Will Satellite Megaconstellations Destroy Earth?
SpaceX, Amazon, OneWeb, and others populate our skies with SUV-sized death machines
Satellite megaconstellations aim to provide 6G internet and other services to the world. While they might succeed, they might also destroy Earth.
A recent study by S. Solter-Hunt at the University of Iceland, published in the journal ArXiv, suggests megaconstellations might impact Earth’s magnetosphere. The magnetosphere protects Earth and its inhabitants from harmful cosmic radiation, so the news is concerning.
Estimates indicate that over the next few decades, hundreds of thousands of satellites will enter Low Earth Orbit in different megaconstellations (large groups of satellites with a shared goal). SpaceX is a pioneer in this pursuit. Solter-Hunt highlights SpaceX’s latest Starlink program:
The Starlink V2 satellite constellation (just one of many planned megaconstellations) intends to have 42,000 satellites, each the mass of a SUV, truck, or large car (1250+ kg).
OneWeb, Amazon, Telesat, and GW have similar programs. OneWeb plans to launch 6,000 satellites over the next few years.
Megaconstellations are no stranger to controversy. Astronomers find them particularly irritating. This from another paper:
astronomers pushed for reductions in the number and brightness of Starlink satellites after an image from a telescope in Chile was ruined. SpaceX responded by adding visors to the satellites, which has reduced their naked-eye visibility while still leaving them bright to telescopes.
The paper continues:
even a satellite that is unilluminated … can interfere with rapid time domain astronomy when it passes in front of a star. Radio astronomy is also threatened, since mega-constellations … require frequencies [like] those traditionally used by land stations.
Satellites create other problems when they die and reenter Earth’s atmosphere.
Megaconstellations are not built for longevity. They are mass-produced, disposable, and possess few backup systems. Starlink expects its satellites to last five to six years under ideal conditions, but many will fail earlier.
Once a satellite expires, it reenters Earth’s atmosphere for disposal. Travel back into Earth’s atmosphere is no picnic. Satellites careen toward Earth at speeds near orbital velocity, which — depending on altitude — is around 28,000 km/h (17,000 mph). It is a “violent” process that heats descending materials over 900°K (1163°F).
Reentry strips and melts aluminum, copper, lithium, and other material from spacecraft and leaves their remains in Earth’s upper atmosphere. Over 90% of satellite materials ablate in this way.
Solter-Hunt adds:
Since the beginning of the space industry, approximately 20,000 tons of material have been demolished during reentry, meaning a similar amount may still remain [in the upper atmosphere] as plasma dust.
Megaconstellations will greatly exacerbate this accumulation. Starlink anticipates 23 satellite reentries per day, which Solter-Hunt calculates is 29 tons of debris every 24 hours. She adds that since “this material is replenished every day, any potential natural decay to the ground may be negligible.”
Reentry debris has many known outcomes. Aluminum, for example, a metal commonly used in spacecraft to reduce weight, turns into alumina once dissolved in the atmosphere. Alumina can damage the ozone layer.
Space debris also precipitated a global winter that helped kill the dinosaurs. The Chicxulub asteroid shot mountains of soot and debris into the atmosphere when it struck Mexico’s Yucatan Peninsula. As Solter-Hunt notes:
research regarding the Chicxulub impact indicates that the dust from the asteroid was a key mechanism in the extinction of dinosaurs and life in this period. The space industry is replicating this type of asteroid dust with more extreme chemicals [and other elements] that have not had sufficient study at this time.
She adds that at 1250 kg per satellite, you only need “100,000 to 150,000 satellite re-entry demolishments … to meet the approximate mass of the Chicxulub impact.” Starlink would create this much debris after 12 years of consistent reentries.
As if that was not enough, metals in satellite dust are also conductive and increase ionization where found. Ionization is toxic to astronauts and electronic equipment. Solter-Hunt points to the South Atlantic Anomaly as an example:
The South Atlantic Anomoly … is a region of the [magnetosphere] that comes closest to the Earth at 200 km and is avoided by satellites due to an increase in ionizing radiation.
Megaconstellations, she continues, create a more global and “dangerous ionizing radiation zone with their reentry plasma dust.” Increased ionization imperils future astronauts and spacecraft, potentially making it unsafe to venture beyond Earth’s atmosphere.
Solter-Hunts fears conductive particles also deplete the magnetosphere. While the magnetosphere has already weakened 10 to 15% since first studied (for reasons not entirely understood), satellite debris might accelerate this decline.
Recent research suggests Mars might have lost its magnetosphere in part from conductive materials deposited by meteors.
Solter-Hunt clarifies:
Mars, nearer to the asteroid belt, may have endured more meteor ablation involving aluminium and other metals [than Earth]. This may have played a part in [its] magnetosphere erosion.
Satellites produce significantly more conductive debris than meteors. If conductive metals like aluminum eroded the Martian magnetosphere, satellites will do the same to Earth several times over.
Solter-Hunt explains how conductive debris can deplete a magnetosphere. If conductive material surrounds a magnetic field, the field weakens:
In a basic physics consideration, a spherical magnet (analog Earth) surrounded by a conductive spherical mesh (analog megaconstellations) would induce a drop in magnetic field outside of the conductive spherical mesh. This would allow solar energizing particles to more easily reach the satellite regions (and atmosphere).
Solter-Hunt notes we do not ultimately know how conductive particles will affect Earth or its magnetosphere. We do know the magnetosphere shields us from lethal solar radiation, so further research is needed.
Fortunately, we are not hopeless. While legislation is sparse and procedures loosely regulated, there are signs companies might cooperate to address concerns. Hopefully we can avoid another dust cloud like the one that ended the dinosaurs.
