If a network of these aircraft becomes a viable alternative to satellites, this could be a partial solution to the imminent problem of growing space debris, whose quantity and danger posed are decidedly super-linear to the number of objects launched into space:
> As the chance of collision is influenced by the number of objects in space, there is a critical density where the creation of new debris is theorized to occur faster than the various natural forces remove them. Beyond this point, a runaway chain reaction may occur that would rapidly increase the number of debris objects in orbit, and therefore greatly increase the risk to operational satellites. Called the "Kessler syndrome", there is debate if the critical density has already been reached in certain orbital bands. A runaway Kessler syndrome would render a portion of the useful polar-orbiting bands difficult to use, and greatly increase cost of space launches and missions. Measurement, growth mitigation and active removal of space debris are activities within the space industry today. [1]
(Anyone remember that scene from WALL-E where they need to punch through the debris to get out of Earth's orbit? It's not too far from the truth, and it would definitely make space travel a lot more difficult for future generations!)
On the other hand, an alternative to satellites for private industry means that there will be a lower demand curve for commercial launches, which may limit the amount of research and innovation that private space companies can support.
But of course Earthlings, in their infinite wisdom, have found a solution to low demand curves: government regulation! So the real question is: can our governments find a good balance between debris-proliferation and innovation? Only time and politics will tell!
Relatively low flying satellites are also a solution space debris as they only stay up a few years. The are much cheaper to launch so the fact that they don't last as long is not prohibitive.
I wonder what the lower weight limit is on these. The solar panels produce 1kw/kg the batteries store 350 watts per kg. The whole thing weighs 50kg and has a 23m wingspan.
Training gliders weigh about 600kg, and they have a 41kw gas engine to self propel and have a wingspan of 18m (based on the one linked on the wikipedia article). Average weight is about 80kg for a male. So these can likely get 160-200kg airborne with ease. RTGs produce about 500w/kg.
Basically we could have done this in the 1960s with a payload of about 80-120kg of equipment.
I wish we could get over our fear of nuclear. It would be very easy and efficient to build one of these with an RTG and you would have the ability to include redundancies and even in the event of engine failure you're not at risk of losing equipment and it can be glided to land. It could also carry its own landing gear and you could automate take off and landing schedules so you need minimal overlap on craft. One goes up to take the place while another gets serviced. With redundancies you could keep them flying with a fixed pitch for potentially years.
I agree, but hundreds of nuclear power sources hovering around the planet controlled by a single corporation ... sounds like the plot of a James Bond movie.
Note that the batteries do not store 350 W/kg, but 350 Wh/kg. That means the majority of weight is batteries, since you need 1 kg/kW for the day but 1 kg/kW + 12 h * 1 kg / 350 Wh for the night, giving a total of 36.3 kg/kW of continuous power. The article implied that these things could not store enough power for the nighttime, which is easy to believe from those numbers.
An RTG at 2 kg/kW would be so ridiculously good value that it makes you wonder what has changed about aviation drones to make this viable only now. Is it really just the radiation thing?
one of the things that really can be resolved by technology here is re-fueling in air. You don't need solar panels and batteries if your drone hanging at 20km can be automatically supplied by refueling missions of another drone.
Say 40kg of batteries would contain 14KWh, ie. equivalent of 1.5 liter of gas or with adjustment for the thermodynamic efficiency of a gas turbine - 4 liter. Thus
30kg (lets allocate 10kg for the gas turbine and other stuff) of gasoline is a 10 day supply of fuel. Thus your re-fueling drone would need to make 1 trip/week.
But if you can build a drone that can stay up nearly indefinitely, why bother refueling it?
Would it make more sense to perpetually spend money on fuel (and the fuel it takes to launch the fuel), or to spend more money up front to design a robust HARP that only comes down in case of severe fault, and is cheap enough that it's easier to just replace it?
The main uses for satellites are observation and communication. Both are appealing markets for HAPS. Hovering drones could act as relays for telephone calls and internet traffic in places that do not have good enough infrastructure on the ground. And there is never a shortage of customers who would like to snoop on various parts of the Earth’s surface, whether for commercial or military reasons.(fta)
If your enemy is a national government, yes. But we're at the stage now where national governments should know better than to get into fights with each other. Unless the recent idiocy between America and Russia gets out of hand, likely enemies in the near future are nonstate actors like ISIS who would have difficulty shooting down something at that altitude.
