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  [Discuss] SpaceX CRS-6 space station mission

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Author Topic:   [Discuss] SpaceX CRS-6 space station mission
Robert Pearlman
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posted 04-01-2015 07:59 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Please use this topic to discuss the sixth of SpaceX's contracted Dragon cargo flights to the International Space Station under NASA's Commercial Resupply Services (CRS) Program.

topmiler
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From: eastleigh, hampshire, UK
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posted 04-01-2015 07:59 AM     Click Here to See the Profile for topmiler     Edit/Delete Message   Reply w/Quote
Anyone know why it's been delayed till April 13th?

Robert Pearlman
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posted 04-01-2015 08:00 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Per Spaceflight Now and SpaceNews, neither SpaceX nor NASA has offered an explanation for the delay.
The Falcon 9 rocket’s liftoff from Cape Canaveral was due for no earlier than April 10, but the launch date has been delayed to April 13. Officials did not provide a reason for the delay.

cycleroadie
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posted 04-02-2015 04:03 AM     Click Here to See the Profile for cycleroadie   Click Here to Email cycleroadie     Edit/Delete Message   Reply w/Quote
The Kennedy Space Center Visitor Complex has sent out notices that it's moved to April 13 at 4:33 p.m. NASA's website is showing the same.

Robert Pearlman
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posted 04-08-2015 03:32 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
SpaceX photo release
Falcon 9 First Stage Reusability Graphic

Wondering how Falcon 9's first stage will attempt to fly back to Earth on our next launch? The next attempt to land will take place during the launch of Cargo Dragon's CRS-6 mission to the International Space Station, currently slated for April 13.

Robert Pearlman
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posted 04-11-2015 08:19 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA update:
Meteorologists predict a 60 percent chance of acceptable conditions Monday (April 13) for the launch of the CRS-6 mission on a SpaceX Falcon 9 rocket and the Dragon spacecraft carrying experiments, equipment and supplies to the International Space Station where astronauts will use the materials to continue their cutting edge research off the Earth, for the Earth.

Liftoff is scheduled for 4:33 p.m. EDT (2033 GMT) Monday from Cape Canaveral Air Force Station.

Solarplexus
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posted 04-13-2015 03:21 PM     Click Here to See the Profile for Solarplexus     Edit/Delete Message   Reply w/Quote
Live at: Livestream.

Robert Pearlman
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posted 04-13-2015 03:32 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Weather violations have scrubbed today's launch attempt. Next attempt on Tuesday (April 14) at 4:10 p.m. EDT (2010 GMT).

Cozmosis22
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posted 04-14-2015 11:46 AM     Click Here to See the Profile for Cozmosis22     Edit/Delete Message   Reply w/Quote
Today's launch is still a GO with a 60% chance (same as yesterday) of acceptable weather conditions.

Robert Pearlman
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posted 04-14-2015 03:31 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
From Elon Musk on Twitter:
Ascent successful. Dragon enroute to Space Station. Rocket landed on droneship, but too hard for survival.

bunnkwio
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posted 04-14-2015 03:41 PM     Click Here to See the Profile for bunnkwio   Click Here to Email bunnkwio     Edit/Delete Message   Reply w/Quote
I was able to see the launch while sitting here at an airport, but was more excited to hopefully see the rocket landing.

It'll be quite amazing to watch when it eventually successfully happens!!!

Robert Pearlman
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posted 04-14-2015 03:59 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
From SpaceX on Twitter:
Falcon 9 first stage approaches Just Read the Instructions.

Robert Pearlman
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posted 04-14-2015 04:05 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
And from Elon Musk on Twitter:
Looks like Falcon landed fine, but excess lateral velocity caused it to tip over post landing.

All we have right now is low frame rate video (basically pictures). Normal video will be posted when ship returns to port in a few days.

Robert Pearlman
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posted 04-14-2015 08:55 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
SpaceX video:
Falcon 9 first stage landing burn and touchdown on Just Read the Instructions

Robert Pearlman
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posted 04-14-2015 10:48 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Elon Musk in a tweet to John Carmack:
Looks like the issue was stiction in the biprop throttle valve, resulting in control system phase lag. Should be easy to fix.

