HELSINKI - After a decade of preparations, the European Space Agency and the Chinese Academy of Sciences are about to launch a spacecraft that will stare at Earth's magnetic shield and figure out how it works. Because apparently, our planet's invisible force field isn't as reliable as we'd like.
The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission - and yes, they really went with that acronym - is set to lift off on a Vega C rocket from Kourou, French Guiana, at 11:52 p.m. Eastern on May 18 (0352 UTC May 19). The 2,200-kilogram spacecraft, including 1,500 kg of propellant, will spend about a month burning 90% of its fuel to get into a highly elliptical orbit that takes it 121,000 kilometers above the North Pole. From there, it will use wide-field X-ray and ultraviolet cameras to watch the sun mess with our planet's magnetic field.
The mission was selected competitively in 2015 from 13 proposals, meaning this is the science equivalent of a reality show winner. Its goal: understand how the magnetosphere protects us from solar wind and coronal mass ejections, and when it fails - because it does fail, and the results are not pretty.
"By actually seeing that shape, by seeing that whole region, we're going to get a far better understanding of this interaction between the Sun and the Earth," said Colin Forsyth, SMILE's European co-principal investigator, during a pre-launch press conference on March 26. He added that the magnetosphere "deflects these charged particles around us. It captures some of them, and it protects us from these charged particles, from actually getting down into our atmosphere and causing major problems."
Those "major problems" include the 1989 geomagnetic storm that knocked out Quebec's power grid and the 1859 Carrington Event - the most intense solar storm in recorded history - which set telegraph systems on fire and lit up the skies with auroras. A similar event today would imperil spacecraft, astronauts, and cause economically devastating electronic disruption on the ground. So yeah, understanding this stuff matters.
SMILE will provide the first global X-ray imaging of the magnetosphere using something called solar wind charge exchange emission - which is a fancy way of saying it will catch the X-rays produced when highly charged solar wind ions run into neutral atoms. The soft X-ray instrument, developed by the UK's Leicester University, uses lobster-eye optics and some of the largest CCDs ever flown in space, which must be cooled to minus 120 degrees Celsius. Because of course nothing is easy in space science.
The mission marks the first time ESA and China have jointly designed, implemented, launched, and operated a space mission. ESA is providing the launch and payload module (with Airbus as prime contractor), while CAS is responsible for three scientific instruments and mission operations. Data will be sent to the O'Higgins Antarctic ground station operated by DLR and China's Sanya ground station. ESA science director Carole Mundell noted that the collaboration demonstrates how science can unite teams across political divides - which is nice, given that ESA has shelved plans to send astronauts to China's Tiangong space station and China's partnership with Russia largely precludes cooperation in lunar exploration.
The mission was originally scheduled to launch in 2021 but faced delays due to export control assessments, COVID-19, and a technical issue on a subsystem component production line that postponed the April 9 target. The delays mean SMILE will miss the once-every-11-year solar maximum, though it's still close enough for its science objectives. The Vega C launch will be the seventh for the rocket, and the first where Italian company Avio takes on the launch operator role.
SMILE will spend about 40 hours of each 2-day orbit observing the impacts of solar wind and coronal mass ejections on Earth's magnetosphere and ionosphere, plus 45-hour continuous aurora observations. But don't expect real-time space weather alerts - this mission is about understanding the underlying physics, not giving you a heads-up before your GPS goes haywire.