For the first time, an experimental treatment made from human embryonic stem cells has shown evidence of helping someone, partly restoring sight to two people suffering from slowly progressing forms of blindness.CAPE CANAVERAL, Fla. – Spacewalking astronauts relied on brute force Wednesday to remove a broken coolant pump that has hampered operations at the international space station.
Their first attempt at emergency repairs to the cooling system was thwarted last weekend by a large ammonia leak.
This time, to everyone’s relief, there was no burst of toxic ammonia from a stubborn connector, just a few frozen flakes that drifted harmlessly away.
“That’s great news,” astronaut Douglas Wheelock reported.
“That’s awesome news,” Mission Control agreed.
The urgent repair job – now expected to require two more spacewalks – is considered one of the most challenging in the 12-year history of the space station. The cooling system is crucial for keeping electronics from overheating, and half of the system was knocked out when the ammonia pump failed a week and a half ago.
Science research is on hold and unnecessary equipment is off until the pump can be replaced. Engineers suspect an electrical short in the pump led to the shutdown.
It was five hours into Wednesday’s spacewalk before the astronauts succeeded in removing the broken 780-pound pump, about the size of a bathtub. A spare pump will be installed during a third spacewalk Monday.
