreds of years.
Part of our problem in real life is we have been rather sloppy and irresponsible with rocket and satellite leftovers IMHO, and even that is enough to be a pain. Hell I remember seeing a picture of the damage a fleck of paint did to a window at orbital speeds!
All this reminds me of a hard scifi manga called Planetes. The first half was all about the crew of an orbital garbage cleanup ship. How the junk was dangerous yet more kept being made/released even though the dangers were well known.
Sorry, a little bubble bursting, then some options.
GPS would not exist on this planet, it is based on geosynchronous orbits at established heights that can reliably collect data from radio transmissions, correct for interference/error, and calculate position with the aid of known ground points. so long and short is no GPS will not work without a lot of prep time being put in.
New bubble: unmanned aerial drones can fly for hours now on existing solar power technology and the tech surely would have improved by this time(or i voted for completely the wrong guys). So using a small fleet of unmanned drones flying in a controlled and perdictable pattern formation they could keep relative close tabs on the ground crew and the immediate surroundings and relay comms back up to the ship with out interference and on a heavily coded military band. lowering their altitude could allow them to keep contact if the crew were to enter the Hiawatha, and possibly the could land and divert all power to their radio units to boost signal to max range, but they would lose tracking abilities if they lost line of sight/landed in the brush you’ve already depicted (excellently) so you could offer that as well.
As for whole planet scanning, Thermal imaging on the night side is the best way unless many smaller craft are available for a gridded picture taking mission. Digital pictures that could then be fed through software that recognizes and pin points visual anomalies. I suppose rough time lapse scans of the surface by sensors on the main ship could approximate thermal, chemical/spectral, radioactive, or radar-based readings to basic area quadrants. Probably about a GPS 100 square minutes (ten by ten) is reasonable for a recognizable area from orbit by rough detection
I must annotate! In the above i completely discounted dirigibles for the unmanned vehicles. they could be manned or not, and have a huge area so could stay aloft while diverting practically all power to communications equipment and radar systems. plus, they store quite nicely, and would not take much room or time to set up.
I loved Planetes! I wish there was more of it. But I agree that the type of debris field they’re likely to encounter in orbit there won’t be much of a worry to the Galaxion. If they can’t handle that kind of stuff they don’t belong in space!
I’m… not sure how they deal with general airborne threats. Implanted lung filters sounds a bit icky to me! On the other hand, I’m sure they wear space suits on the usual survey mission, so filters are part of the package. To some extent, a member of the SCT knows the job comes with these kind of risks. There was probably a great deal of debate over whether they should wear full suits on this trip, but through the magic of comic closure that’s all left to the imagination…
Oh, and incidentally, the Hiawatha is still emitting some sort of weak mayday beacon, which is how the Galaxion found her so quickly. This gets mentioned later in the chapter.
The best way to detect low-tech human activity might be fire… not that common in nature.
Oi! Go offline for 24 hours and the comments explode!
Concerning airborne stuff: I may be way off base here, but given what I’ve seen so far, my guess is that the “split” point between real Earth and para-Earth is somewhere in the last 50-100 years (but then there are those troubling anomalies with placement of stars and the shape of nebulae…), so we can expect that biological evolution hasn’t done too much in the way of allergens. Pollen on para-Earth would be the same as pollen on real Earth (although colonists like Ari might find themselves needing antihistamines very quickly).
Bacteria and viruses may or may not be a threat – after all, on para-Earth it appears that humans were present and hence provided a suitable host for some diseases to thrive, but they are also recent departures (extinct for 50 years, or as good as extinct), so many diseases may have either found new hosts or vanished. Keep in mind that 50 years is a long time to bacteria – hundreds of generations – and evolution proceeds at a breakneck speed for them. Still, there may still be the occasional bug that might make the jump back to humans in an instant, so my recommendation to dealing with that would be the same thing they did with the Apollo astronauts – a week-long quartantine once they get back to the ship (though not with the gels and paste they had in Enterprise – I always found those scenes to be far too fanservice-y for my taste…)
As for GPS or lack thereof: Given that we’ve seen the Galaxion perform some… rigourous surface scans, I’d gather that position data for a GPS system could be computed with relative ease. Also remember we are looking at 200+ years advancement from our current state. I doubt Moore’s Law will hold for the entire period, but it’s a safe bet that the computers aboard the Galaxion have a lot more processing power than even our most advanced supercomputers today (heck, I’d expect that their handheld computers would have more processing power than our supercomputers). Setting up a future GPS system over an unknown planet will therefore not be an insurmoutable obstacle (though I concede it would not be Step 1 of Survey Operations – perhaps GPS setup would occur between Orbital Survey and Surface Operations). Of course, it also depends on if TerSA and IP decided they would need a programmable GPS network for this mission (I’m remembering that scene from Star Trek: Generations: “You left Spacedock without a tractor beam?!” “It won’t be installed until Tuesday.”)
