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Pseudo-satellites: A cheap alternative to satellites is starting to take off

115 点作者 klearvue超过 10 年前

10 条评论

btown超过 10 年前
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:<p>&gt; 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 &quot;Kessler syndrome&quot;, 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]<p>(Anyone remember that scene from WALL-E where they need to punch through the debris to get out of Earth&#x27;s orbit? It&#x27;s not too far from the truth, and it would definitely make space travel a lot more difficult for future generations!)<p>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.<p>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!<p>[1] <a href="http://en.wikipedia.org/wiki/Space_debris" rel="nofollow">http:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Space_debris</a>
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electromagnetic超过 10 年前
I wonder what the lower weight limit is on these. The solar panels produce 1kw&#x2F;kg the batteries store 350 watts per kg. The whole thing weighs 50kg and has a 23m wingspan.<p>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&#x2F;kg.<p>Basically we could have done this in the 1960s with a payload of about 80-120kg of equipment.<p>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&#x27;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.
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fensterbrett超过 10 年前
How do they compare with Google Loon?<p><a href="http://www.google.de/loon/" rel="nofollow">http:&#x2F;&#x2F;www.google.de&#x2F;loon&#x2F;</a>
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trhway超过 10 年前
one of the things that really can be resolved by technology here is re-fueling in air. You don&#x27;t need solar panels and batteries if your drone hanging at 20km can be automatically supplied by refueling missions of another drone.<p>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&#x2F;week.
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qwerta超过 10 年前
NASA patfinder has been around for some time already: <a href="https://en.wikipedia.org/wiki/NASA_Pathfinder" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;NASA_Pathfinder</a>
jessriedel超过 10 年前
Why is this better than a balloon? (Most use cases don&#x27;t need maneuverability, which usually isn&#x27;t possible with satellites either.)
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nkozyra超过 10 年前
Missed opportunity at &quot;pseudollite&quot;
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mturmon超过 10 年前
Hmm, an un-crewed airplane for remote sensing applications:<p><a href="http://uavsar.jpl.nasa.gov" rel="nofollow">http:&#x2F;&#x2F;uavsar.jpl.nasa.gov</a><p><a href="https://airbornescience.nasa.gov/aircraft/SIERRA" rel="nofollow">https:&#x2F;&#x2F;airbornescience.nasa.gov&#x2F;aircraft&#x2F;SIERRA</a>
nothiggs超过 10 年前
As for using it for military purposes - wouldn&#x27;t any country it flies over that has the ability to detect it, just shoot it down?
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nlkndlk超过 10 年前
&gt;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.<p>&gt;If spacecraft are so precarious, then perhaps investors should lower their sights. But not in terms of innovation; rather in altitude.<p>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&#x27;re never going to become a interplanetary, space-faring civilization under this current economic system.
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