Emily LakdawallaAug 03, 2007

Go, go Phoenix! 18 hours until launch...

Well, here we go; the once-every-two-year event of a spacecraft deprarture from Earth toward Mars is less than a day away, weather permitting. The original launch date (today) would have given my daughter the biggest candle ever to light her first birthday cake, but that was not to be. Now I REALLY hope that the launch will go off tonight, if only for the selfish reason that I do not want to have to wake up more than once at 2 in the morning to see if the thing is really going to go. (Once upon a time, I would have stayed up to watch the launch, but with at least one family member going to bed at 7:30 it now seems a better plan to try to get a few hours' sleep in before the rocket ignites.)

I went through the Phoenix mission press kit yesterday in an attempt to compose a timeline for the launch story that Amir Alexander posted but I'm afraid that details on the timing of launch events were unusually scanty. The best I can do is to take the launch timeline I wrote for Dawn -- which has the same exact events, though not the same exact durations -- and fill in the few skimpy timing details that were provided in the Phoenix press kit. So here you go.

Time (EDT)Time (UTC)
The launch window is about 27 minutes long. At liftoff, the first stage of the rocket and six of the nine solid rocket boosters ignite.
First six solid rocket boosters burn out
The first stage of the rocket is still firing as the six solidsburn out.
Remaining three solid rocket boosters ignite   
Burned-out solids separate
This happens as the first stage and three solids continue to fire. The separation of the six burned-out solids happens three at a time, with one second elapsing in between the separation events.
about 105:2809:28
Remaining three solids burn out   
Remaining solids separate
The last of the solid rocket boosters fall off as the rocket passes through an altitude of 73 kilometers (45 miles).
about 205:2909:29
First stage shutoff
The main engine cuts off as the rocket passes through an altitude of about111 kilometers (69 miles).
First stage separation   
Second stage ignition   
Payload fairing jettison
The nose cone of the rocket splits in half and falls away,and the Phoenix spacecraft is exposed to space for the first time.
Second stage shutdown
Thereis a pause in the middle of the firing of the second stage; the spacecraftcoasts until it has reached exactly the right position in Earth orbitto begin the journey to Mars.
about 9:2005:3809:38
Second stage restartabout 7206:3910:39
Second stage shutdownabout 7406:4110:41
Thrusters spin up the spacecraft to 70 revolutions per minute
The spacecraft is spun in order to stabilize it for its onward journey.
Second stage separation   
Star 48 upper (third) stage ignition
At last, Phoenix will fly fast enough to escapeEarth's gravity and head into interplanetary space.
Star 48 burnout   
Spindown to zero
Ayo-yo despin system will counteract the spacecraft's spin.
Third stage separation
The spent third stage falls away at an altitude of 1,016 kilometers (631 miles).
about 8406:5110:51
Goldstone DSN station establishes communication
After waiting a little more than 8 minutes for the liquid xenon to swirl to a stop, the spacecraft's hydrazine attitude-control thrusters will counteract whatever spin the spacecraft gained from the process.
about 9006:5710:57

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