from the better-to-delay-than-explode dept.
According to SpaceFlight Now, SpaceX's SES-9 launch was again aborted in the final minutes. That launch was, in itself, originally planned for Wednesday February 24, 2016.
As of this writing, no new launch date/time has been announced. Per SES's Twitter feed: SES and SpaceX are now targeting to launch #SES9 on Sunday, 28 February, at 6.46pm ET, with a backup date on Monday, 29 February. (Hat tip to gman003.)
What's the problem? Well, for one, this IS rocket science. For background, please refer to the eminently-readable explanation written by Space Shuttle Flight Engineer Don Pettit: The Tyranny of the Rocket Equation. Overcoming Earth's gravity takes a lot of energy. The greater the payload and/or the altitude, the more fuel and oxidizer you need to get there. But, that has its own mass, which requires even more power to lift. In short, something like 90%-95% of the rocket's launch mass ends up being fuel and oxidizer.
The SES-9 communications satellite is destined for GTO (Geosynchronous Transfer Orbit) That is much higher than LEO (Low Earth Orbit) where, for example, the ISS (International Space Station) orbits. The Falcon-9 is designed to deliver up to 4.85 mT (4850 kg) to GTO. This is where things get interesting. SES-9 comes in at a hefty 5330 kg — 480 kg over nominal lift capacity to that altitude. So, the challenge becomes how can SpaceX get something so massive to such a high orbit?
SpaceX has found a way to increase the lifting capacity of the Falcon-9 by using fuel and liquid oxygen that have undergone additional chilling. How does that help? The SpaceFlight Now article explains it well:
[Continues.]
The modified Falcon 9 consumes a super-chilled propellant mix that allows engineers to load additional fuel into the rocket. The cryogenic liquid oxygen is chilled closer to its freezing point, from minus 298 degrees Fahrenheit [90 Kelvin] to minus 340 degrees [66 Kelvin] , while the Falcon 9's RP-1 fuel — a refined form of kerosene — is cooled from a standard room temperature of about 70 degrees Fahrenheit to 20 degrees, according to Elon Musk, SpaceX's founder and CEO.
The change essentially allows engineers to load more propellant mass into the the volume of the Falcon 9 fuel tanks, which are also slightly enlarged on the upgraded rocket. The denser fuel mix flows faster into the rocket's Merlin engines, adding extra thrust to haul heavier satellites into orbit and leaving leftover fuel to attempt landings of the booster for future reuse.
The first stage's nine Merlin 1D engines collectively generate 1.5 million pounds of thrust at sea level, up from 1.3 million force-pounds on the earlier version of the Falcon 9. All told, the changes allow the Falcon 9 to deliver about 30 percent more mass to orbit without extra thrust from strap-on boosters or other major additions to the booster, according to SpaceX.
[...] SpaceX engineers struggled to master the handling of the super-cold densified propellants at the Falcon 9 launch pad before the maiden flight of the upgraded rocket in December, but the rocket successfully took off the first time it received propellants on a real launch attempt.
The launch team updated the Falcon 9's countdown procedures to account for the sensitivity of the super-chilled propellants.
Instead of loading the propellants three hours before liftoff, the upgraded Falcon 9 receives its fuel in the final 30 minutes of the countdown to minimize the time the cryogenic liquid sits inside the rocket tanks and warms up in the mild ambient temperatures of Florida's Space Coast.
Bear in mind that the rocket still needs to withstand the acceleration, vibration, and aerodynamic drag of launch all while keeping its payload on target and without breaking up (or exploding) in the process!
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SpaceX had originally scheduled to launch a rocket on Wednesday, February 24 but has decided to postpone the launch by at least 24 hours:
SpaceX on Wednesday postponed for at least 24 hours the scheduled Florida launch of a Falcon 9 rocket on a satellite-delivery mission and attempted return-landing at sea to allow extra time to chill the rocket's propellant, the company said.
Blast-off of the 23-story-tall booster and its payload, a SES SA communications satellite, was rescheduled for 6:46 p.m. EST (2346 GMT) on Thursday from Cape Canaveral Air Force Station, SpaceX said.
"Rocket and spacecraft remain healthy," the company said in a message posted on Twitter as the delay was announced. Hours earlier SpaceX had described weather conditions at the launch site as a "60 percent go" and said it was tracking thick clouds and high winds.
Following the delay, the company issued a further statement explaining: "The team opted to hold launch to ensure liquid oxygen temperatures are as cold as possible in an effort to maximize performance of the vehicle."
The statement left unclear how much, if any, weather was a factor in the postponement.
Meteorologists forecast an 80 percent chance that weather would be suitable for liftoff on Thursday.
I, for one, will be anxiously awaiting the launch and hopefully successful barge landing of this flight. I well remember the 60s and the progression of the Mercury, Gemini, and Apollo flights that culminated with the moon landings and return of moon rocks to earth. I followed many a space shuttle launch and landing, too. And now we see the space race heating up again. Exciting times.
(Score: 4, Informative) by gman003 on Saturday February 27 2016, @10:39PM
Per SES's Twitter feed, SES and SpaceX are now targeting to launch #SES9 on Sunday, 28 February, at 6.46pm ET, with a backup date on Monday, 29 February [twitter.com]
(Score: 2) by takyon on Saturday February 27 2016, @11:42PM
Good. With a quick rewrite, my Dewey Defeats Truman submission [soylentnews.org] won't have to die in vain.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by gman003 on Monday February 29 2016, @05:51AM
Further update: Attempt 3 aborted.
