
How Not to Land an Orbital Rocket Booster [video] - robin_reala
https://www.youtube.com/watch?v=bvim4rsNHkQ
======
iamrecursion
I have to appreciate the humour this shows. All in the name of progress, and
it certainly made me laugh.

SpaceX has somehow managed to turn landing a booster from space into something
almost mundane, but it bears remembering the failures that got them there.

~~~
froh42
You try and fail. And try and fail. And try and fail. And then one day you
have learned enough to try and succeed.

Learning how to NOT land it is learning how to land it.

~~~
jerf
As there is a definite Monty Python feeling to the video, I'd suggest this is
appropriate:
[https://youtu.be/aNaXdLWt17A?t=20s](https://youtu.be/aNaXdLWt17A?t=20s)

~~~
monk_e_boy
Did the Month Python music and quotes gave it away?

~~~
jerf
Congratulations on... noticing the same thing I did?

------
arethuza
I can't help thinking that the captions would make excellent Culture ship
names.

e.g.

ROU _Sticky Throttle Valve_

Edit: In case anyone is wondering about about the connection to the Culture,
the SpaceX "Autonomous spaceport drone ships" are named after Culture ships:

[https://en.wikipedia.org/wiki/Autonomous_spaceport_drone_shi...](https://en.wikipedia.org/wiki/Autonomous_spaceport_drone_ship)

 _Just Read the Instructions_

and

 _Of Course I Still Love You_

~~~
sohkamyung
Was there ever a ship called _It 's just a scratch_ ? That's sounds like a
good name too.

~~~
arethuza
Apparently not according to:

[https://en.wikipedia.org/wiki/List_of_spacecraft_in_the_Cult...](https://en.wikipedia.org/wiki/List_of_spacecraft_in_the_Culture_series)

Rather like 'Look, that's not an "Explosion"' as well... :-)

Edit: I'm hoping that the first manned ship on Mars will be "The Ends of
Invention".... ;-)

~~~
mschuster91
> Edit: I'm hoping that the first manned ship on Mars will be "The Ends of
> Invention".... ;-)

Problem with Mars landings is the high turnaround time - while you can see
what failed and fix it in a matter of days to weeks on Earth, with Mars you're
looking at months to years of having another attempt.

Wonder how they'll get it done - practice on Moon first?

~~~
JshWright
The Moon is not a super useful analog. It lacks any sort of atmosphere. Mars
has just enough atmosphere that you have to deal with it, but not enough of
one to be especially useful (parachutes buy you a little, but not much).

In fact, some of the best data and tests we have about landing big things on
Mars come from SpaceX's first stage booster landings. The burn that the first
stage does at the edge of space to slow down is in an environment very similar
to that of the Martian atmosphere.

[https://www.youtube.com/watch?v=_UFjK_CFKgA](https://www.youtube.com/watch?v=_UFjK_CFKgA)

~~~
simonh
The Moon isn't a useful analogy precisely because the Martian atmosphere does
make a significant difference. Just not enough to allow parachute-only soft
landings. I've seen the 'thick enough to be annoying, too thin to be useful'
meme before but it doesn't really match reality.

For example Pathfinder decelerated from 7.3km/s to 0.4km/s purely using it's
aeroshell, before it even deployed the parachutes[0]. Now 0.4km/s is still
pretty fast, but a saving of 6.9km/s dV is absolutely enormous.

Red Dragon was only possible because, with modifications to the capsule
aerodynamics, the Martian atmosphere would brake the capsule enough for it to
soft-land on the SuperDracos. There's no way a Dragon could usefuly soft-land
on the Moon. It's just way too heavy for it's size. All that thick capsule
hull is just dead weight for an airless environment. Given it's high dry mass
the rocket equation demands huge amounts of fuel to compensate. The parameters
are all wrong for the Moon because it's designed to use atmospheric drag to do
most of the work.

[0][https://en.wikipedia.org/wiki/Mars_atmospheric_entry](https://en.wikipedia.org/wiki/Mars_atmospheric_entry)