As for Mal and company banging their heads… maybe, but I can also see them loving every minute of it. After all, science is the ultimate demonstration of “getting there is half the fun” ^_^
Yes, that is true– Mal and crew would have a great time puzzling it out. The weirder the better.
I haven’t yet gone into great detail about the “rules” of first contact, but one thing to know is the Survey Contact Team is only the first team on the surface. They are trained to make first contact, and determine that the area is safe for a larger and better equipped team. There are also limits on how much tech they can have– they have to be careful about leaving stuff around– so the idea of sticking repeaters across the landscape and that sort of thing wouldn’t work. Although putting temporary satellites in orbit for triangulation and such might be acceptable.
Joe Craft’s idea about using unmanned drones or dirigibles as repeaters and for low-level scans is interesting. Probably not necessary with a Galaxion level tech. Though given that Fusella’s transmission is breaking up on the current page, perhaps they would be more useful than I, or they, thought.
Come to think of it, they have artifical gravity, so it seems like they could have gravity-floating drones. If I was first contact that’s what I would want – send one ahead of the personnel for a threat scan – drones are cheaper than people (especially if I’m one of the people). I guess they don’t have that tech, though, or we’d have seen worker drones floating through the Galaxion. I’m sure there are plenty of labs back on earth trying to perfect the anti-gravity bike…
Given the modern interest in finding life on other planets, I would think that finding signs of life should be reasonably easy. Finding actual people should be difficult, but houses, even very basic ones, should stand out. Fires would also stand out for both heat and smoke. Agriculture tends to create very obvious. If someone takes a boat out on the water, that will stand out, though submarines might be difficult. Even very small boats should be easily detectable. If they can capture motion on their sensors, detecting people should be much easier too, because I think people tend to stay more visible in the visible spectrum than animals do.
Given the similarities between this planet and Earth, any type of positioning system is probably extremely easy to set up and very accurate. My biggest concern for GPS systems is what coordinate systems they are using. Modern coordinate systems are based heavily around complicated models of the Earth. For an unknown planet however, I would want to use a raw (Geocentric Coordinate System) coordinate system. This minimizes coordinate conversions and assumptions about the planet. It also makes it more difficult for the people on the ground to communicate, calculate distances, and create a frame of reference for nearby locations.
As far as what we don’t know, I would include things below the surface and below the water. If someone knows about ground penetrating radar, they might be able to weigh in on that. I think that would need to be used locally because it needs to be used close to the surface. Water would be easier, but you usually want to look deeper.
Looking at history would be another problem. They can observe the current status, but they can’t see what happened the day before unless it is still going on.
A planet with a lot of life is a lot more complex then a barren one. You can look at ecological changes with plant and animal life and spend years analyzing just that. Meteorological changes would be very interesting too. All of this affects their ability to look into the past.
Basing their GPS data on a tech-level equivalent Google Earth re-applied to the ‘para-earth’ could greatly reduce their need for low level satellites so i still think localized data relays are all that would be needed. An I admit that i completely missed the fact that they had faux-grav. Tech is substantially higher than i assumed: FTL transit experimentation, gravity on command, multi-planet colonization, and a host of other things i am just now realizing. It is almost at the point where it could be written off, but i really do appreciate that you ARE thinking of the little things and working on them. Anti-grav drones could not only serve as data relays and personnel locators for the away team, but could be their surface to ship transit system as well.
Bio-scanners can be kinda assumed by this point, at least at the level of analyzing air samples for deadly pathogens, radiation, and habitability. I reference larger units like The Mars Rover, or Stargate’s MALPs as the basis of the design.
The current radar satellites have a resolution of 1m, focused on an area of 6 x 6 km. Rumors of military sats with 0,2m resolution exist. The resolution is proportional to the covered area.
