Salsa’s last dance targets reentry over South Pacific

Launched in 2000, Cluster is a novel constellation of 4 similar spacecraft investigating the interplay between the sun and Earth’s magnetosphere—our defend in opposition to the charged gasoline, energetic particles and magnetic discipline coming from our star.

Regardless of a deliberate lifetime of two years, the Cluster mission has now spent virtually 24 years in orbit.

Over the previous two and a half many years, Cluster’s observations have led to the publication of greater than 3,200 scientific papers and counting.

They’ve supplied scientists with important insights into the sun’s affect on the Earth atmosphere and the processes happening inside Earth’s magnetosphere, and improved our understanding of probably hazardous space climate.

The sun-Earth connection stays an vital subject of research, notably throughout the present interval of excessive solar exercise.

The Cluster satellites will proceed to make observations up till September 2024. Throughout their previous couple of months of scientific exercise, they are going to move via the area through which charged particles are accelerated earlier than producing Earth’s auroras. Researchers will capitalize on the uncommon probability to check this area utilizing devices on a number of satellites on the similar time.

The many years of information saved within the Cluster science archive will proceed to allow new science lengthy after the top of the mission. With this treasure trove of information, researchers can revisit and reanalyze previous occasions, conduct new statistical analyses and implement new machine studying and synthetic intelligence methods.

Salsa’s closing steps

Of the 4 Cluster satellites (named Rumba, Salsa, Samba and Tango), Salsa would be the first to make the leap again into Earth’s ambiance.

Operators at ESA’s ESOC mission management middle carried out 4 maneuvers this January to decrease Salsa’s orbit and put together the satellite for a secure atmospheric reentry in September over a sparsely populated area of the South Pacific Ocean.

“The Cluster satellites have extremely eccentric orbits which might be strongly impacted by the gravitational pull of the sun and the moon,” says Bruno Sousa, Head of Internal Photo voltaic System Mission Operations at ESOC. “Generally, they drop steeply, by greater than 30 km in a single orbit. Different occasions, they do not drop in any respect.”

“This month, we tweaked Salsa’s orbit to verify it experiences its closing steep drop from an altitude of roughly 110 km to 80 km in September. This provides us the best attainable management over the place the spacecraft might be captured by the ambiance and start to expend.”

The timing of the maneuvers was vital. Salsa’s “eclipse season” begins in February. The satellite will spend a lot of the subsequent few months switched off whereas situated in Earth’s shadow and unable to depend on its solar arrays to generate energy.

“Salsa’s solar arrays have additionally been degrading quick because it crossed the Van Allen radiation belts. Most obtainable energy is lowering quick and will quickly attain a degree at which we’d be unable to carry out the deorbiting maneuvers,” says Beatriz Abascal Palacios, Cluster Operations Engineer.

Distinctive probability to enhance space sustainability

The remaining three spacecraft within the Cluster quartet will proceed to hold out scientific observations, with a specific concentrate on auroral physics, till September. Salsa might take part for some closing observations too, whether it is nonetheless in a position to generate sufficient energy after the eclipse season.

Like lots of our satellites, the Cluster spacecraft have been designed and launched earlier than ESA’s present tips for limiting the creation of space particles got here into impact.

Nonetheless, ESA is taking motion to reduce the environmental affect of its older missions. Final summer time, we guided ESA’s wind mission, Aeolus, again to Earth over sparsely populated areas in a first-of-its-kind assisted reentry. Because of this month’s actions, Salsa’s reentry in September will happen over a area of equally sparse inhabitants, air, and maritime visitors.

Following Salsa’s reentry, the remaining Cluster satellites will enter “caretaker” mode—managed, however finishing up no new science—till they, too, reenter Earth’s ambiance in a similar way. Rumba will reenter in 2025; Tango and Samba will reenter in 2026.

“That is the primary time that anybody has focused the reentry of a satellite with an eccentric orbit like Salsa on this approach,” says Stijn Lemmens from ESA’s House Particles Workplace. “And the top of the Cluster mission offers us the distinctive probability to reenter 4 similar spacecraft at totally different occasions.”

“The expertise we acquire from safely reentering the identical satellite at 4 totally different angles and speeds, and underneath 4 totally different units of atmospheric situations, will enormously enhance our understanding of reentries and assist us outline the usual for the secure disposal of satellites in related orbits.”