Two attempts to launch last week were scrubbed by SpaceX. The launch of the SES-9 mission is now set for Sunday (Feb. 28) at 6:46 p.m. EST. If SpaceX hits another snag this evening, they’ll give it another go tomorrow evening (Monday).
What happened last week? On Wednesday, the weather wasn’t cooperating. That won’t be an issue tonight as skies are clear. The weather was better on Thursday, but there were issues loading the rocket’s liquid fuel (specifically, cryogenic liquid oxygen) in time for launch.
Let’s talk about the cryogenic liquid oxygen SpaceX uses. You might be wondering why SpaceX waits until the last second to pump the liquid oxygen to the rocket? The reason is in its name – ‘cryogenic.’
The fuel is cold, very cold. SpaceX chills the liquid oxygen to temperatures around -300 to -340 degrees Fahrenheit. To keep the fuel as cold as possible for launch, engineers wait until about 30 minutes before launch to load the fuel. They don’t want the fuel warming up in the mild winter temperatures in Florida.
Why chill the fuel at all? These extreme temperatures make liquid oxygen denser and allow engineers to load more fuel into the Falcon 9 rocket. More fuel is good for two reasons. One, the denser fuels translates into more thrust for lifting heavier satellites to higher orbits (a must since SES-9 is going into a Geostationary Transfer Orbit). And two, it gives SpaceX a bit more breathing room in the fuel department when attempting first stage rocket landings.
While SpaceX’s primary mission is getting SES-9 into orbit, everyone will be watching to see if SpaceX can finally nail a drone ship landing. Today’s drone ship is named, “Of Course I Still Love You.” A fitting name considering what SpaceX thinks will happen tonight.
In a press kit for tonight’s launch, SpaceX writes, “given this mission’s unique GTO profile, a successful landing is not expected.” That’s not to say it’s not possible. And ultimately, it’s these type of landings SpaceX wants to master. It’s not always feasible to just bring the first stage back to where it launched from. For true reusability, SpaceX needs to nail drone ship landings.
Even if tonight’s landing isn’t a success, the data gathered will help them in future attempts. The fact SpaceX is even getting as close as they are to landing them out in the ocean is impressive.
Elon Musk expects 2016 to be a solid year with a 70% landing success rate. By 2017? Hopefully 90%.
My best guess for 2016: ~70% landing success rate (so still a few more RUDs to go), then hopefully improving to ~90% in 2017