Wednesday morning marked a significant event as a SpaceX rocket successfully launched, carrying two vital NASA spacecraft and one from the National Oceanic and Atmospheric Administration (NOAA).
The NASA contingent includes the groundbreaking Interstellar Mapping and Acceleration Probe (IMAP) and the innovative Carruthers Geocorona Observatory. Joining them is NOAA’s Space Weather Follow On-Lagrange 1 (SWFO-L1) mission.
All three missions are dedicated to unraveling the mysteries of the solar wind—a constant torrent of charged particles emanating from the sun—and its profound influence on Earth and the vast interstellar realm. This electrical flow is responsible for the heliosphere, an immense magnetic bubble that envelops our solar system, shielding us from potent and hazardous cosmic rays.
Specifically, the NOAA spacecraft will serve as an indispensable early warning system, alerting us when the sun unleashes powerful bursts of high-energy particles toward Earth. These solar storms pose a serious threat, capable of incapacitating orbiting satellites and causing widespread disruptions to electrical grids on our planet.
The powerful Falcon 9 rocket lifted off precisely at 7:30 a.m. from NASA’s Kennedy Space Center in Florida, just as the sun began to rise. Roughly 90 minutes later, the trio of spacecraft gracefully detached from the rocket’s second stage, beginning their individual journeys.
Each mission is destined for the same unique location in the solar system: Lagrange 1 (L1), a point positioned between Earth and the sun where their gravitational pulls perfectly balance each other. These spacecraft are expected to reach their distant destination, nearly a million miles away, by January.
Joe Westlake, director of NASA’s heliophysics division, emphasized the cost-effectiveness of this joint launch during a Sunday news conference, stating, “Having them fly together as one provides such an immense value for our American taxpayer.”
The IMAP mission alone carries a price tag of $782 million, a figure that includes $109 million allocated for its launch. Meanwhile, the Carruthers observatory is budgeted at $97 million, and the SWFO-L1 mission at $692 million.
Equipped with ten sophisticated instruments, IMAP will meticulously analyze numerous facets of the solar wind, examining the flow of particles as they stream away from the sun and traverse our solar system. A key objective is to extensively study the heliosphere, the magnetic bubble dynamically shaped by this very solar wind.
This remarkable protective bubble effectively deflects a substantial amount of the high-energy radiation originating from beyond our solar system.
Indeed, without the heliosphere’s shielding, the emergence of life on Earth might not have been possible.
David McComas, a Princeton University professor of astrophysics and IMAP’s principal investigator, highlighted the mission’s importance: ‘Understanding that shielding, why it works, how it works, how much it can vary over time is obviously very important for human exploration beyond the near-Earth environment,’ he explained, referencing future endeavors to destinations like Mars.
Among the phenomena IMAP will investigate is charge exchange. This occurs when positively charged protons within the solar wind acquire an electron upon reaching the heliosphere’s outer regions, transforming them into electrically neutral hydrogen atoms. These neutral atoms can then drift back towards the inner solar system over several years, becoming detectable by IMAP’s instruments.
While such individual charge exchange events are incredibly rare—Dr. McComas likens them to a ’10 billion-mile hole in one’—the sheer abundance of solar wind particles ensures a sufficiently high rate for IMAP to gather meaningful measurements.
Beyond this, IMAP will also be capable of detecting neutral particles that originate from outside our solar system and penetrate the heliosphere.
In a crucial role, SWFO-L1 effectively replaces the Deep Space Climate Observatory (DSCVR), which was initially launched in 2015 to provide advance warnings for solar storms. Unfortunately, DSCVR has been plagued by recurring technical malfunctions, with the most recent glitch in July rendering it offline indefinitely.
Currently, NOAA’s solar wind and storm data collection is reliant on two much older NASA spacecraft: the Advanced Composition Explorer (ACE), launched in 1997, and the Solar and Heliospheric Observatory (SOHO), launched in 1995.
SWFO-L1, however, is equipped with modernized versions of the instruments found on ACE and SOHO, promising enhanced data collection.
Initially named GLIDE (Global Lyman-alpha Imager of the Dynamic Exosphere), the Carruthers Geocorona Observatory is designed to investigate the exosphere—a tenuous layer of Earth’s atmosphere that reaches far into space, extending at least halfway to the moon’s orbit. By capturing images of this distant atmospheric layer, scientists aim to gain a deeper understanding of its interactions with the solar wind.
The fascinating discovery that the exosphere emits a glow was made in 1972, when Apollo 16 astronauts deployed an ultraviolet camera on the moon.
This glow is a result of sunlight interacting with hydrogen atoms in the exosphere. When photons from the sun strike these atoms, electrons are boosted to a higher energy level. As these electrons then transition back to their lowest energy state, the hydrogen atoms emit a distinct wavelength of ultraviolet light, known as the Lyman-alpha line.
Dr. George Carruthers, the brilliant scientist behind the Apollo ultraviolet camera, coined the term ‘geocorona’ (Latin for ‘Earth’s crown’) to describe this ethereal glow.
Following Dr. Carruthers’ passing in 2020, Paul Hertz, who then headed NASA’s astrophysics program, recognized a profound link between the Apollo 16 images and the planned studies of GLIDE. Dr. Hertz had collaborated with Dr. Carruthers early in his career, recognizing him as one of the pioneering Black scientists actively involved in space missions during the Apollo era.
In a fitting tribute, NASA officially renamed the GLIDE mission the Carruthers Geocorona Observatory in 2022.
Lara Waldrop, the principal investigator for the Carruthers observatory, explained that her team’s instrument utilizes fundamentally the same light-shifting technique from ultraviolet to visible wavelengths that Dr. Carruthers pioneered. The only significant update is the modernization of the final recording step, moving from the Apollo astronauts’ film to advanced digital sensors.
The exosphere is remarkably sparse. According to Dr. Waldrop, its densest region, approximately 300 miles above Earth, still only contains between 30,000 to 100,000 atoms per cubic centimeter. While this might sound substantial, it’s a near-vacuum; many satellites, including the International Space Station, traverse much lower, yet equally wispy, atmospheric layers.
Even more astounding, at an altitude of 50,000 miles, the exosphere’s density plummets to a mere 25 atoms per cubic centimeter, noted Dr. Waldrop, a professor of electrical and computer engineering at the University of Illinois at Urbana-Champaign.
Despite its extreme rarity, the exosphere plays a critical role in Earth’s atmospheric recovery following a solar storm. Electrons from its hydrogen atoms can occasionally ‘jump’ to high-speed protons in the solar wind, effectively neutralizing and dissipating the potent electrical currents that might otherwise cripple orbiting satellites and terrestrial power grids.
‘This crucial function was underappreciated for a long time,’ Dr. Waldrop commented.