Update: Weather Permitting, SpaceX is (Still) Ready to Launch Dragon to ISS

Update:

If you happened to watch even a moment of the USF-UConn game Friday night, it was clear that an awful lot of rain was falling on Central Florida.  And in this case it stretched from the Gulf to the Atlantic coasts, including of of course, Cape Canaveral. When it became evident that a weather window would not open, SpaceX mission managers called of the launch with roughly half an hour remaining in the countdown.

The new launch attempt is 1:52 AM EDT Sunday morning.

Original story:

Following a record setting 13 day turnaround since its last launch, SpaceX is once again counting down to another launch of its Falcon 9 booster, this time carrying a Dragon spacecraft loaded with 5,000 lbs. of supplies bound for the International Space Station.

Liftoff is scheduled for precisely 2:14 AM EDT on Saturday morning, and as is the case with flights to ISS, there is no window for even the briefest of delays.  Having completed a test fire of its 9 first stage Merlin 1-D engines on Wednesday, and late loading of cargo today, the most pressing concern is for weather, with only a 50% chance of favorable conditions, due to a high level front driving moisture into the area. While strong thunderstorms are not expected, NASA anticipates a likelihood of violating thick cloud and flight through precipitation cautions. If weather or other issues prevent a liftoff, the next opportunity comes early Sunday morning, followed by dates on the 23rd and 28th.

While this particular Falcon 9 does not sport first stage landing legs, a decision driven by scheduling issues according to Vice President of Mission Assurance Hans Koenigsmann speaking at a pre-flight press conference today, it will still feature first stage engine re-ignition following stage separation, and then a SpaceX first. After re-entering the atmosphere, the booster will re-ignite a second time in order to attempt a “boost back” flight segment targeting a specific landing zone which is not on its natural descent trajectory. Waiting at sea will be a telemetry vessel, positioned to photograph the event, which will then be followed by a final decent and hover burn before the stage topples over into the Atlantic. While SpaceX is not attempting to recovery this particular booster, a successful test would set the stage for what could be a dry land recovery sometime in the next couple of flights.

According to Koenigsmann, the company is actively working with range safety to identify a recovery area, while still conducting trade studies regarding landing on a platform at sea.

Boost back will not be the only new element of this mission. The CRS-4 Dragon spacecraft is equipped for the first time with an in-house designed Environmental Control and Life Support System (ECLSS) which will be hooked to a container carrying 20 mice which NASA will be studying on orbit.  Also aboard is a highly anticipated 3-D printer, a space first, as well as a number of smaller experiments and the usual assortment of supplies. And, in an increasing sign of faith NASA is placing in commercial supply line, secured in the Dragon’s trunk is a $25 million piece of hardware, the ISS-RapidScat Scatterometer which will be used to measure ocean near-surface wind speed and direction. A full manifest can be found on the NASA fact sheet here.

If all goes well, the Dragon will target an initial orbit of 200 x 360 km, and then begin a two day transit to ISS, arriving in time for Monday berthing, the beginning a four week stay in orbit.

Live coverage begins at 1:00 AM EDT on NASA television.