Each material reflects different on different radar wavelengths. On false-color images metal and water are easy spot able. Via Doppler Effect and good computers you can auto detect every moving object. Animals and human bodies are moving water. Additionally the picture is 3D with height information.
With antigrav drives you could get a much better resolution, because the orbiting (movement) and the minimum orbit height of the satellite is a problem.
Stationary satellite/drones with integrated radar and GPS transmitter would be perfect for local navigation and real time surveillance.
Let’s assume no human without high-tech camouflage could come closer than 5km, no car can get closer than 50km and no plane closer than 500km, without detection.
TerraSAR-X pictures: http://www.dlr.de/en/desktopdefault.aspx/tabid-4313/6950_read-10126/
Just a small thought: if I was the creator of this comic (which I’m not – I just wish I was… ^_^) I’d probably put a kibosh on the antigrav drones.
My reasons?
1. Just from what little I know about the physics, I’d expect any believable antigravity or artificial gravity system would be power-hungry. Ships could supply the needed energy easily enough, but for something as small as a laptop or smaller? Can’t see it – not without introducing enough magical technology into the mix that many of the problems that would make Galaxion interesting would be nonproblems. Beware the Perfect Technology…
2. Advanced does not always mean superior, or cheaper. Keeping antigrav drones in working order would be tougher / more expensive than keeping balloons, rovers, or UAVs in working order. By the era of the Galaxioverse, I’d expect that balloons, rovers, and UAVs to be so cheap and easy that they’d almost be disposable (I’d rather lose a $1 calculator than a $1,000 computer…)
That’s my two cents on antigrav drones, for what it’s worth.
There is a ton of information that can be gathered from orbit with a good set of sensors.
from a physics perspective there isn’t a whole lot different between visible light, x-rays, infrared radiation, ultraviolet light etc. They are all photons, and hence have the wonderfulness of particle-wave duality going on for them (i.e. they will diffract like a wave, but have some mass like a particle). The difference is only the energy of the individual photons. A large number of semi-conductors can be used to detect photons of differing wavelengths, so there is no reason why the Galaxion would not have a fairly full spectrum image of the planet.
The main utility of different wavelengths of light is that they are produced in different ways, by different processes. If you saw hot spots of short wavelengths like x-rays or gamma rays, or really long wavelengths like radio waves that might be indicative of life (or it might just be some natural cluster of radioactive material). As for infrared, you wouldn’t really be able to see people inside buildings, however the buildings and cities themselves would show up on infrared even if they were abandoned, although they would be harder to find if they were now covered in jungle. In this case you’d probably be looking for either dark or light spots with sharp defined borders as buildings tend to be much more angular with well defined borders than natural formations, and would likely differ quite substantially in what they were made out of. Of course if the people on the planet all live in adobe huts, those might blend in much better with the surrounding terrain and would be much more difficult to pin point.
-S
What I know about particle physics would probably neatly fill a Mr. Men book, but with regard to your query, “Can they see inside the Hiawatha?” it would seem reasonable to assume anything built by Tersa is resistant to EM radiation at least as powerful as any of their directed sensor beams are likely to be from orbit.
I only just started reading this comic (I love it, by the way), so sorry if this is a bit late to help!
I’m an atmospheric science PhD student, with a BA is Geology, so remote sensing is something I’ve been involved with quite a bit.
There’s a lot of good stuff already here (looking at the nasa info is especially good), so I’ll just say a couple of things in a nutshell:
A) There is an incredible amount of information that can be gained on surface and the atmosphere of the planet. If you have an instrument which can emit in mutliple wavelengths (or multiple instruments) you can find out about the chemical composition and dynamics of virtually any layer of the atmosphere (with higher reliability for the composition). Changing wavelengths is key, because different things absorb/emit at different wavelengths. The higher atmosphere will be better than the surface, but since we are beginning now to be able to see the surface layers with some degree of accuracy, in 200 years you should be fine.
B) Buildings would probably cause the greatest amount of hinderance, especially the ship because of radiation shielding and the probable density of the building materials. For any electromagnetic sensing, the more dense the material, the smaller the depth that can be “seen” through. Underground could be probematic for the same reason, depending on how deep they are.
To simply detect movement/lack thereof or simple characteristics of the space, theoretically it would be possible to put an instrument sensitive to vibrations/sound on the surface of the building, which could transmit electromagnetic pulses back to the ship. It would have to be very sensitive (and therefore prone to noise) to pick up details of what is happening inside. For actual mapping of inside the structure, two or more instruments on the surface of the cave/building/ship would be needed.
