
Falcon 9 first stage found, but probably not recoverable - cryptoz
http://www.spaceflightinsider.com/space-flight-missions/commercial-space-space-flight-missions/spacex/crs-3/spacex-president-shotwell-talks-recovery-efforts-recent-ribbon-cutting-ceremony/
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Arjuna
The article reports that the first stage achieved a near zero velocity
landing. Another critical marker that was achieved, which is closely related,
is that the first stage's flight dynamics (i.e., pitch, roll and yaw) were
correct. Previously, the first stage was destroyed because the flight dynamics
were incorrect. Also, the first stage continued to report telemetry for 8
seconds after the water landing.

Does anyone know if the first stage's landing legs were successfully deployed
before the water landing? These are the 4 carbon fiber and aluminum legs (each
25ft / 7.6m long) that would be used to land the stage. I know that Falcon 9
launched with them, but I don't know if they were deployed. My suspicion is
that they would have attempted to deploy them as well, for verification and
validation purposes.

~~~
Patrick_Devine
SpaceX hasn't confirmed it, however I would assume that that would be the
case. Elon has stated in the past that the legs would provide pitch stability
which was missing in the last attempt to relight the first stage. Without it
the first stage likely would tumble and a relight would be impossible due to
the propellant being centrifuged.

Here's a link which talks about it (about halfway through the article):
[http://www.space.com/23009-spacex-falcon-9-rocket-launch-
tes...](http://www.space.com/23009-spacex-falcon-9-rocket-launch-test-first-
person.html?utm_source=twitterfeed&utm_medium=facebook&utm_campaign=Feed%3A+AutoSpaceNews+%28Automated+Space+News%29)

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XorNot
Damn. Here's hoping they feel confident enough about their guidance to try a
land touchdown next time.

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msandford
If it were me I'd probably try and get an old oil rig that's headed for the
scrap yard and put a large, uniform platform on it and try and land on that.
If something goes terribly wrong it will happen 20 miles from anything. The
majority of rigs don't bob, they either sit on the ocean floor or they're
tethered down so the up and down motion that would happen when they're free is
actually translated into more or less tension in the anchor cables.

I was thinking "barge" at first but if the seas were rough it'd get tossed
about and make landing a disaster.

EDIT: It would probably cost millions for all the steel even at salvage value,
but that's probably a lot cheaper than the insurance (if you can even buy it)
for having a reusable rocket come back over land and attempt a landing,
however remote the location.

~~~
Justsignedup
We still have the primary problem: If it hits a town (due to any error, such
as an unforeseen destruction of a component) the human casualty would be a
disaster. It's not even just the $$.

A barge would not work because it is mobile as well.

This is indeed rocket science.

~~~
extropy
That's why they have range safety.
[http://en.m.wikipedia.org/wiki/Range_safety](http://en.m.wikipedia.org/wiki/Range_safety).
Basically a remote self-destruct trigger with multiple redundant data channels
and possibly a self destruct on communication loss. You will get some debris
but the damage is lot more predictable than a full stage coming down.

~~~
001sky
Isn't the issue that 'range safety' isn't really a landing feature? Look at
the shuttle strewn out over texas. Range safety is fine for launch (when you
have control over initial trajectory and location); or for a test-flight that
is retsricted to and actual missle range (or other restricted airspace).

~~~
Crito
I am not sure what you mean. The Space Shuttle Orbiter did not have range
safety. Range safety played no role in the Columbia disaster.

~~~
001sky
The space shuttle has range safety, but only during launch. The shuttle
launches over the ocean, which allows for 'range safety' to be implemented, on
the SRBs and EFT.

Since the shuttle's re-entry flightpath is not constrained to restricted
airspace, destroying the shuttle orbiter deliberately would only be "range
safety" in the loosest sense.

Empirical data seem to suggest Columbia began to self-destruct over the CA/AZ
border before landing in a debris field scattered over (populated) west Texas.
As seen from an actual destructive episode, the debris path/cone was
extensive, and unlikely to be constrained to air-space designated for such
purposes.

