The flight of STS-121 (ISS Mission ULF-1.1) opened with the liftoff of Space Shuttle Discovery from Launch Complex 39-B , Kennedy Space Center, at 1:36 PM CDT (18:36 GMT) on 4 July 2006. Appropriately, this was American Independence Day as well. After some 9 minutes of powered flight, MECO (Main Engine Cut Off) occurred, and orbit was achieved.

As with the previous Shuttle flight, STS-114, a great deal of attention was focused on the performance of the foam insulation (PDF file 522kb) on the External Fuel Tank. Changes and modifications to this component were successful, and after extensive on-orbit inspection of the heat shield, NASA engineers pronounced Discovery safe for re-entry at mission end.

Docking with ISS was accomplished on 6 July, roughly two days after launch. The CREW of Discovery were welcomed by ISS Expedition 13 Commander Pavel Vinogradov, and Flight Engineer Jeffrey Williams, in the traditional Russian way, with the offering bread and salt. This flight also delivered ESA (European Space Agency) Astronaut Thomas Reiter, of Germany, to join the ISS Expedition 13 crew. His addition marked the first time ISSy has boasted a crew of three since spring 2003, following the loss of Columbia.

Discovery brought with her the Italian built MPLM (Multi-Purpose Logistics Module) "Leonardo". This spaceborne "moving van" contained around 15 tons (13,600kg) of equipment and supplies for ISSy. Once the new materiel was unloaded, superfluous equipment crowding the limited space aboard ISSy was stowed for return to Earth.

Three EVAs (Extra-Vehicular Activity or spacewalk) were mounted in US spacesuits from the Quest Airlock. Astronauts Piers Sellers and Michael Fossum tested methods for repairing damaged heat shield components, and performed repairs to the Mobile Transporter, damaged by accident in December 2005. In addition, the two Astronauts tested the feasability of using the 50 foot (15.24m) robotic arm extension. This extension was used with a special camera to inspect the belly of the orbiter for damage. In this case, engineers at Houston wanted to know if extended arm could be effectively used to carry Astronauts on the end. It was hoped that they would be able to work from this lofty perch. The experiment was a success.

After some nine days of joint operations with the ISSy crew, farewells were made, and Discovery separated from ISSy at 4:08 AM CDT (9:08 GMT) 15 July 2006 to fly solo for

the next two days. STS-121 came to an end with the safe landing of Discovery at the KSC Shuttle Landing Facility , runway 15, at 8:15 AM CDT (13:15 GMT) on 17 July 2006. This mission was highly successful, the brave crew accomplishing every task mapped out for them. Total duration: 12 Days 18 Hours 38 minutes. The fact that Discovery and her crew performed so flawlessly also opened the door for the resumption of ISS construction flights again. These had been suspended since the fatal loss of Columbia in February 2003. Congratulations are in order for all concerned.

On 4 July 2006, after Discovery attained orbit, the External Fuel Tank was jettisoned. It was left to fall out of orbit and burn up in the atmosphere. In the process of separation, a very large piece of ice came off the tank. This strangely shaped chunk of frozen water had formed on the tank from condensation due to the extreme low temperatures of the liquid fuels it carried. (Liquid Hydrogen - H2 ..&.. Liquid Oxygen - O2) This ice was tumbling in space, and parts were breaking off as well. It's appearance was rather weird as it changed its appearance constantly. I just thought you might like a chance to see this oddity for yourself.

This frame shows the recently jettisoned External Tank. It was tumbling and rapidly falling away from Shuttle Discovery. After a relatively short period of time, it was lost to sight.

Here is the monster ice "chip". It changed its aspect with every movement. One of the frames used in this animation even resembles the skeleton of a whale to me.

All of the photos and videos of these happenings were taken by Astronauts Mike Fossum and Lisa Nowak using hand held cameras. They did a difficult job very well, didn't they?

I hope you enjoyed this look at an unusual occurrance during the launch and ascent of STS-121. Sometimes we need to see what is ordinary, yet strange, to become more familiar with the odd things which can happen in space travel. This helps us to do better at picking out those things which don't have normal explanations.

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© 2006 Jeff Challender