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Comment Re:Maybe the driver believed it was enabled? (Score 1) 166

Auto-pilot comes from aeroplanes, where it is a device that keeps the plane in straight and level flight. It will happily maintain altitude and heading all the way into a mountainside. Really advanced ones even sqwark at you before impact; They all are set to throw their hands in the air and hand the plane back to the human pilot, without prior warning, if things go wrong. Very much like the Tesla's. So, when a system that can control the car without human attention is developed, then it won't be called 'auto-pilot'.

Comment Re:Maybe the driver believed it was enabled? (Score 5, Interesting) 166

Possibly the driver, seeing the bridge or rail coming up and being uncomfortable with the approach speed, tapped the brake. This would have disabled the autopilot.

Now, although disabling automatic systems on manual input has been the standard for as long as automatic systems have been available, I am beginning to wonder if it really is the right decision here. People seem to be turning it off without realising that they have done it.

Comment Worse than that: this spacecraft has broken up. (Score 4, Informative) 77

Sourced from the competition of things you may have read: :

Oh this is very very bad. From @spacetrackorg "Breakup Notification: [...] ASTRO H at approx 0820z, 26 Mar 16: 5 associated pieces .."

Suspected causes are a MMOD hit, battery explosion or cryo system overpressure. Suggestoin that "It's too early to write the satellite's obituary", but any good news is very unlikely.

Comment For a real DCMA notice, a real lawyer signs. (Score 2) 157

Notionally, that lawyer is responsible for the notice. But the law has a 'good faith' provision, that clears the lawyer if the notice was issued in good faith. As everyone is interpreting that 'the computer told me to put it on the notice, I didn't check anything' as 'good faith', the penalties in the act have no effect.

If only web sites were keeping track of videos like these as 'canaries', and automatically rejecting as invalid any notices that include them. A notice that includes a video that is so clearly not infringing could not be considered 'valid'.

Comment Re:Destructive test does not mean 'blow it up'. (Score 1) 373

OK, I see - the person you replied to mis-used the term 'destructive testing' to mean repeatedly launching the rocket until it destroys itself. Yeah, that would not be competent, and would tell them nothing.

Real destructive testing is used all the time. SpaceX themselves would destructively test a sample of every part they buy, or build. Parts of this rocket will be destructively tested to confirm what their models tell them. But you knew that.

Comment It is CRS-4, which soft-landed in the ocean. (Score 3, Informative) 20

The mission this piece came off was CRS-4. This mission was one of the first missions where recovery experiments were done.

After separating from the second stage and payload, this first stage was spun around, the engines re-lit to slow the rocket down and allow it to re-enter the atmosphere on one piece. It then fell through the atmosphere, before the engines re-lit a third time to slow it down, and it splashed down at slow speed. At this point, the stage would have fallen over, and the pressurized tanks would have burst.

A good run down of the landing attempts are on a page in the reddit spacex wiki at

They identified that this was from this stage by eliminating all others.

It wasn't from the rocket that exploded, because that rocket had grid fins added, and the location where these fins would have been is on this piece of debris. In addition, not enough time has passed for debris from that event to have reached the Isles of Scilly. This also rules out any recent launch, for the same two reasons. It would also be assumed that the destruction of CRS-7 would have caused more damage to this piece than we see.

Of the other launches, they ruled out early ones because the designs of the flag and logo didn't match, and that they would have been destroyed by reentry as you said. That left about 5.

They then compared images of the rockets on the launch pad with the images of this debris. The locations of items (lumps and bumps, basically) on the interstage only matched for one launcher: the launcher for CRS-4.

Once this was confirmed, it matched with a serial number located on the stage. Earlier this year, a piece of the fairing from another launch was found washed up in the Caribbean. It had a similar serial number on it. SpaceX quickly confirmed what launch it was from, and it was noted that the 'core number', that is, sort of the serial number for the whole rocket, was embedded in a particular place in that part's serial number. In the same place in this piece's serial number was the correct core number for CRS-4. So they had their answer. All we are waiting for is SpaceX's confirmation, which should come in the next few days.

Comment Re:Data data everywhere and not a drop to think (Score 1) 366

Oh, don't forget - 5. 'won't break'. And 6. 'Doesn't weigh too much'.

A load cell (or strain gauge) is a device that flexes depending on how much force is on it. They want to put this between the wheels and the suspension, and leave it there to take the impact forces of landing. It would only be a matter of time before one of these would develop metal fatigue, snaps during a heavy landing, and kill a plane-load of passengers.

Comment Re:It's always Stage III (Score 4, Interesting) 72

That is really not that surprising. All the design constraints in rocketry really come to a head in the last stages. Every kilogram of mass in your last stage is a kilogram less payload you can carry, and it is where you really need the most efficiency, the peak isp, so you want to push the pressures and temperatures as high as you can.

As light as you can make it, as powerful as you can make it. This leads to fine tolerances and making the design only as strong as it needs to be.

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