I hope that helps. Feel free to ask questions on specifics.
-Cassie
You might wish to look into terahertz sensing (using waaay far infrared, i.e. sub-micron infrared wavelengths). There are, as of yet, no good sensors (beyond wide range bolometers) in this range, but a lot of research is going on about both coherently creating and detecting terahertz radiation. There were Science and Nature articles on the topic a couple of years ago. Google Terahertz sensing and skim through.
One point to note is that detecting the presence of a signal and detecting its wavelength (i.e., color) are very different concepts (check the difference between ‘bolometers’ and other semiconductor based infrared sensors). Also, detecting a signal does not immediately imply that you can get an ‘image’. For an image, you need many sensors and be able to light them up separately. But given a good terahertz sensor and a bit of sci-fi, that wouldn’t be a problem.
Oh, and if you need ‘technobabblish’ words that are not made up, here are a couple for you:
Hot electron bolometers
Superconducting transition edge bolometers/sensors (That even makes a decent acronym: STES )
In terms of what they will not know:
Orbital technologies that can detect a human on the surface are pretty likely, but this is in terms of detecting that there is something where the human is. This is not the same as detecting that there is a human there, much less which human it is. The useful dramatic limitation is that technologies that can distinguish one moving blob of hot water a meter in diameter (not a bad model for a human without any material tech on their person) from another (say a deer) are much harder. The more human like things there are in the landscape, and the more human like they are, the harder the problem becomes.
Finding a human that you know is there in a snow field is easy. Finding a human you don’t know is there is in a geothermal area is less easy. Noticing a human in a forest full of deer would be hard, Noticing a human that you did not already know was there in a building full of apes that are playing with bits of metal left over from an extinct civilization could be impossible.
In A Nut Shell>
Using the entire range of the electromagnetic spectrum from very low frequency (VLF) right through to Ultra violet you can interrogate just about anything as long as you have the ability to understand the information that is returned by your equipment. You see different wavelengths react differently to different matter. This includes the characteristic of certain frequencies to penetrate/conduct for miles through matter aswell.
See also GasChromatoghraphy http://en.wikipedia.org/wiki/Gas_chromatography
(Electronics tech married to a forensic scientist)
Better references>
http://en.wikipedia.org/wiki/Spectrum_analysis
http://en.wikipedia.org/wiki/Photo-ionization_detector
6 months later…still some input!!!
Given that they are still on the surface and still want to scan things from orbit, it should still be reasonably useful.
Military spy-satelites TODAY can read the license plate off of a car. Given the amount of technological advancement in this story, I’m certain that a good scanner would be able to read a book over your shoulder from orbit. The ship, simply put, has an aerial view of everything going on on the ground. With the optics necessary to examine stellar objects, you could easily turn them planet-side and get a mighty-fine view of the surface.
So in summary, you are in NO danger at all of exceeding reasonable surface-detection capabilities given what you may or may not want for the plot. Geostationary orbit is at an altitude of 36,000km which is less than 1/10th the distance of the moon, and our ground-based telescopes can get a pretty darned good picture of that. For futuristic telescopes IN SPACE!!!(R), you should certainly be able to detect people walking about on the surface…assuming you knew where to look. Which they do.
Interesting comments above- lots of intelligence !
Just a few comments.
A survey would mean some kind of map. All maps are started from some reference-point, called a “bench mark” for standard Terrestrial mapping, that is essentialy the zero-point of the map. Someplace would stick out in their initial survey that would be designated as the initial starting point for the map, from which all coordinates would follow. Their hand-helds might have a mostly blank map of the planet (that would be constantly updated) but the region they were interested in would be reduced to workable coordinates for speed and ease of use.
From orbit with their cameras, (and more than likely a lens that in effect would be the size of the ship) they would have the resolution be able to see almost anything. People would be the easiest, because they leave trails and marks wherever they go. Any settlement would be surrounded by clearings for housing, roads, refuse and the other signs of habitation like smoke, factories, radio-stations would be easy to see. But if there has been a war or some kind of disaster people and their signs might be more hidden. Their analysis would show perhaps old cities but the people would have taken refuge in more strategic locations, like underground, and be much more difficult to observe.