Welcome to Launch Day Coverage of SpaceX’s 23rd Resupply Services Mission

CRS-23 mission -- Falcon 9 rocket and Dragon on launch pad
NASA commercial cargo provider SpaceX is targeting today at 3:37 a.m. EDT to launch its 23rd commercial resupply services mission to the International Space Station. Credit: NASA

Hello, and good morning from NASA’s Kennedy Space Center in Florida! A SpaceX Falcon 9 rocket and Dragon spacecraft stand ready for liftoff at Kennedy’s Launch Complex 39A.

Today’s launch is targeted for 3:37 a.m. EDT, less than an hour away. It is an instantaneous launch window. Live countdown begins at 3:15 a.m. – watch on NASA TV or the agency’s website. Also, you can stay right here for live coverage, through spacecraft separation.

The third flight for SpaceX under NASA’s second Commercial Resupply Services Contract, and the company’s 23rd overall cargo resupply mission, this mission will deliver more than 4,800 pounds of science experiments and research, crew supplies, and hardware to the International Space Station.

Here’s a look at some of today’s countdown and ascent milestones. All times are approximate:

Hr/Min/Sec         Event
– 00:38:00             SpaceX Launch Director verifies go for propellant load
– 00:35:00             RP-1 (rocket grade kerosene) loading begins
– 00:35:00             1st stage LOX (liquid oxygen) loading begins
– 00:16:00             2nd stage LOX loading begins
– 00:07:00             Falcon 9 begins pre-launch engine chill
– 00:05:00             Dragon transitions to internal power
– 00:01:00             Command flight computer to begin final prelaunch checks
– 00:01:00             Propellant tanks pressurize for flight
– 00:00:45             SpaceX Launch Director verifies go for launch
– 00:00:03             Engine controller commands ignition sequence to start
– 00:00:00             Falcon 9 liftoff

Hr/Min/Sec        Event
00:01:18               Max Q (moment of peak mechanical stress on the rocket)
00:02:30              1st stage main engine cutoff (MECO)
00:02:34              1st and 2nd stages separate
00:02:41              2nd stage engine starts
00:06:37              1st stage entry burn begins
00:08:38              2nd stage engine cutoff (SECO)
00:08:38              1st stage landing
00:11:49               Dragon separates from 2nd stage
00:12:35               Dragon nosecone open sequence begins

Now, let’s keep our fingers crossed for the weather! That report will be posted here shortly.