Sunday, August 23, 2009

NASA Clears Discovery for Launch on Tuesday

NASA's mission management team met today and gave the space shuttle Discovery their official go for launch as workers ready the vehicle for an early Tuesday morning launch from America's Space Coast.

The management team met early today for a lengthy discussion on several key issues which needed to be cleared prior to giving the "go" for launch.

A few items of concern actually have been of issue for the past several weeks.

First, they included the ever present external tank foam problem. Ever since the Columbia breakup in 2003 due to foam which broke off during launch and punched a whole under the orbiter's wing, NASA has worked the continuing issue of foam breaking off and striking the shuttle during the climb to orbit. Even a .30-inch size piece of foam can cause major belly damage as it slams into the fragile thermal protection system at speeds of over two thousand mph.

The foam acts as an insulator for the super cold (cryogenic) fuels located in two inner tanks of the rust colored external fuel tank.

Kennedy Space Center technicians over the past month have performed sample foam tests to check for loose areas which could break off due to the violent nature of launch.

Mike Moses, Chairman of the Mission Management Team, said late today, "We still have a lot of work to do" in ensuring that future tanks have strong, safe insulation.

Next, the team discussed an issue with an electrical box which houses the power bus system for the orbiter's reaction control system. The forward power control assembly (FPCA) was described by Moses as "one step upstream from a circuit breaker in your house".

One of three FPCA's failed earlier this month and was replaced with a backup unit. It's the job of the FPCA to power control the forward reaction control thrusters or RCS jets; the orbiter docking system; and several items in the payload bay. The possibility of a bent electrical connector is a problem in which if you turn an item on, you may not be able to turn it off.

"How do we know if the box is o.k.? We don't...," Moses confirmed.

The real concern for the team is the RCS jets. Normally, the orbiter's flight crew disables the thrusters just after reaching space and then enables them prior to its arrival at the space station so that it can perform a number of maneuvers for docking. On this flight of Discovery, the crew will leave the RCS thrusters in the "on" position, and disable them just after docking two days into the flight.

NASA feels confident that they will be able to turn off the thrusters following docking. A thruster that accidentally fires during joint docked operations could cause damage and injury.

Last, the team outlined the weather conditions here at the Kennedy Space Center beginning on Monday afternoon and up into the 1:36:04 am EDT launch time.

Weather at the time of fueling of the external tank is expected to be 60% favorable tomorrow. Lightning within 5 miles of the launch pad and anvil clouds is the main concern for Air Force Weather Officer Kathy Winters, who was also a member of the MMT meeting today.

"Tanking (fueling) weather is what we will be watching," Winters stated late today. "As we get to tanking, the weather should be improving." Fueling is expected to begin at 4:20 pm, weather permitting.

Winters also stated that Discovery's launch time weather is 80% favorable; and that the two transAtlantic abort landing sites - Zaragosa and Maron - look good weather wise.

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