>That Arianespace, a French rival of SpaceX, announced on the same day that two satellites it had tried to launch to join the European Space Agency’s Galileo constellation (intended to rival America’s Global Positioning System), had entered a “non-nominal injection orbit”—in other words, gone wrong—shows just how difficult the commercialisation of space can be.
>If spacecraft are so precarious, then perhaps investors should lower their sights. But not in terms of innovation; rather in altitude.
As if constraining ourselves to low-earth orbit were too ambitious. It is absolutely disgusting to suggest that, after we gutted NASA in order to make opportunities for private enterprise, we should just stop sending stuff to space altogether. We need to face it: we're never going to become a interplanetary, space-faring civilization under this current economic system.
> It is absolutely disgusting to suggest that, after we gutted NASA in order to make opportunities for private enterprise, we should just stop sending stuff to space altogether.
I do not think that was the point of the article. Some things do not absolutely need to be beyond the atmosphere, they only need to be up high. In the past, the technology to keep things at what might be termed "moderate" altitudes has not been available, so we pushed things above the atmosphere. But when you have technology to do the job better, it does not make sense to continue sending things up to space simply because that is what has been done in the past.
Not to mention, retrievable technology means it can be upgraded, rather than junked (as many satellites are). So this could very well reduce space junk (or at least reduce its rate of increase) and result in more rapid technology development.
There are certainly there are things which will still be easier or better served by the use of satellites up, and so that technology will continue to be developed.
Never is a really long time. Even if we make 0 investment in space travel, we will almost certainly be better equipped for space travel than we are today. The only possible exceptions to this that I can think of are: modern civilization collapsing (or some less extreme variant) or us having depleted some critical resource.
Lofting stuff up into space 'just because' rather than because it meets some technological or economic need is a waste of time. I am very much in favor of becoming a spacefaring civilization and will cheerfully argue for the necessity of manned missions despite the availability of robots and so on. But wasting money on putting things into space is counter productive to that end.
This has nothing to do with our economic system. It's basic economics, in the sense that it's resource-intensive to put stuff into space and some resources are scarce. Regardless of how your domestic economy is organized or what sort of monetary policy you favor, the physical resources required for space projects are steep.
> we're never going to become a interplanetary, space-faring civilization under this current economic system.
I disagree. Just look at SpaceX's development of reusable rockets. We are closer than ever before to becoming interplanetary [OK, that's basically a tautology] and developing space technology faster than any point after landing on the moon.
Well... almost as much as the NASA being a rival of SpaceX, Arianespace being the French/European initiative for space access. Arianespace was founded in 1980 to commercialize the Ariane launcher (planned in 1973 after the europa launcher failure).
btown|11 years ago
> As the chance of collision is influenced by the number of objects in space, there is a critical density where the creation of new debris is theorized to occur faster than the various natural forces remove them. Beyond this point, a runaway chain reaction may occur that would rapidly increase the number of debris objects in orbit, and therefore greatly increase the risk to operational satellites. Called the "Kessler syndrome", there is debate if the critical density has already been reached in certain orbital bands. A runaway Kessler syndrome would render a portion of the useful polar-orbiting bands difficult to use, and greatly increase cost of space launches and missions. Measurement, growth mitigation and active removal of space debris are activities within the space industry today. [1]
(Anyone remember that scene from WALL-E where they need to punch through the debris to get out of Earth's orbit? It's not too far from the truth, and it would definitely make space travel a lot more difficult for future generations!)
On the other hand, an alternative to satellites for private industry means that there will be a lower demand curve for commercial launches, which may limit the amount of research and innovation that private space companies can support.
But of course Earthlings, in their infinite wisdom, have found a solution to low demand curves: government regulation! So the real question is: can our governments find a good balance between debris-proliferation and innovation? Only time and politics will tell!
