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SpaceX Launch of "GoreSat" Planned For Today, Along With Another Landing Attempt
The New York Times reports that SpaceX will again attempt to recover a Falcon 9 launch vehicle, after the recent unsuccessful try; the company believes the lessons from the earlier launch have been learned, and today's launch will be loaded with more hydraulic fluid. This evening, the rocket is to loft the satellite nicknamed "GoreSat," after Al Gore, who envisioned it as a sort of permanent eye in space beaing back pictures of Earth from afar. The purpose of the satellite has evolved, though: Writes the Times: The observatory, abbreviated as Dscovr and pronounced “discover,” is to serve as a sentinel for solar storms: bursts of high-energy particles originating from the sun. The particles from a gargantuan solar storm could induce electrical currents that might overwhelm the world’s power grids, possibly causing continent-wide blackouts. Even a 15-minute warning could let power companies take actions to limit damage.
The Falcon 9 is made up of two parts: a 138-foot-tall first stage, which burns for the first few minutes of flight, lifting the craft up to an altitude of about 50 miles before separating and falling back to Earth, and a smaller, 49-foot-tall second stage, which burns for another five minutes or so, carrying the spacecraft into orbit before disconnecting and falling back down to earth as well.
Normally, both of these stages — as well as the stages that make up other rockets in general — break up into pieces as they plummet downward, eventually sinking in the ocean and becoming unusable. But on Sunday, as the first stage falls back to earth, SpaceX will fire its engines in order to stabilize and guide it in for a controlled landing.
The plan is to land it on an autonomous uncrewed barge, which is being stationed about 370 miles east of Cape Canaveral. As the rocket descends, steerable fins affixed to its outside will help guide it and slow it down. As it nears the barge, a set of legs will unfold from the bottom of the rocket, and if all goes to plan, it'll slow down to a speed of about 4.5 miles per hour before gently landing on them, fully upright.
To solve the problem from the last attempt, the rocket will be carrying more hydraulic fluid.
http://www.vox.com/2015/2/8/79...
It was nicknamed Goresat by it's detractors for two reasons. One of the primary payloads is designed to monitor albedo, which is there to support global climate research. A secondary payload is a camera, supposedly requested by Gore. The camera was to provide high definition, continuous real-time imagery of the entire Earth -- a full sunlit globe. The Wikipedia description matches my memory of the debate: " Gore hoped not only to advance science with these images, but also to raise awareness of the Earth itself, updating the influential The Blue Marble photograph taken by Apollo 17"
This one's orbit is high enough to encompass Gore's monumental ego.
The imagery was supposed to be live streamed to the internet, for one thing. Most of the climate or weather satellites are in Earth orbit, between 350 and 23,000 miles up. This will be all the way out at L1. Being at L1, there will always be a sunlit Earth image and you'll always see the a full hemisphere. Don't know that it will actually end up implemented like that, but that was the intent.
At this point, the pull from the earth will cancel out the pull from the sun, and the satellite will effectively stay positioned exactly between the earth and sun as the earth rotates around.
Not quite. From NASA:
The Lagrange Points are positions where the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them.
Lagrangian Point 1 (L1) is located on the line between the Earth and the Sun. At L1, the opposing gravitational force from the Earth partially cancels the force from the Sun, reducing the overall centripetal force. In orbital mechanics, the periods of Sun orbiting objects increase with increasing radius, due to the decreasing gravitational force (lower force, lower acceleration, lower speed, increasing circumference). Because the satellite at L1 feels a weaker centripital force than it would normally experience at that solar orbital radius, it can orbit the Sun at a period of 365.25 days, in spite of being closer to the Sun than the Earth. Thus it maintains its relative position between the Sun and the Earth.
This and no other is the root from which a tyrant springs; when first he appears as a protector - Plato (423 to 327 BC)
The Earth-Sun L1 point is 1.5 Gm from the Earth, pretty much exactly 1% of the distance from the earth to the sun. So to fully cover the sun (as seen from one spot on Earth), the blind would have to be 1% of the Radius of the sun. That's basically the radius of the Earth, or 4 times the radius of the Moon. To cover the sun as seen from anywhere on Earth, you would need a slightly bigger radius due to perspective.
But one doesn't need to cover the whole sun (unless one wants to play the grandparent's nefarious games with Asia). A 1% reduction in insolation would already help a lot. So that gives us about 1% of the area of the earth, or 1.5e12 m^2. With graphene's density, that works out to be 1,120,000 kg for a single layer. For comparison, the international space station's mass is 450,000 kg, so that mass is within the realm of the possible to launch, even to the much greater distance of L1.
But a single layer of graphene is transparent, which isn't a good quality to have for blocking the sun. So much more than 1 layer would be needed. That would very quickly bring the mass into unrealistically high levels, corresponding to hundreds or thousands of space stations. And that still ignores the mass of the supports needed to keep the graphene extended and in the right shape, which would probably weigh more than the graphene itself.
Another problem inherent to such a large surface area is that the solar wind will exert a pretty large force on it. The solar wind has a pressure of about 4nPa, which multiplied with the huge surface area gives a force of 6 kN towards the Earth. So a rockets would have to be mounted on it to keep it in orbit. Or actually, one can compensate for this force by moving solar sail blind closer to the sun, where it would be able to orbit with the same angular velocity as the Earth without any correcing rockets on average. However, the solar wind isn't constant, so it would still need corrective rockets. And it would be in the way for all the current sun-observing satellites at L1. There would also be a tendency for the blind to rotate to show its thin direction to the solar wind, which would need to be counteracted.
This could probably be done, but I it would probably be by far the largest project ever attempted, and much more expensive than other, simpler ways of dealing with global warming, such as polluting less. It's a fun idea, though.