Posted on 04/18/2015 3:17:33 PM PDT by BenLurkin
Most rocket boosters either burn up in the atmosphere or – as NASA’s do – simply fall into the ocean. With cheaper spaceflight the ultimate goal, SpaceX is the first space organization to attempt a rocket landing on a floating base, or, as the company calls it, an “autonomous spaceport drone ship.” Still, it begs the question- why attempt the landing at sea?
According to American Institute of Aeronautics and Astronautics Aerospace Engineer Paul Huter, it’s simply a matter of convenience. “The rocket is launching out over the Atlantic ocean, so the easiest place to land it would be straight out into the ocean. Now, obviously, this presents challenges when compared to landing [a rocket] on solid ground as something at sea is constantly moving around. But in terms of energy required (most of which has already been used during the launch), it is more efficient to try and land on something in the ocean.”
As for whether or not the deep-pocketed space organization can successfully land the rocket, some experts are dubious. Even before the latest landing attempt, Musk himself was giving it a 50/50 chance to succeed. Huter believes SpaceX can pull it off, but it won’t be anytime in the near future. “I think SpaceX has the capability and the know-how to land on the floating barge, but there are a lot of variables that need to be taken into consideration, which make it a difficult task,” he told FoxNews.com. “With unlimited time and money, they could pull it off and revolutionize space launch technology. But they only have so many launches, and each failure costs them money.”
SpaceX may try for an ocean landing again as early as June, when the next Dragon shipment is scheduled for launch.
(Excerpt) Read more at foxnews.com ...
Obviously I haven't put a lot of thought into this suggestion. :)
But they only have so many launches, and each failure costs them money.”
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I think they still make a pretty good profit. They are charging less than anyone else for that class of rocket. They do have to pay for the extra hardware on the rocket, the ship, and the manpower, but I doubt they are losing money on the launch. In the long run it is far more expensive to crash a very reusable rocket in the ocean.
I get why. I just don’t think its the way to go.
Its like trying to drop and nail and trying to have it stand on its head.
I wonder if Space X’s difficulties with landing on the barge might be due to any perceived motion of the target? That is, is there any movement, roll, pitch, and/or yaw in the drone ship that adversely affects how the rocket perceives the distance and attitude to the target?
It would be neat if they could do something like that. The rocket actually landed on the ship, but was at too much of an angle to stay upright.
I’m also reminded that Apollo 11’s Lunar Module had information overload errors and couldn’t keep up with the stream of information the landing radar was feeding it. Maybe something of the sort is happening with the Space X vehicle, too, and the guidance systems can’t stick the landing.
Looking at the good video of the landing, the ship does appear to rocking quite a bit, and it’s not that big of a target. As the rocket enters the top of the frame, the main engine, which is controlling lateral movement, is rocking back and forth (gimballing) quite a bit. (I’d say it was a having difficulty staying on target.) For the last few hundred feet there doesn’t seem to be any steering motion and the rocket begins to tilt quite a bit. As the rocket gets close to the deck, the engine gimbals again and steers back toward the center of the deck, but isn’t able to completely get the rockett back upright again.
The only part where they fail is the last 5 seconds.
Remember how early Satellite photos were physically caught, mid-air, by helicopters?
That’s what they’re going to do, and they’ll use a CH-47 or Osprey.
It will slow down 99%, deploy a huge hook or ring, and it will be caught, mid-air by the huge chopper or Osprey.
They’ll keep doing that until there is confidence in the last little bit, and that will be in a couple years.
Because why not? :)
They and.Boeing are getting huge subsidies
What I saw in the close up video was that is was coming in way too fast. I would estimate 30 feet per second within one booster length of the barge.
Then, the X/Y velocity was not zero and had to be corrected at the same time.
Too much, in too little time.
Musk needs to pull this off, having more fuel and burning it to zero the X/Y higher up and reduce the rate of descent higher up. Not by much. They know this, but don’t want to reduce payload.
Armchair engineer.
Instead of launching it east, how about to the north. That way they can set it down on land - probably near Washington D.C. And if it crashes ....
The vehicle will eventually land on its own.
The inverted pendulum problem is the very first one that every Controls engineer has to solve and landing Falcon is just that.
The recent attempt showed lack of control authority in the contingency case. That can and will be remedied.
Are there other ways to go for reusability? Millions. A lot have been tried (um, Shuttle) and walked away from. The mass capability loss to carry the fly back stuff (fuel for landing a stage, wings for fly back, chutes n’ stuff for capture/recover etc) usually is too big of a penalty to pay and then you have to overhaul the equipment to flight qualification levels.
Good luck with that. In the end, you find yourself spending about as much as if you just dumped it into the Atlantic.
How about four ships spaced 100’s of feet apart. With the ships having very round bottoms to allow for lots of roll (more like large buoys). Hang the net (carbon fiber?) up from masts to keep it up from the water.
Probably more expensive, but maybe less risk.
I think there is some similarity in that the Falcon stage is very unstable, not designed to land, and has limited ability to maneuver. The software probably has considerable constraints as to what it can do considering the above factors.
They want to avoid getting into a situation like what’s described here:
http://en.wikipedia.org/wiki/Pilot-induced_oscillation
I think what they are doing costs much less than the Shuttle, especially in the case of Spacex.
What they really should have done is landed it sideways so it won’t tip over. Duh....
Agreed.
That would be expensive, considering the ultimate goal is to return to land. Spacex is close. IMO, the last attempt was somewhat successful. The rocket did land on the ship, but with too much tilt to stay upright.
I think if they didn’t have to aim for such a relatively small target, they would be successful. In other words, if the could trade lateral accuracy for vertical stability, I think they can do it. They need to figure out the margin of error before the government will let them try, though. My guess would be a radius of less than 200 yards for the margin of error.
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