The 4 equal satellites of the Cluster II mission studied the interaction of the photograph voltaic wind with Earth’s magnetic topic. Credit score rating: ESA – CC BY-SA 3.0 IGO
On July 26, 2000, the European Home Firm (ESA) launched the Salsa satellite tv for pc television for computer, which joined its three companion satellites — Samba, Rumba, and Tango — on the Cluster II mission, scheduled to closing two years. On Sep. 8, after larger than 24 years of service, Salsa re-entered Earth’s setting in a managed de-orbit, the place it broke up over the South Pacific Ocean.
Cluster II was designed to overview Earth’s magnetic topic, significantly how the photograph voltaic wind interacts with it to offer aurorae and geomagnetic storms. The satellites investigated charged particles and magnetic fields all through enormous swaths of the magnetosphere from as shut as 10,000 miles (16,000km) above Earth’s ground out to 120,000 miles (75,000km) — roughly halfway to the Moon.
Related: Are we ready for the next massive photograph voltaic storm?
Cluster II was a near-identical substitute to the distinctive Cluster mission, which was destroyed in a failed launch in 1996. The equal, spinning, drum-shaped satellites of Cluster II flew in a tetrahedral formation and can maneuver commonly, sometimes bunching as shut as 2.5 miles (4 kilometers), nevertheless usually spreading out all through some 6,200 miles (10,000 km) in home.
Each craft carried a group of gadgets for measuring the facility and density of charged particles and electromagnetic fields and waves, and performing analysis on the stormy home local weather the craft sailed by way of.
The goal of these gadgets was to overview the small-scale development of Earth’s plasma setting, significantly the photograph voltaic wind-magnetosphere interaction. Significantly, the mission was designed to map and analysis the various strategies by which Earth’s magnetotail space altered its magnetic topic and plasma circumstances by way of the passage of a coronal mass ejection, a burst of cloth the Photo voltaic typically flings into home at extreme speeds.
All through excessive geomagnetic storms, particle and topic circumstances fluctuate shortly in every time and home, which makes in-situ measurements important in understanding this train. Cluster II carried out these measurements with aplomb, providing data all through larger than two full cycles of accelerating and decreasing photograph voltaic train (a photograph voltaic cycle is roughly 11 years). Researchers shall be mining the data for years to return.
Flying in formation
Cluster II wasn’t the first or the ultimate mission that consisted of explicit particular person satellites working in a flying constellation. Noteworthy amongst these are the Geostationary Operational Environmental Satellites (GOES), which have been periodically updated and altered as a result of the primary launch in 1975. GOES is answerable for monitoring home local weather and Earth’s setting, and has even aided in search and rescue missions.
The 5 satellites of NASA’s Time Historic previous of Events and Macroscale Interactions all through Substorms (THEMIS) mission have been launched in 2007 to overview magnetic reconnection in Earth’s magnetic topic. The NASA mission might fluctuate the separation distance of the maneuverable equal satellites to overview many different scales of the magnetic reconnection phenomenon. Whereas three of the satellites keep in Earth orbit, two now orbit the Moon, to overview home local weather there.
And naturally many communication satellites fly in formation, from GPS to Starlink, to produce safety all through Earth’s ground.
A superb life
Cluster II was not designed to be operational perpetually. A satellite tv for pc television for computer like Salsa on the end of its lifetime cannot be allowed to remain in home to alter into particles for an extra spacecraft to bump into, nor allowed deplete inside the setting by mere chance, its objects in all probability falling on populated areas. So ground controllers carried out a group of maneuvers to ship Salsa proper right into a managed re-entry Sep. 8.
Related: Small, untrackable objects of home junk are cluttering low Earth orbit
Even all through their closing months of operation and atmospheric re-entry, the 4 Cluster II satellites gave scientists a ring-side seat to take a look at the mysterious space the place charged particles are accelerated sooner than producing the polar aurora. These areas are too extreme for analysis by balloon payloads and too low to be studied by spacecraft in safe low Earth orbits.
The remaining spacecraft of the Cluster II constellation shall be de-orbited over the next two years, nevertheless with Salsa’s re-entry, the mission’s science operations have ended. Over 3,200 evaluation papers have been written and printed thus far regarding the Cluster II science accomplishments, they usually’ll definitely proceed to produce notion for years to return.