SpaceAngel
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posted 04-15-2015 09:30 AM     Click Here to See the Profile for SpaceAngel   Click Here to Email SpaceAngel     Edit/Delete Message   Reply w/Quote
Why can't SpaceX get it right?!

Robert Pearlman
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posted 04-15-2015 09:49 AM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Landing a rocket on a boat is hard. This was only their second attempt. I think giving them some slack is appropriate.

GACspaceguy
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posted 04-15-2015 10:33 AM     Click Here to See the Profile for GACspaceguy   Click Here to Email GACspaceguy     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by SpaceAngel:
Why can't SpaceX get it right?!

In aviation we call these development flights. While we do not fail the vehicle in this case it is a 1 or 0 for success. Looks to me they are zeroing in on the right configs and software for sucess.

I must say they have a great go forward positive attitude.

Robert Pearlman
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posted 04-15-2015 08:16 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
SpaceX video release
CRS-6 First Stage Landing

SkyMan1958
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posted 04-15-2015 08:50 PM     Click Here to See the Profile for SkyMan1958   Click Here to Email SkyMan1958     Edit/Delete Message   Reply w/Quote
Wow, that was coming down faster than I expected.

I think it's GREAT that SpaceX is taking the time and effort to learn how to land and recycle the first stage of their Falcon.

spaced out
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posted 04-16-2015 07:40 AM     Click Here to See the Profile for spaced out   Click Here to Email spaced out     Edit/Delete Message   Reply w/Quote
It's amazing to watch a rocket attempt to land in this way and on this second attempt it comes very close to succeeding. It's clear that they're going to get it perfected soon.

Hats off to SpaceX for attempting something that's both totally novel and extremely challenging.

jasonelam
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posted 04-16-2015 09:16 AM     Click Here to See the Profile for jasonelam   Click Here to Email jasonelam     Edit/Delete Message   Reply w/Quote
They almost stuck the landing. Looked like the lateral motion at the end caused it to fall over.

I have to admit when they first announced they were going to try this, I was skeptical. First try came very close and this time even closer. Remember it took SpaceX four tries to get to orbit with the Falcon 1.

Robert Pearlman
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posted 04-16-2015 02:16 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Another video the landing, this time from the deck of the drone ship:

dabolton
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posted 04-16-2015 02:35 PM     Click Here to See the Profile for dabolton     Edit/Delete Message   Reply w/Quote
Watching this brings up a technical question. What exactly causes a rocket to explode if it tips over? Is it the tanks rupturing or is it uncontrolled fuel being released into the engines?

If its the tanks failing, wouldn't that be a solvable engineering problem to create a tank that survives a zero-altitude/zero-velocity tip-over?

Uncontrolled fuel flow should be stopped by closing any open valves if it starts to tip.

Robert Pearlman
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posted 04-16-2015 03:26 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
With regards to engineering tip-proof tanks (whether that was the issue here or not), one would assume any such solution would add weight. Since the ascent is paramount to the entire effort, the focus is probably more on preventing tip over than protecting against it.

As for closing the valves, the stage seems to be attempting to right itself until the last second. I don't know if you would want to curtail that effort, or when you would, given the multitude of scenarios that could trigger such a reaction.

ejectr
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posted 04-16-2015 05:05 PM     Click Here to See the Profile for ejectr   Click Here to Email ejectr     Edit/Delete Message   Reply w/Quote
Almost..! They're getting there and they'll do it.

It's coming down fast because it has limited fuel. Maybe now that they know the fuel level, they'll slow it down a tad.

music_space
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posted 04-17-2015 02:17 PM     Click Here to See the Profile for music_space   Click Here to Email music_space     Edit/Delete Message   Reply w/Quote
It is a challenging feat of engineering to land an object with a high center of gravity in such a manner.

Remember that before the lunar orbit rendezvous was selected for Apollo, a similar method was envision for landing on the Moon. Albeit it was to be piloted rather than automated, it retrospectively seems to me as a hurdle that had limited probability to be mastered...

Robert Pearlman
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posted 04-17-2015 04:55 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
A Jacksonville-based Reddit user (Owt_On_A_Limb) has snapped a photo of the drone ship after its return to port:

ilovespace
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posted 04-17-2015 05:07 PM           Edit/Delete Message   Reply w/Quote
Wow, I was expecting much more damage than that.