~~~
rtkwe
It's great and useful for smaller probes but as we've sent larger and larger
probes the thin Martian atmosphere has been less and less useful. One of the
major issues is that the mass keeps going up but the surface area of the heat
shields we can reasonably bring along doesn't scale as well. There's some
hopes in inflatable technologies though.

~~~
simonh
That is a good point. Red Dragon was only feasible by adding an asymmetric
sled under the capsule to provide lift, so it could spend significantly longer
braking through the atmosphere. Also the ITS video and presentation shows it
using it's lifting body design to maximise time up in the atmosphere. At that
scale straightforward aeroshells don't cut it, but you can still get a useful
effect.

------
dasmoth
Nice compilation, definitely some segments I don't remember seeing before.

With those out of the way though... they've attempted 10 landings so far this
year and all have been successful. Third flight of a reused booster is planned
for early next month.

...and fingers crossed for seeing all three cores from the Falcon Heavy test-
flight making successful landings.

~~~
JshWright
> definitely some segments I don't remember seeing before.

I'm bummed there isn't a better video of the March 2016 SES-9 failure (the
only shot in this video is the droneship on the horizon).

That was the landing that punched a hole in the deck of the droneship.

------
zbentley
My god, finally something that explodes as easily as all cars do in the
movies.

~~~
russellbeattie
I thought the same thing when that rocket slowly tipped over and still
completely self-destructed. I understand rocket fuel is volatile, but wow.

~~~
Narishma
Are we sure those are not intentionally/automatically triggered explosions?

~~~
Zaak
The grasshopper flight that flipped sideways then exploded was blown up by the
flight termination system. The rest of them are just pressurized tanks of
propellant rupturing in the presence of fire and/or red-hot metal.

------
dredmorbius
Landed orbital rocket boosters are all alike; every unlanded orbital rocket
boosters is unlanded in its own way.

------
robtaylor
"I didn't want to be the CEO of SpaceX, I wanted to be a Lumberjack." \- Elon
Musk

~~~
dsfyu404ed
Skidders and trucks in the mud vs rockets and barges. Same difference. The
toys he gets to play with are just different. Probably way less dick jokes,
facial hair and steel toe boots on a SpaceX job-site though.

~~~
JshWright
> Probably way less dick jokes, facial hair and steel toe boots on a SpaceX
> job-site though.

You don't think these folks are wearing safety tipped shoes and cracking dirty
jokes from time to time?

[https://www.gannett-
cdn.com/-mm-/caac49d6e3f44d10409a91a8bb8...](https://www.gannett-
cdn.com/-mm-/caac49d6e3f44d10409a91a8bb8b6a96db8e03f7/c=206-0-3060-2146&r=x1443&c=1920x1440/local/-/media/2016/05/10/Brevard/Brevard/635984826027372461-SpaceX-
at-Port-Canaveral-17.JPG)

~~~
dsfyu404ed
There's an direct relationship between ease of oversight and joke PCness.

Twenty dudes in the middle of nowhere turning trees into a piles of logs are
gonna be way more fun to hang around with than a team who's supervisor's
supervisor could easily drop by.

Follow some people who work odd hours on Snapchat/IG. Way more screwing around
happens on 3rd shift than 2nd or 1st.

IMO the morale boost of allowing people to screw around (relatively speaking)
during normal operations offsets the material decrease in productivity because
people are more willing to work hard in cases where you need maximum
productivity.

~~~
zaroth
On other threads about Uber and SoFi I think they call that a "frathouse
culture" which must be cleansed by fire.

~~~
dsfyu404ed
> I think they call that a "frathouse culture" which must be cleansed by fire.

The culture needed varies based on the nature of the work.

What works in an office doesn't necessarily work on a jobsite and vise versa.
Even then it varies by the nature of the job. The typical "condom full of
acetylene" would probably not go over well in a workplace that specializes in
something highly regulated.

------
agildehaus
Full video here:

[https://www.youtube.com/watch?v=bvim4rsNHkQ](https://www.youtube.com/watch?v=bvim4rsNHkQ)

------
ChuckMcM
It reminds me of the collection of failures film in the Redstone and Mercury
projects. That said, it also shows how closely managed the release of this
video was, after all when you just had a tweet from Elon and no pictures and
lots of questions, all you got were crickets.

