Construction began on Columbia in 1975 at Rockwell International’s (formerly North American Aviation/North American Rockwell) principal assembly facility in Palmdale, California, a suburb of Los Angeles. Columbia was named after the American sloop Columbia Rediviva which, from 1787 to 1793, under the command of Captain Robert Gray, explored the US Pacific Northwest and became the first American vessel to circumnavigate the globe. It is also named after the command module of Apollo 11, the first crewed landing on another celestial body. Columbia was also the female symbol of the United States. After construction, the orbiter arrived at Kennedy Space Center on March 25, 1979, to prepare for its first launch. Columbia was originally scheduled to lift off in late 1979, however the launch date was delayed by problems with both the RS-25 engine, as well as the thermal protection system (TPS). On March 19, 1981, during preparations for a ground test, workers were asphyxiated while working in Columbia’s nitrogen-purged aft engine compartment, resulting in (variously reported) two or three fatalities.
It's hard not to like Sagittarians, for their openness, generosity, and sociable nature. They are deep thinkers in search of universal wisdom, attracting them to philosophy and religion. Their minds can grasp both the details and the bigger picture: they can think with intellectual precision but also intuitively. That unusual combination of thinking skills allows them to be at the forefront of creative ideas. They are idealistic and care about the state of the world, leading them to take up vocations in medicine, education, religion, and politics. They need to be highly independent in their work and in their personal lives.
Dr. Porco further believes that Enceladus's orbit could have been much more eccentric in the past. The greater the eccentricity, the greater the tidal squeezing, and the resulting structural variations produce heat. In this case, the heat would have been saved inside the icy moon, melting some of the ice to replenish the liquid water sea. Dr. Porco continued to explain that "(T)he tidal flexing occurring now is not enough to account for all the heat presently coming out of Enceladus. One way out of this dilemma is to assume that some of the heat observed today was generated and stored internally in the past... (N)ow that the orbit's eccentricity has lessened, the heat emanating from the interior is a combination of heat produced today and in the past."
"We don't know how long the Dagwood-sandwich structure would exist. This structure represents a stable state, but various factors could mean the moon doesn't reach this stable state," Dr. Christophe Sotin said in a May 1, 2014 statement. Dr. Sotin is of the JPL.