SpaceX CRS-3 and re-light after MECO

In spite of thundershowers just hours before, a SpaceX Falcon 9 rocket carrying a Dragon spacecraft launched on time at 3:25:21 pm EDT on Friday, April 18, and headed for rendezvous with the International Space Station (ISS). The rendezvous dictated the length of the launch window:  1 second. In essence, any delay would have meant scrubbing the launch for the day. The launch was flawless.

SpaceX-CRS-3_Falcon_9_liftoff

Launch of Falcon 9 on SpaceX CRS-3 mission to ISS. April 19, 2014. (Image source: SpaceX)

For NASA, this is the third SpaceX Commercial Resupply mission (SpaceX CRS-3). It is one of 12 that NASA has contracted SpaceX to perform. These launches are conducted from Cape Canaveral, FL. The other CRS provider is Orbital Sciences, which launches its rockets from Wallops Island, VA, about 100 miles SE of Washington, DC.

This Dragon spacecraft had been heavily upgraded with new avionics and power so that it could accommodate new biological payloads to be sent to the ISS. A few hours before launch, under severe weather conditions, the SpaceX crew loaded the last of the time-sensitive payloads into the Falcon 9.  The whole assembly was then stood erect and the rocket loaded with propellant. The countdown was uneventful. The only concern was the weather, which amazingly was beginning to cooperate.

Following main engine cut-of (MECO) at 2:45 (m:ss) into the flight, the first stage was cast off, and the second stage took over the mission. But sometime later, the first stage came back to life. The stage turned around and the engine (well, at least one of the nine) was re-lit, cutting short the trajectory taking it far into the Atlantic. With most of the horizontal speed burnt off, the stage now fell into re-entry, subjected to plasma flow that does bad things to most materials. But after re-entry, some number of engines were lit again, slowing its descent further, and allowing landing legs to deploy about 10 seconds before hitting the water. Some 8 seconds after hitting the water, the on-board computers finally stopped transmitting when the stage went horizontal.

Meahwhile, back in space, the Dragon is due to dock with the ISS on Easter Sunday. The biologicals include a Vegetable Production System (VEGGIE), capable of producing salad-type vegetables in space; and the T-Cell Activation in Aging experiment, probing the cause of a depression in the human immune system in microgravity.  It also carries a laser communication experiment and 5 CubeSats for later deployment.

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