Uhuru, also known as the X-Ray Explorer Satellite or SAS-1 (for Small Astronomical Satellite) was an orbiting observatory, specifically for X-ray astronomy (the first of its kind). It was launched from the Italian San Marco offshore launch platform off the coast of Kenya on December 12th 1970, Kenyan independence day, hence the post-launch choice of a new name, which, as all good Star Trek fans know, is the Swahili for “freedom”. Its three year mission was to seek out new X-ray sources via a survey of the entire sky.
Uhuru was the first US satellite to be launched by another country. Under the terms of a memorandum of understanding between NASA and the University of Rome, the Americans provided the rocket and satellite, while the Italians were responsible for the assembly and launch (following training with NASA in Virginia). The site was chosen principally to enable easier access to an equatorial orbit than would be possible from Cape Canaveral (which would have needed a much larger rocket).
The joint mission was very successful, with Uhuru producing a catalog of some 300 X-ray objects during its three years, mostly binary systems and supernova remnants.
On a completely unrelated topic that has nothing at all to do with astronomy or spaceflight, but might appeal to Star Trek fans of a certain vintage, December 12 1970 is also notable in Twin Peaks circles, as it marks the birthday of Mädchen Amick (Shelley Johnson).