STEREO Solar Conjunction - HD

Since February 2011, the two spacecraft of NASA's the Solar Terrestrial Relations Observatory or STEREO mission have been providing scientists with unprecedented views of the far side of the sun.

The spacecraft travel at different speeds. This means that over time, the satellites become increasingly out of sync, appearing from Earth's perspective to drift farther apart, able to observe first the sides and eventually the far side of the sun. Now they are nearing each other once again, this time on the other side of the sun. During this period when the sun blocks Earth's view -- a geometrical position known in astronomy as a superior conjunction -- radio receivers on Earth will not be able to distinguish STEREO's signal from the sun's radiation. Communication with the spacecraft will cease and the satellites will both go into safe mode without collecting data for a time. This will happen for STEREO-Ahead from March 24 to July 7, 2015. STEREO-Behind will be in superior conjunction from Jan. 22 to March 23, 2015. At least one spacecraft, therefore, will always be collecting data.
Before this occurs, the heating from the sun will also begin to affect - though not shut down -- data collection. From wherever they are in space, the STEREO spacecraft aim their antenna toward Earth to send down data. This position puts the antenna fairly close to pointing at the sun, exposing the instruments to more heat than it can safely bear. The antenna can be adjusted to point in different directions, but the signal coming to Earth will be much fainter and won't allow for as much data to be downloaded. This antenna adjustment will begin on Aug. 20, 2014, for the STEREO-Ahead spacecraft and on Dec. 1, 2014, for STEREO-Behind.

Credit: NASA/Goddard Space Flight Center