[1] http://en.wikipedia.org/wiki/Space_debris
seanflyon|11 years ago
electromagnetic|11 years ago
Training gliders weigh about 600kg, and they have a 41kw gas engine to self propel and have a wingspan of 18m (based on the one linked on the wikipedia article). Average weight is about 80kg for a male. So these can likely get 160-200kg airborne with ease. RTGs produce about 500w/kg.
Basically we could have done this in the 1960s with a payload of about 80-120kg of equipment.
I wish we could get over our fear of nuclear. It would be very easy and efficient to build one of these with an RTG and you would have the ability to include redundancies and even in the event of engine failure you're not at risk of losing equipment and it can be glided to land. It could also carry its own landing gear and you could automate take off and landing schedules so you need minimal overlap on craft. One goes up to take the place while another gets serviced. With redundancies you could keep them flying with a fixed pitch for potentially years.
damian2000|11 years ago
sesqu|11 years ago
An RTG at 2 kg/kW would be so ridiculously good value that it makes you wonder what has changed about aviation drones to make this viable only now. Is it really just the radiation thing?
fensterbrett|11 years ago
http://www.google.de/loon/
seanflyon|11 years ago
trhway|11 years ago
Say 40kg of batteries would contain 14KWh, ie. equivalent of 1.5 liter of gas or with adjustment for the thermodynamic efficiency of a gas turbine - 4 liter. Thus 30kg (lets allocate 10kg for the gas turbine and other stuff) of gasoline is a 10 day supply of fuel. Thus your re-fueling drone would need to make 1 trip/week.
pavel_lishin|11 years ago
Would it make more sense to perpetually spend money on fuel (and the fuel it takes to launch the fuel), or to spend more money up front to design a robust HARP that only comes down in case of severe fault, and is cheap enough that it's easier to just replace it?
qwerta|11 years ago
jessriedel|11 years ago
neolefty|11 years ago
winfred|11 years ago
nkozyra|11 years ago
emddudley|11 years ago
http://en.wikipedia.org/wiki/Pseudolite
TeMPOraL|11 years ago
mturmon|11 years ago
http://uavsar.jpl.nasa.gov
https://airbornescience.nasa.gov/aircraft/SIERRA
nothiggs|11 years ago
rwallace|11 years ago
seanflyon|11 years ago
nlkndlk|11 years ago
>If spacecraft are so precarious, then perhaps investors should lower their sights. But not in terms of innovation; rather in altitude.
As if constraining ourselves to low-earth orbit were too ambitious. It is absolutely disgusting to suggest that, after we gutted NASA in order to make opportunities for private enterprise, we should just stop sending stuff to space altogether. We need to face it: we're never going to become a interplanetary, space-faring civilization under this current economic system.
privong|11 years ago
I do not think that was the point of the article. Some things do not absolutely need to be beyond the atmosphere, they only need to be up high. In the past, the technology to keep things at what might be termed "moderate" altitudes has not been available, so we pushed things above the atmosphere. But when you have technology to do the job better, it does not make sense to continue sending things up to space simply because that is what has been done in the past.
Not to mention, retrievable technology means it can be upgraded, rather than junked (as many satellites are). So this could very well reduce space junk (or at least reduce its rate of increase) and result in more rapid technology development.
There are certainly there are things which will still be easier or better served by the use of satellites up, and so that technology will continue to be developed.
spindritf|11 years ago
http://scottlocklin.wordpress.com/2011/07/22/good-riddance-t...
gizmo686|11 years ago
anigbrowl|11 years ago
This has nothing to do with our economic system. It's basic economics, in the sense that it's resource-intensive to put stuff into space and some resources are scarce. Regardless of how your domestic economy is organized or what sort of monetary policy you favor, the physical resources required for space projects are steep.
seanflyon|11 years ago
I disagree. Just look at SpaceX's development of reusable rockets. We are closer than ever before to becoming interplanetary [OK, that's basically a tautology] and developing space technology faster than any point after landing on the moon.
blaze33|11 years ago
Well... almost as much as the NASA being a rival of SpaceX, Arianespace being the French/European initiative for space access. Arianespace was founded in 1980 to commercialize the Ariane launcher (planned in 1973 after the europa launcher failure).
alexvr|11 years ago