
SpaceX loses the center core of its Falcon Heavy rocket due to choppy seas - malshe
https://www.theverge.com/2019/4/15/18311945/spacex-falcon-heavy-center-core-drone-ship-rough-ocean
======
hsnewman
I can't believe they didn't tie them down.

~~~
zackbloom
It explains in the article. The waves were too high to get crew on the
droneship to tie it down, and they only got worse.

~~~
stcredzero
Developing a robot which can tie down the rocket in very heavy seas would be
very, very hard. (A "walker" which has grasping feet?) Not only is the
coordination and basic locomotion difficult in very heavy seas, just dealing
with salt water is hard in itself.

~~~
burfog
Nah. There are multiple options:

View the problem of reaching the rocket as similar to locating the head of a
CNC or 3D printer. You need XY positioning. Put the gripper on a bridge that
spans the ship. The gripper moves along that bridge for movement in one
direction. The bridge itself moves along tracks in the sides of the ship,
providing the other dimension of movement. The mechanism can be doubled up to
grab from both sides simultaneously, possibly eliminating the need for an
active gripper.

Another way is an arm. An ordinary heavy-equipment arm, as used for digging up
roads, could reach out and pin down a leg of the rocket. It need not be
automatic; a human could remotely operate it. The vertical dimension isn't
really needed, so sliding the arm is also an option.

Another way is to flood the deck with adhesive, possibly something like molten
solder or polyurethane foam.

Another way is to pre-place grippers all over the deck. Make a deck of
grippers. They just grip; they do not need to move around on the deck. It can
be mechanical, electromagnetic, or vacuum.

~~~
stcredzero
_Nah. There are multiple options:_

None of which are trivial in terms of expense or engineering.

 _View the problem of reaching the rocket as similar to locating the head of a
CNC or 3D printer. You need XY positioning._

To reach all the legs, you'd need two. As these are the dimension of the
entire landing pad, they'd cost more. They're essentially gantries. Also,
they'd still need to be engineered to withstand and remain operational in
heavy seas. Would they be running on hydraulics? What of the effects of the
rocket blast. What happens if there is a hydraulic oil leak?

 _Another way is an arm. An ordinary heavy-equipment arm, as used for digging
up roads, could reach out and pin down a leg of the rocket._

Those would certainly be hydraulic, so the same objections above apply. This
is a good use of existing commodity equipment -- except that it would have to
be hardened against the sea and the rocket blast as well, so it would still be
an expensive specialty item.

 _It need not be automatic; a human could remotely operate it._

Keeping telemetry going while the rocket is landing is still something they
haven't solved.

 _Another way is to flood the deck with adhesive, possibly something like
molten solder or polyurethane foam._

It's thinking outside the box, but this isn't going to work 100% in heavy
seas. I suspect that any adhesive that would work in heavy seas in the
necessary time frames would be expensive to remove afterwards.

 _Another way is to pre-place grippers all over the deck. Make a deck of
grippers._

How about make the deck out of slotted rails? Make gripper robots which are
designed to move on these rails or between rails? Also the slotted rail system
can be made into a 2D grid.

~~~
burfog
You don't need to reach all the legs, although that is best. Grabbing the body
is also an option; the launch crawler/pad thing does this. That first example
would probably not be hydraulic. If it were though, and it leaked, that isn't
any worse than the total-loss (intentional leak) hydraulic system that
operates the grid fins on the Falcon 9.

The rocket blast isn't anything special for heavy equipment that is some
distance away. Note the containers sitting on the ship. They are fine.

Grabbing can happen a minute after the engines stop, so telemetry isn't a
problem.

------
hinkley
I wonder if stabilization tech is worth their time and trouble.

~~~
stcredzero
Didn't crew just weld the booster feet to the deck after earlier landings?

~~~
majormjr
That's a pretty common method of attaching large metal objects with cargo
ships too. Fast and a very strong connection.

------
F_r_k
Where's the Roomba when they needed it ?