The issues about how to mitigate this problem comes down to some of the things
noted in at least one other comment here--basically SpaceX would limit the re-
entry flight-path to open-ocean during approach.

Even then, the question is about ballistic "backstop"/shadow of its landing
site ("the beach").

These are pretty basic questions about the size and nature of the landing
facility and the ballistic match of un-guided (and potentially un-aerodynamic)
debris based upon whatever the realistic assumptions of velocity/altitude and
response time of the system are.

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Crito
The SRBs and external fuel tanks had range safety, but as I said, the Shuttle
_Orbiter_ did not. Any "self-destructing" that Columbia did was due to extreme
forces induced by the atmosphere.

The willingness to fly a manned reentering Shuttle Orbiter over populated land
without range safety should not be misconstrued as the willingness to drop an
unmanned first stage down with engine power without range safety.

They use range safety for launches at those same locations with planned flight
paths over the same ocean. I see little reason for them to _not_ use range
safety for landings.

~~~
001sky
The orbiter (re-entry vehicle) is well know to lack range safety, unlike the
full space shuttle (launch system). That is clear from my earlier comments.
That is not a point on which anyone is dis-agreeing.

With that out of the way, lets look at the issue at hand.

Two issues comprise range-safety and both are at play: (1) is the egineering;
and (2) is the flight paths. Proper range safety requires both (1) and (2)
combined. The orbiter-as-re-entry vehicle lacked both (1) and (2). Whist the
shuttle launch system had them both.

Certainly space X could engineer (1) and (2) using similar techniques at
launch with no issue.

The open question is simply providing for range safety for the re-
entry/recovery portion of the flight. The shuttle providese little to no road-
map in that regards.

Just the opposite: it illustrates some of the difficulties.[0]

Assuming an engineered solution is present (ie, pt1 above) what would the
limitations on the flight-patch (ie, pt 2 above) need to be in order that the
comination (1,2) together would qualify as "range safety" in the legitimate
sense.[1]

The ~rough~ answer seems to be (2') needs to be kept over water/open ocean.

So, my question is more about ballistics math: what is the envelope of
precision needed to keep something either (a) in the ocean; and/or (b) out of
harms way if the event is triggered closer to land.

The answer to that is something the engineers at SpaceX have surely
considered.

I don't know what those calculations show; it (surely) can be safely done up
to some threshold.

The question then simply is "what is the threshold"?

_____________________

[0] The scale of the debris cone from a columbia's ("natually occurring")
event @ 100,000+ ft is illustrative of a couple things. None of: China Lake,
White Sands, and Barry Goldwater etc alone could ~readily contain such an
event. We know this because all were proximate to the debbris path (ie,
western CA, Southern AZ, South/Central NM).

[1] see, eg s.6.2.1 (ff) of this report>
[http://sites.wff.nasa.gov/multimedia/docs/RangeSafetyManual....](http://sites.wff.nasa.gov/multimedia/docs/RangeSafetyManual.pdf)

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RALaBarge
The fact that SpaceX has come so far in such a short time is amazing. I am
quite confident that they will overcome any technical challenges RE: re-usable
first stages

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outworlder
That's to be expected. But they got some very valuable data out of it.

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cmapes
Quick correction to the article: Gwynne Shotwell is not the President & CEO,
she is the President & COO. It's very well known that Elon Musk is the CEO.

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astrowilliam
This is an absolutely incredible feat of engineering and science. GO SPACEX!

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nealabq
For launches over land, how about landing in a lake instead of the ocean? It'd
be easier to find, and salt water is corrosive.

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jessriedel
If you're confident enough that you can safely bring the rocket back over land
to a target location like a lake, you might as well land it on the ground. The
reason these stages land in the ocean is because it's a big safe place to drop
a piece of metal you don't have control of.