Robert Pearlman
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posted 04-17-2015 05:20 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Musk said on Twitter that it was more a fast fire than an explosion.

Robert Pearlman
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posted 04-18-2015 10:27 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
Elon Musk on Twitter:
Cause of hard rocket landing confirmed as due to slower than expected throttle valve response. Next attempt in 2 months.

Blackarrow
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posted 04-20-2015 04:54 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
If they get this to work, and if you were an astronaut due to travel to the ISS on a "Dragon" launch, would you prefer to fly on a brand-new Falcon 9 launcher, or one that had been flown before and recovered? Do they reuse the 9 Merlin engines? Would you have more confidence in a rocket which had already flown successfully? I can't help thinking of the times I've been on an airliner which has made a safe but very heavy landing. I usually think: "I'm glad I'm not going to be on the next flight!"

Robert Pearlman
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posted 04-20-2015 05:08 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
SpaceX test fires all of its Merlin engines in Texas before they are used for a launch out of Florida or California, and so the engines are, at least in some regard, being reused when they lift off the pad.

(The engines are also tested again on the pad for a shorter duration static fire a few days before launch.)

GACspaceguy
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posted 04-20-2015 08:50 PM     Click Here to See the Profile for GACspaceguy   Click Here to Email GACspaceguy     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Blackarrow:
I can't help thinking of the times I've been on an airliner which has made a safe but very heavy landing. I usually think: "I'm glad I'm not going to be on the next flight!"
Modern aircraft have on board g-meters to determine if there has been a landing hard enough to do a hard landing inspection before the next flight. That hard landing inspection will find any issues that need addressing due to the event. Same with SpaceX, they will have data and checks that allow return to service.

Paul78zephyr
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posted 04-25-2015 09:23 AM     Click Here to See the Profile for Paul78zephyr     Edit/Delete Message   Reply w/Quote
I love the idea of reusability but wouldn't a parachute or retro rocket setup with a giant net of some type be simpler than trying to drop a pencil from 100 miles and having it land straight up on its eraser?

Jim Behling
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posted 04-25-2015 11:01 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
Define the "giant net" and how it is going to not damage the vehicle and how is the vehicle suppose to be guided towards the net?

Robert Pearlman
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posted 06-25-2015 01:43 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
SpaceX has released more details about its attempt to recover the CRS-6 first stage:
Our second attempt was in April, and we were super close to sticking this landing. Check out this previously unreleased, longer video from our tracking camera. It shows the stage’s descent through the atmosphere, when the vehicle is traveling faster than the speed of sound, all the way to touchdown.

That controlled descent was spectacular, but about 10 seconds before landing, a valve controlling the rocket’s engine power (thrust) temporarily stopped responding to commands as quickly as it should have. As a result, it throttled down a few seconds later than commanded, and—with the rocket weighing about 67,000 lbs and traveling nearly 200 mph at this point—a few seconds can be a very long time. With the throttle essentially stuck on “high” and the engine firing longer than it was supposed to, the vehicle temporarily lost control and was unable to recover in time for landing, eventually tipping over.

Last-second tilt aside, the landing attempt happened pretty much exactly as planned. Shortly after stage separation (when the second stage leaves the first stage behind and goes on to carry Dragon to orbit), cold gas thrusters fired to flip the stage to reorient it for reentry. Then, three engines lit for a “boostback burn” that slows the rocket and brings it toward the landing site.

The engines then re-lit to slow the stage for reentry through Earth’s atmosphere, and grid fins (this time with much more hydraulic fluid) extended to steer the lift produced by the stage. Our atmosphere is like molasses to an object traveling at Mach 4, and the grid fins are essential for landing with precision. The final landing burn ignited, and together the grid fins, cold gas thrusters and steerable engines controlled the vehicle, keeping the stage within 15 meters of its target trajectory throughout the landing burn. The vehicle’s legs deployed just before it reached our drone ship, “Just Read the Instructions”, where the stage landed within 10 meters of the target, albeit a bit too hard to stay upright.

Post-launch analysis has confirmed the throttle valve as the sole cause of this hard landing. The team has made changes to help prevent, and be able to rapidly recover from, similar issues for the next attempt, which will be on our next launch—the eighth Falcon 9 and Dragon cargo mission to the space station, currently scheduled for this Sunday.

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