NASA Plays Catch-up for Saturday Shuttle Launch

Weather Still a Concern as Shuttle Countdown Continues
The space shuttle Discovery sits atop NASA’s Pad 39B at Kennedy Space Center (KSC) in Cape Canaveral, Florida on June 29, 2006. The shuttle will launch NASA’s STS-121 mission on July 1, 2006. (Image credit: NASA TV/KSC.)

CAPE CANAVERAL, Fla. - With space shuttle Discovery set to rocket into space Saturday, pad workers are trying to make for lost time today after a short delay in launch preparations.

Shuttle pad crews are trying to recoup three hours of time, which was lost Thursday when lightning delayed plans to load Discovery with the cryogenic propellant that powers the spacecraft in orbit, NASA test director Jeff Spaulding said Friday.

"We expect to be fully caught up by the end of this morning or early afternoon," Spaulding said during a countdown briefing here at NASA's Kennedy Space Center (KSC) spaceport.

Pad workers are conducting final close outs of the cryogenic loading procedures to get back on track for Saturday's planned space shot.

Discovery is set to launch NASA's STS-121 astronaut crew on the second shuttle flight since the 2003 Columbia accident. Liftoff is currently set for 3:48:27 p.m. EDT (1948:37 GMT), though weather continues to be a concern for the planned space shot.

NASA shuttle weather officer Kathy Winters said that inland thunderstorms, coastal rain showers and anvil clouds - which can lead to triggered lightning if they stray too close to the launch pad during liftoff - still give Discovery a 60 percent chance of violating weather restrictions for its upcoming flight.

"If it comes overhead and there is active lightning, we will not be able to fly through it," Winters said of the anvil cloud threat, adding that launch regulations call for such clouds to be situated well away from Discovery's launch site.

Coastal showers tomorrow morning could impact NASA's plan to begin loading Discovery's 15-story external tank with the super-cold liquid hydrogen and liquid oxygen used to feed the shuttle's main engines during launch.

There's a 20 percent chance that rain could delay the start of external tank fueling, currently set to begin at 5:53 a.m. EDT (0953 GMT), Winters said.

Pad worker officials could delay Discovery's fuel tank loading up to about 90 minutes before the delay impacts tomorrow's planned liftoff, Spaulding added.

Meanwhile, final preparations are underway to load the last bits of cargo aboard Discovery.

Debbie Hahn, NASA's payload manager for the STS-121 spaceflight, said a batch of fruit flies and a microbe experiment will be packed inside Discovery's middeck lockers at around 3:43 p.m. EDT (1943 GMT) today.

Shuttle workers hope to roll back the shell-like Rotating Service Structure, which protects Discovery from storms and other weather at the launch pad, at about 7:00 p.m. EDT (2300 GMT), but could delay the activity for up to four hours depending on the forecast, Spaulding added.

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Tariq Malik

Tariq is the Editor-in-Chief of and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. In October 2022, Tariq received the Harry Kolcum Award for excellence in space reporting from the National Space Club Florida Committee. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. You can find Tariq at and as the co-host to the This Week In Space podcast with space historian Rod Pyle on the TWiT network. To see his latest project, you can follow Tariq on Twitter @tariqjmalik.