Topic: [Discuss] SpaceX CRS-6 space station mission
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-01-2015 07:59 AM
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 Member
Posts: 148 From: eastleigh, hampshire, UK Registered: Jul 2012
posted 04-01-2015 07:59 AM
Anyone know why it's been delayed till April 13th?
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-01-2015 08:00 AM
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 Member
Posts: 452 From: Apalachin, NY USA Registered: May 2011
posted 04-02-2015 04:03 AM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-08-2015 03:32 PM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-11-2015 08:19 PM
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.
posted 04-14-2015 11:46 AM
Today's launch is still a GO with a 60% chance (same as yesterday) of acceptable weather conditions.
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-14-2015 03:31 PM
From Elon Musk on Twitter:
Ascent successful. Dragon enroute to Space Station. Rocket landed on droneship, but too hard for survival.
bunnkwio Member
Posts: 113 From: Naperville, IL USA Registered: Jul 2008
posted 04-14-2015 03:41 PM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-14-2015 03:59 PM
From SpaceX on Twitter:
Falcon 9 first stage approaches Just Read the Instructions.
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-14-2015 04:05 PM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-14-2015 08:55 PM
SpaceX video:
Falcon 9 first stage landing burn and touchdown on Just Read the Instructions
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-14-2015 10:48 PM
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 Member
Posts: 307 From: Maryland Registered: May 2010
posted 04-15-2015 09:30 AM
Why can't SpaceX get it right?!
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-15-2015 09:49 AM
Landing a rocket on a boat is hard. This was only their second attempt. I think giving them some slack is appropriate.
GACspaceguy Member
Posts: 2476 From: Guyton, GA Registered: Jan 2006
posted 04-15-2015 10:33 AM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-15-2015 08:16 PM
SpaceX video release
CRS-6 First Stage Landing
SkyMan1958 Member
Posts: 867 From: CA. Registered: Jan 2011
posted 04-15-2015 08:50 PM
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 Member
Posts: 3110 From: Paris, France Registered: Aug 2003
posted 04-16-2015 07:40 AM
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 Member
Posts: 691 From: Monticello, KY USA Registered: Mar 2007
posted 04-16-2015 09:16 AM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-16-2015 02:16 PM
Another video the landing, this time from the deck of the drone ship:
dabolton Member
Posts: 419 From: Seneca, IL, US Registered: Jan 2009
posted 04-16-2015 02:35 PM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-16-2015 03:26 PM
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 Member
Posts: 1751 From: Killingly, CT Registered: Mar 2002
posted 04-16-2015 05:05 PM
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 Member
Posts: 1179 From: Canada Registered: Jul 2001
posted 04-17-2015 02:17 PM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-17-2015 04:55 PM
A Jacksonville-based Reddit user (Owt_On_A_Limb) has snapped a photo of the drone ship after its return to port:
ilovespace unregistered
posted 04-17-2015 05:07 PM
Wow, I was expecting much more damage than that.
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-17-2015 05:20 PM
Musk said on Twitter that it was more a fast fire than an explosion.
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-18-2015 10:27 PM
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 Member
Posts: 3120 From: Belfast, United Kingdom Registered: Feb 2002
posted 04-20-2015 04:54 PM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 04-20-2015 05:08 PM
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 Member
Posts: 2476 From: Guyton, GA Registered: Jan 2006
posted 04-20-2015 08:50 PM
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 Member
Posts: 675 From: Hudson, MA Registered: Jul 2005
posted 04-25-2015 09:23 AM
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 Member
Posts: 1463 From: Cape Canaveral, FL Registered: Mar 2010
posted 04-25-2015 11:01 AM
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 Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 06-25-2015 01:43 PM
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.
posted 04-01-2015 07:59 AM
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