It now appears likely that space shuttle Discovery, on its final mission, STS-133 might not launch this year. A series of slips in the first week of November (Discovery was set to launch on Nov. 1 – but that date was pushed back several time to Nov. 5) was capped-off with NASA learning that not only did the orbiter’s Ground Umbilical Carrier Plate (GUCP) have a leak – but there was a crack in the foam that covers the external tank (ET). It turned out that the crack in the foam – went far deeper – and represents a far greater challenge to get the shuttle off the ground during this calendar year.
The cracked foam on the shuttle’s ET was removed on Wednesday and engineers found that there was a structural crack directly underneath. The crack is roughly 22 cm (9 inches) long and is located on the ribbed ‘stringer’ section of the ET. Cracks such as this one have been discovered on previous tanks – but none have been repaired on the launch pad. This type of damage is usually fixed back at the production facility located in New Orleans.
Previously when this problem has occurred engineers replaced the affected section with what is known as a ‘doubler.’ This is a twice-as-thick stringer section which will be put in place and new foam laid down over it.
Meanwhile, engineers have been working to figure out the cause of a hydrogen gas leak, which forced NASA mission managers to call off last week’s launch. The next launch window will open on November 30 and it will close December 6. However, with the hydrogen leak issue on top of the crack it is highly doubtful that Discovery will be able to launch by that time.