On 1 October 2014, communications with the STEREO-B spacecraft were interrupted during a planned test in anticipation of its solar conjunction at the Sun's farside (see image underneath for positions relative to Earth). Despite intense recovery efforts in the subsequent months, contact could not be re-established and the spacecraft seemed to be lost. More background information can be found in the news items of 4 June 2014 and 29 July 2015.
So it came as a big surprise when late on 21 August, during its monthly recovery operation, the NASA Deep Space Network (DSN) managed to lock on a frequency transmitted by STEREO-B's low gain antenna. In the subsequent days, analysis revealed the spacecraft was in a complex spin, with its fuel tanks frozen and the battery state of charge at 30%. The prime goal is now to fully recover battery power and gradually thaw STEREO-B's instruments and fuel tanks from its deep freeze. It may be clear that the spacecraft is still in a critical condition and that it will take quite some time before imagery, such as those from its twin STEREO-A, will be available again.
It is interesting to note that, once again, the Goldstone radio telescopes played a crucial role in re-establishing contact with a lost spacecraft. Indeed, back in 1998, it was also this 70-meter radio "dish" that in cooperation with the Arecibo telescope (305 meter, Puerto Rico) managed to get an echo from the -at that time- silent SOHO. Eventually, recovery was succesful and SOHO became one of the finest solar observatories ever. See here for the entire story on "SOHO's holiday". Though STEREO-B has been deep-freezed much longer than SOHO (resp. nearly 22 months vs. about 2 months), hopes are that STEREO-B's recovery will be as fortunate as SOHO. The latest in STEREO-B's revival can be found at their website.
