What "weed need" is a space mission!

[Fred]

This...

[kladner]

LOL @ taco cat

[only_human]

Originally Posted by Dubslow

I have a funny image in my head of Elon Musk losing a drinking game with old man Murphy

Or being trapped in a maliciously purgatorial Harlan Ellisonesque nightmare.

Watch SpaceX's Fifth Attempt to Launch Its Falcon 9 Rocket Live, Which Will Make You Question the Very Nature of Reality

For the fifth time in just over a week, SpaceX is trying to launch its Falcon 9 Rocket. Am I stuck in a timeloop? Is any of this real? Am I here? Are you?

SpaceX attributed the first four scrubbed launches to problems with their liquid oxygen system, heavy winds, and a boat straying too close to the launch zone. Alternately, we both died thousands of years ago and in this—our purgatory—we relive the same day over and over again. Having long ago been forgotten by an indifferent God above, we remain trapped here together forever in our time prison doomed to repeat, but never able to change, our interminable present.

A good breakdown of this particular launch's various stage objectives:
http://spaceflight101.com/falcon-9-s...off-on-friday/

[only_human]

Here's a description a "boost-back burn":
http://spaceflight101.com/spacerockets/falcon-9-ft/

Around T+4.5 minutes into the mission, the first stage re-lights a subset of its engines for a boost-back maneuver that slows the vehicle down (or reverses its travel direction) and controls the downrange travel distance of the stage, beginning to target the planned landing site – either on land or in the ocean. The duration of the boost-back burn depends on the target landing site and is also driven by propellant availability for the return which varies depending on payload mass and insertion orbit.

Heading back into the dense layers of the atmosphere, the first stage completes its supersonic retro propulsion burn using three engines that are fired for about 20 seconds starting at an altitude of 70 Kilometers. This burn in combination with drag in the atmosphere slows the first stage down from 1,300m/s to about 250m/s.

It sounds as though they are saying this maneuver will be completely omitted in today's flight based on this:
http://spaceflight101.com/falcon-9-s...off-on-friday/

Instead of conducting a boost-back maneuver, the first stage will remain on a ballistic trajectory and home in on the Autonomous Spaceport Drone Ship, stationed 660 Kilometers from Cape Canaveral. Because the first stage can not slow down ahead of re-entry, it will have to endure extreme forces and temperatures not seen in previous attempts including the successful booster landing in December.

As for chilling fuel, the first link above says:

NASA studies have shown that LOX densification can increase the oxidizer mass by 8 to 15% compared to boiling-point LOX at –183°C.

Cooling LOX below its boiling point is possible through the use of a Nitrogen subcooler that employs a Liquid Nitrogen bath (either at boiling point or sub-cooled) through which the LOX lines are running to allow an exchange of heat.

SpaceX employs LOX at a temperature of approximately –207°C, about 10°C above the Oxygen Triple Point achieved by running the LOX through a Nitrogen bath that is kept at a partial vacuum to decrease its temperature to nearly N2 ice temperature. This will yield an increase in LOX density from 1.134 grams per cubic centimeter to nearly 1.23g/cm³ while still maintaining the LOX above its freezing point and slush density of 1.338g/cm³. Cooling the LOX to this temperature point yields a density increase of around 8%.

Operational launchers that employ sub-cooled LOX are Antares (in its original version, using LOX at –196°C) and Soyuz 2-1v (-192°C LOX), but in these cases, sub-cooled LOX is/was required due to the design of the engine.

Cooling the fuel, Rocket Propellant 1 (Kerosene), is also possible, although its high freezing temperature of approximately –37°C and changes in viscosity as a function of temperature represent limitations when cooling the fuel. SpaceX chills the RP-1 from ambient temperature down to approximately -7°C where viscosity does not yet affect the properties of the fuel, but achieves an increase in density around 2.5 to 4%.

Because of the different densification possible for LOX and RP1, an adjustment of tank sizes on the rocket is necessary to keep the Oxidizer to Fuel ratio required by the Merlin 1D engines.

This is accomplished by shortening the LOX tank on the first stage and stretching the RP-1 tank while retaining the original first stage length. Stretching the first stage beyond the length of the v1.1 first stage is not possible due to bending forces occurring in flight. Widening the diameter of the stages is also no option because of the requirement of road transport, putting a limit on the maximum diameter. The second stage of Falcon 9 FT accommodates the required change in RP-1 volume by stretching the stage.

[only_human]

Streaming now

SpaceX
We’re targeting today, Friday, March 4 at 6:35pm ET for launch of SES-9. The window extends to 8:06pm ET. The SpaceX webcast is scheduled to go live here (on http://www.spacex.com/webcast) and on YouTube about 10 minutes prior to launch. For rocket views, launch countdown audio and telemetry info, use this link for our technical webcast: https://www.youtube.com/watch?v=sIkPP2LM8DU

Full
http://youtu.be/muDPSyO7-A0

Technical
http://youtu.be/sIkPP2LM8DU

Progress updates on twitter:
https://mobile.twitter.com/S101_Live
reddit
https://www.reddit.com/r/spacex/comm...ssion_updates/

Approximate countdown timeline via spaceflight101.com
http://spaceflight101.com/falcon-9-f...down-timeline/

[chalsall]

Originally Posted by only_human

Streaming begins in 26 minutes.

Stream just went live!

[Dubslow]

Launch!

That Stage 1 recovery looked pretty... kinematic, if you catch my drift.

[only_human]

Originally Posted by Dubslow

Launch!

That Stage 1 recovery looked pretty... kinematic, if you catch my drift.

These video cutouts suck. Someone on reddet quipped "Schrödinger's rocket."

Elon Musk ‏@elonmusk
Target altitude of 40,600 km achieved. Thanks @SES_Satellites for riding on Falcon 9! Looking forward to future missions.

Elon Musk – Verified account ‏@elonmusk

Rocket landed hard on the droneship. Didn't expect this one to work (v hot reentry), but next flight has a good chance.

[Dubslow]

AFAICT there is no video released of the booster landing with better visuals than we saw during the webcast?

[Uncwilly]

Originally Posted by Dubslow

AFAICT there is no video released of the booster landing with better visuals than we saw during the webcast?

There should be. As hinted at in the broadcast, when the booster comes in for a landing, it shakes the drone ship and the drone ship loses satellite lock. This interrupts the feed. But then later, the data can be recovered from on-board sources.

[only_human]

Originally Posted by Uncwilly

There should be. As hinted at in the broadcast, when the booster comes in for a landing, it shakes the drone ship and the drone ship loses satellite lock. This interrupts the feed. But then later, the data can be recovered from on-board sources.

Found this clip out there. Dunno where it came from or anything else about it.
https://m.youtube.com/watch?v=aARSV1GT1Ic