I am glad they finally made it out, if only in partial form, for folks to see.
Landing _is_ hard, and there was a lot of things that didn't work. And it is
way more open than Blue Origin and their less successful flights.

------
smegel
They make it look so easy now.

In 20 years time we will be saying in amazement "you mean they used to just
throw away the boosters after each launch?".

Bravo spaceX.

~~~
DanHulton
I remember first hearing about it and thinking it was science fiction, unable
to really be achieved.

Glad to be wrong.

------
KON_Air
April 2015; this one looks good enough... then it explodes too.

~~~
JshWright
It had a _lot_ of lateral movement at touchdown. A "sticky" valve slowed the
engine's response to throttle commands. That led to a feedback loop as it got
further and further behind (you can see it gimbaling significantly back and
forth).

~~~
KON_Air
But it was almost slow enough to not explode.

~~~
JshWright
Once it tipped over, it was going to explode. You can see the cold gas
thruster at the top trying desperately to keep it upright, but it was just too
off-axis, and had too much lateral momentum.

------
jlebrech
Now I would like to see them attach 7 boosters together in a hexagonal pattern
and get them all to land safely.

~~~
LeifCarrotson
The Falcon Heavy is basically attaching 3 boosters together in a line.
Unfortunately for your vision, the Falcon Heavy boosters separate and land
one-by-one as individual boosters.

Your idea does make some intuitive sense. While lifting the single booster and
even with just one of 9 engines turned down to minimum throttle, when the
payload is gone and the tanks are near empty there's an enormous excess of
power. The minimum thrust-to-weight ratio is still like 2:1. This means you
have to run a "hoverslam" profile which reaches zero velocity precisely at the
deck, otherwise you'll take off again. And it means you come in terrifyingly
hot and fast, resulting in the explosions in the linked video.

With 7 boosters strapped together, you'd think there could be a more
appropriate ratio of power and mass, which would enable a more controlled,
sedate, hover-and-land profile. If the current 40% throttled down single-
engine, single-booster TWR is 2:1, 3 engines would give you a 0.86:1 to 2.14:1
TWR. They could even turn on 3 engines at the outer corners in an equilateral
triangle, and use both gimballing and differential thrust to control your
descent.

It should be easy. You'd just get some struts and select hexagonal
symmetry...oh wait, no, that's KSP. In reality, landing 7 boosters at once
with a near-unity TWR would be much more expensive in terms of fuel. You want
a hoverslam profile that's almost too fast to control, because then you can
get your payload higher and faster. Right now, with the single 9-engine
booster, they sometimes burn 3 of the 9 engines to land (giving a >6:1 power-
to-weight ratio). They do this when they're short on fuel because for every
second that they are airborne, they're suffering a 9.8 m/s hit to their
delta-V. They want to come down as fast as possible to minimize time in the
air.

~~~
jlebrech
my plan would be to separate the boosters too, you just need them stuck
together at launch.

or another plan would be to keep them together all the way to mars, and you
have a habitation unit above the boosters which is their combined surface
area.

when you launch the habitation unit you can later land another one next to it
the to tile them together.

------
lawlessone
They seem very fragile?

The one at 0:49 exploded just from tipping over.

Perhaps because they're huge i guess.

~~~
bryananderson
Every pound of weight you add to the rocket is a pound of payload that you
can't put into space.

~~~
JshWright
It's not technically 1:1 on the first stage. It varies a bit from launcher to
launcher, but it's in the ballpark of 4:1 (you lose a pound of useful payload
for every four pounds you add to the first stage).

Your point is spot on though. Don't waste mass to account for failure modes
that you can just avoid in the first place by landing upright.

------
robin_reala
There’s now a high res version at
[https://www.youtube.com/watch?v=bvim4rsNHkQ](https://www.youtube.com/watch?v=bvim4rsNHkQ)
. Could a mod update the URL for this story?

------
fotcorn
Direct link to video for fullscreen view:

[https://scontent-
frx5-1.cdninstagram.com/t50.2886-16/2173252...](https://scontent-
frx5-1.cdninstagram.com/t50.2886-16/21732525_713249985525933_1412086930828427264_n.mp4)

~~~
lorenzhs
that's only the first minute. robin_reala has a full-length youtube version
that's also high definition.