First hold was initiated at T-1:33, fouled range. There was a ship in the no-go area set up for safety reasons - the zone where a failure could lead to falling debris.
Countdown resumed when the ship left the range, went down to 0:00 but automatically aborted when an engine produced insufficient thrust on ignition. Insufficient time remained in their launch window for a turnaround, so this attempt was scrubbed. Preliminary report is that it was caused by a helium bubble - the extended sit time let the liquid helium (used to pressurize the tanks as they drain) begin to evaporate. Helium bubbles in the LOX line apparently caused the thrust problems.
Launch Attempt #4 is tentatively scheduled for 2-29 but some reports are saying 3-1. Either way, SES-9 did not go to space today.
(Score: 0) by Anonymous Coward on Saturday February 27 2016, @11:07PM
they could just use russian rocket engines like lockheed martin
rocket science is hard enough without political bullshit getting in the way
(Score: 0) by Anonymous Coward on Saturday February 27 2016, @11:11PM
All rocket engines are rushin' rocket engines.
(Score: 2, Funny) by Anonymous Coward on Saturday February 27 2016, @11:34PM
But you can't go Putin just any engines on American rockets.
(Score: 5, Informative) by gman003 on Sunday February 28 2016, @12:34AM
It's good in general for multiple groups to be designing and producing engines. We each come up with new strengths and weaknesses.
SpaceX's engines are really good at thrust-to-weight ratio. That's good for a first-stage engine, because nobody can really make a fuel-efficient (high ISP) engine at sea level, so you just pile on as much fuel as your engines can lift. They've also got some really good manufacturing techniques - if you set all other costs equal, I expect they'd be the cheapest.
NPO Energomash is good at squeezing as much ISP as possible from room-temperature fuels, and they have a nifty design that scales up the turbopump but just uses multiple combustion chambers and nozzles. They also have some nifty metallurgy behind ox-rich preburners. (And of course, they're dirt cheap because Russia's economy is in the shitter)
Rocketdyne is pretty good with LH2 - even as a first-stage engine. They hold the records for both thrust and specific impulse, although not on the same motor unfortunately. And back in the day they built the F-1, which remains the largest single-chamber rocket engine ever made.
MHI and Snecma are both starting to give Rocketdyne a run for their money on LH2.
Thiokol is good with solid rocket motors, that one incident notwithstanding. Solid boosters pair well with LH2 first stages, so they've got a solid (NPI) niche.
CALT is the only one actively developing large-scale hypergolic engines - everyone else moved on to RP-1 or LH2 (or solids, for their ICBMs), but CALT is still big on them. Like many others, I suspect that's a dead end, but maybe it isn't, so it's not a bad thing to have them working on.
Both SpaceX and Blue Origin are working on LCH4, which seems like a quite promising fuel - combining most of the advantages of LH2 with most of the advantages of RP-1. Maybe it won't pan out, but maybe it will.
(Score: 1, Interesting) by Anonymous Coward on Sunday February 28 2016, @09:18PM
Propane looks better than methane, or cyclopropane if you don't mind the cost.
There is something to be said for RP-1 with pre-decomposed peroxide. This is a hypergolic mixture, the only one with low toxicity. (not a monopropellant, which is just dumb) When the hot steam and oxygen hits the RP-1, it ignites. The turbopumps are also easy to power.
(Score: 2) by gman003 on Monday February 29 2016, @12:02AM
Chemically speaking, what you want for maximum specific impulse is for as much of your exhaust mass to be hydrogen as possible. Straight hydrogen is a deep cryogenic fuel, requires a pretty substantial mass of insulation to keep it from boiling off, and it has some tricky metallurgical requirements. Methane gives as much hydrogen as possible for a hydrocarbon - 4:1 H:C ratio - and makes it a much, much nicer compound to work with. Liquid methane is actually above liquid oxygen in temperature, so other than some viscosity issues, it's easy to deal with. Liquid propane is an 8:3 H:C ratio, much worse - although still better than RP-1. I'm not sure exactly what benefit LC3H8 gives over LCH4, other than maybe cost, and propellant is already the cheapest part of the launch.
Interesting tidbit on the RP-1 + H2O2 being hypergolic... did not know that. HTP is a bitch and a half to work with, though; I'm not surprised nobody's using it.
(Score: 4, Funny) by Fnord666 on Sunday February 28 2016, @02:50AM
I thought the correct term was "spontaneous disassembly".
(Score: 2, Informative) by Some call me Tim on Sunday February 28 2016, @05:09AM
The last time I heard it mentioned, it was called RUD. Rapid, Unscheduled, Dis-assembly. :-)
Questioning science is how you do science!
(Score: 3, Informative) by engblom on Sunday February 28 2016, @11:03AM
I'm sure I'm not the only one who had to check up how ET is related to UTC. Apparently ET is UTC-5.
Editors, please, give the time in UTC in future as everybody in a scientific community knows how their time zone relates to UTC.
(Score: 0) by Anonymous Coward on Sunday February 28 2016, @09:20PM
You need to be in Florida to see the launch. Local time is appropriate.
(Score: 1) by kurenai.tsubasa on Monday February 29 2016, @01:10AM
I tuned into the webcast a bit too late to get it live on Youtube [youtube.com]. T0 at 53:31. I haven't found anything about whether this changes the Monday window. Currently the reason for the launch abort during ignition is unknown.