The two STEREO spacecraft will be built by Johns Hopkins University Applied Physics Laboratory (Laurel, MD).
The two STEREO spacecraft are identical and designed for a 2 year mission. Most spacecraft operations (antenna pointing control, momentum management, power management, and thermal management) are autonomous.
In May 2024, Earth experienced some of the most intense geomagnetic storms seen in recent years. Solar eruptions that led to these storms were imaged by the SECCHI HI-2 camera on NASA STEREO-A. This image sequence shows the large CME front passing over Earth (far left, not to scale) along with concurrent Kp observations, which shows the Earth's geomagnetic response to the event.
Observations from the SECCHI HI-2 camera on May 12, 2024 (top), along with the concurrent "kp" geomagnetic activity index (lower). The location of Earth is as indicated on the left of the animation. [Credits: NASA/NRL/STEREO]