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Comment: Re:Larger landing area (Score 1) 342 342

That would be hot for an aircraft, but it was the planned vertical speed profile for the rocket.

Wasn't it supposed to land at 5m/s? First stage is about 37m tall and it should take leisurely 5 - 6 seconds or so to finish the last rocket length, but in the video, it is finishing that in about 2.5 - 3 sec, coming in at least twice as too hot. Maybe they need to start the landing thrust several seconds earlier, assuming they have enough fuel left.

Comment: Not in place???? (Score 2) 234 234

a new scan technique using muons have shown the fuel is not in its place.

Hah??? The whole point of this technology was supposed to be able to locate where the fuels debris are so they can start planning the removal. They said it themselves.

http://www.tepco.co.jp/en/pres...

But before those reactor cores can be removed, it is essential to locate where the debris has dropped inside the reactor.

So the technology didn't work. They just confirmed that the it is not in the core, which provide them with zero information to be able to move forward but they didn't say that and pretending it is some kind of achievement and not admitting the fact the they didn't achieve the prime objective of this exercise. Very typical of TEPCO. I hope they don't waste money repeating this to #2 and #3 to confirm that the fuels are not in place there either.

Comment: Lots more details (Score 2) 53 53

Lots more details describe in this article: DSCOVR Mission Updates. One interesting information is that landing burn in only 28 seconds. That's all it takes to slow down from the terminal velocity down to 0 while performing the final guiding maneuver to the bulls eye.

Comment: Re:Intriguing, but landing at launch site? (Score 3, Informative) 53 53

fly all the way back to the launch site (would seem to be alot of fuel) -

That was my original impression, that you have to continuously burning to actively control the fall. But I recently saw a number that Apollo style capsul's terminal velocity is something around 300 miles/h and they spend several minutes free falling after fireball decelleration. Note "free falling" in this context is different from physical definition of free falling and describe the falling at constant speed of terminal velocity. 300 miles/h is half as fast as horizontal speed of airliners, and comparing to 120 miles/h of skydiving of human body (I'm a skydiver), it is not very fast. So after the supersonic reentry, I assume first stage is already on the trajectory to free fall toward the landing pad only controlled by the fins without any fuel burn. I'm curious what is the terminal velocity of the falcon 9 first stage is, but with empty large volume with little fuel left, and engine cones facing down, I imagine it is not that fast. This phase of landing is abbreviated in their fancy CG, so I too also got impression that they burn fuel from pretty high up, but we also saw one chase plane video of first stage coming down through the clouds without burning any fuel and seems to be in stable free falling.

Programming

Introducing Children to Computers? 886 886

Years ago, kids could be gradually introduced to computers through learning languages like LOGO and educational computer games. Many of us started our computing careers at our parent's workplace, logged in to a word processor to type away, only to become fascinated with the whole computing thing. So Slashdot, let's hear how you were lured into the digital life. What was it that drew you to a life of programming? How old were you when you first used a computer? What pieces of modern software do you think would be a good way to introduce today's kids to the world of computing?

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