Some details on the SpaceX’s attempt to land its Falcon 9 first stage
This SpaceX press release gives some good info on the difficulty they face getting the first stage on Tuesday’s Dragon launch to land successfully on its floating sea platform:
To complicate matters further, the landing site is limited in size and not entirely stationary. The autonomous spaceport drone ship is 300 by 100 feet, with wings that extend its width to 170 feet. While that may sound huge at first, to a Falcon 9 first stage coming from space, it seems very small. The legspan of the Falcon 9 first stage is about 70 feet and while the ship is equipped with powerful thrusters to help it stay in place, it is not actually anchored, so finding the bullseye becomes particularly tricky. During previous attempts, we could only expect a landing accuracy of within 10km. For this attempt, we’re targeting a landing accuracy of within 10 meters.
They are going to try however, and they will be filming their attempt all the way. Stay tuned for some very interesting footage.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
This SpaceX press release gives some good info on the difficulty they face getting the first stage on Tuesday’s Dragon launch to land successfully on its floating sea platform:
To complicate matters further, the landing site is limited in size and not entirely stationary. The autonomous spaceport drone ship is 300 by 100 feet, with wings that extend its width to 170 feet. While that may sound huge at first, to a Falcon 9 first stage coming from space, it seems very small. The legspan of the Falcon 9 first stage is about 70 feet and while the ship is equipped with powerful thrusters to help it stay in place, it is not actually anchored, so finding the bullseye becomes particularly tricky. During previous attempts, we could only expect a landing accuracy of within 10km. For this attempt, we’re targeting a landing accuracy of within 10 meters.
They are going to try however, and they will be filming their attempt all the way. Stay tuned for some very interesting footage.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
If on this first attempt the F9 gets within a few hundred meters of the barge, I would consider that a success. To my knowledge the small steering wings added to guide the F9 down haven’t be used on such a flight. They’ve only been tested on the short grasshopper test flights which in no way simulates the full flight down from near orbital heights and velocities. I can’t imagine that some tweaking still remains to properly guide the F9 down to a 10 meter target in the middle of the ocean.
If a soft landing on the barge is indeed achieved on the first attempt, it will be a VERY impressive achievement. They have to have some rather spectacular simulation software for the guidance control algorithms to be coded against.
Can we assume the purpose of landing on a barge is safety for ground-dwellers, ease of returning the rocket to its spaceport, or both?
The barge is the next incremental step towards re-usability with considerations towards both safety for those on the land while demonstrating that 14 story object traveling at the speed of a rifle bullet can be guided down backwards with adequate precision. However, I believe the ultimate goal for the F9R is flyback of the first stage booster all the way to the launch site or somewhere else on dry land along the coast. The barge is just a stepping stone.
I agree with mpthompson, that the preferred method is to return directly to the launchsite/spaceport, but that requires extra fuel to turn around and then to stop the rocket’s “forward” motion again at the spaceport. However, the rocket would be immediately available for refurbishment, with no transportation-time delay spent on the barge.
The barge would still be available for launches in which the payload weight does not leave enough fuel in the first stage for it to return to the spaceport or in which the spaceport does not have a “landing pad.”
Landing on a rolling, rocking, pitching barge with who-knows-what kind of winds and gusts is quite a test of the system. Even after it lands on the barge, the rocket has to be prevented from tipping over – or blowing over – the side.
To paraphrase a song, if you can land it there, you can land it anywhere.
Good one.
Live coverage on their YouTube channel and the NASA feed is over at Spaceflight Now is starting as I type.
http://youtu.be/Ohnnl4nOcGU
http://spaceflightnow.com/2015/01/05/spacex-5-mission-status-center/
The steering panels are the same design as ones used on new free fall guided bombs and hypersonic missiles.
They are pretty good. They just needed to be scaled up to match the mass of the rocket.