With more launches than Russia last year, Elon Musk’s rocket company SpaceX made waves in 2017. It also tore a hole in the ionosphere.
Scientists have determined that the launch of the company’s Falcon 9 rocket on Aug. 24 punched a temporary hole into a layer of the Earth’s atmosphere nearly 560 miles wide.
While the effect is not permanent, here is how the rocket impacted the ionosphere and what it means as humans move forward with space flight.
What is the ionosphere?
The ionosphere is the layer of our planet’s upper atmosphere between 75 km and 1000 km (or between 46 and 621 miles) where the sun’s energy and cosmic radiation ionize atoms. The solar and cosmic rays strip atoms in the area of one or more of their electrons, giving them a positive charge and leaving the electrons to act as free particles.
This is the part of the atmosphere where auroras occur. It overlaps the mesosphere, thermosphere, and exosphere.
The ionosphere is important because the concentration of ions and free electrons allows it to reflect radio waves. This facilitates radio communications across distant points on Earth as well as between satellites and Earth.
During the day, X-rays and UV light from the sun provide energy that continuously knocks electrons from atoms, creating ions and free electrons. These separate particles are constantly colliding, recombining, and becoming electrically neutral atoms again. So at night, without the energy from the sun, more particles combine than are ionized and the ionosphere shrinks. While the cosmic radiation still affects this part of the atmosphere, only the atoms at the upper portion continue to be ionized.
What happened during the SpaceX launch?
Rather than fighting the force of gravity to fly straight up into the sky, rockets normally take a curving trajectory and travel nearly parallel to the planet’s surface at about 80 or 100 km above the Earth. This allows the space crafts to carry larger and heavier objects into orbit than would be physically possible with a vertical flight path.
For the Formosat-5 mission SpaceX flew in August 2017, the Falcon 9 rocket was carrying an Earth observation satellite for Taiwan’s National Space Organization that weighed just 475 kg — a light payload for the Falcon 9.
Since the satellite was light enough, the rocket took a nearly vertical path into space. This caused the Falcon 9 booster and second stage to create circular shockwaves and punch the large hole through the plasma of the ionosphere. The 559-mile hole lasted for up to three hours.
Is this a problem?
The hole caused by the SpaceX launch was only temporary, but as commercial rockets take more and more satellites into orbit, the disruptions in the ionosphere will happen more often. Private space companies received $3.9 billion in private investments during 2017 and the industry is projected to be worth nearly $3 trillion by 2040.
One consequence of this growth and an increased number of rockets tearing through the atmosphere could be errors in global position system (GPS) navigation, scientists say.
When the Falcon 9’s second stage rocket burnt through plasma in the ionosphere and created the hole about 13 minutes after launch, it likely caused about a one-meter error in GPS programs, according to a paper in Space Weather.
The lead author of the study, Charles C. H. Lin from the National Cheng Kung University in Taiwan, describes a rocket launch like a small volcano erupting, unloading energy into the middle and upper atmosphere in a way that’s comparable to what we see from a magnetic storm.
Currently, the impact from a single launch remains relatively insignificant.
“Without considering the rocket launch effects, there are errors from the ionosphere, troposphere, and other factors that will produce up to 20-meter errors or more,” he told Ars Technica.
But the impact will grow as space technology continues to develop.
“Humans are entering an era that rocket launches are becoming usual and frequent due to a reduced cost by reusable rockets,” Lin said. “Meanwhile, humans are developing more powerful rockets to send cargoes to other planets. These two factors will gradually affect the middle and upper atmosphere more, and that is worthwhile to pay some attention to.”
