Why was the magnetic storm that caused the Starlink satellite crash unpredictable?

by NASA Goddard Space Flight Center

In February 2022, 38 artificial satellites of the satellite Internet ' Starlink ' provided by space development company SpaceX were affected by a magnetic storm at the time of launch and re-entered the atmosphere. A research team led by Ryuho Kataoka , an associate professor at the National Institute of Polar Research , has published a paper analyzing the reasons why such a situation has occurred.

Unexpected space weather causing the reentry of 38 Starlink satellites in February 2022
https://eartharxiv.org/repository/view/3208/

About the crash of 38 Starlink satellites | Ryuho Kataoka | note
https://note.com/ryuhokataoka/n/nda700de4d7a7

SpaceX launched 49 Starlink satellites from the Kennedy Space Center in Florida at 18:13 ( Universal Time ) on February 3, 2022. These satellites were originally planned to be deployed in an orbit 210 km above the ground, which is lower than the operating orbit, and then ascend to a low earth orbit 340 km above the ground. 50% more than that. As a result, the satellites were unable to ascend normally, and as a result, 38 of the 49 satellites re-entered the atmosphere.

'40 Starlink satellites may re-enter the Earth's atmosphere,' SpaceX announces-GIGAZINE

by Official SpaceX Photos

Cases of satellite crashes due to the effects of geomagnetic storms have long been known. In July 2000, the Japanese observation satellite ' Asuka ' collapsed due to the expansion of the Earth's atmosphere due to a huge solar flare , and in March 2001, it re-entered the atmosphere .

When the geomagnetism is disturbed by the influence of solar flares, the temperature and density of the atmosphere increase and the drag applied to the satellite increases, which may cause the attitude to collapse or re-entry into the atmosphere. Therefore, geomagnetic observations and predictions that may affect satellites are being carried out, but the geomagnetic storm on February 4, which affected the Starlink satellite, could not be predicted, and Kataoka et al.'S research The team analyzed why something like this happened.

According to Kataoka et al., It was the coronal mass ejection that occurred at 23:32 (Universal Time) on January 29, 2022, that caused this geomagnetic storm. Coronal mass ejections are a phenomenon in which a mass of plasma is suddenly emitted from the sun into the interplanetary space, and Mr. Kataoka predicts that 'a magnetic storm may occur in a few days' at this point. I did.

A coronal mass ejection toward the earth for the first time in a long time. A magnetic storm may occur after a few days. pic.twitter.com/ioBz1TNoWp

— Ryuho Kataoka (@ryuhokataoka) January 31, 2022

After that, it was speculated that the solar wind would end up in the air for a while and no magnetic storm would occur ...

The interplanetary shock wave did hit the earth, but it looks like a solar wind that is almost like a swing. It won't be a magnetic storm. pic.twitter.com/v0feeZWWth

— Ryuho Kataoka (@ryuhokataoka) February 2, 2022

An unexpected magnetic storm occurred at 11:00 (Universal Time) on February 3.

Oh! Contrary to my expectation, a magnetic storm is occurring. pic.twitter.com/NiYNF3i0BC

— Ryuho Kataoka (@ryuhokataoka) February 3, 2022

A typical geomagnetic storm develops within 24 hours, but this time the peak of the magnetic storm arrives again at 11:00 (Universal Time) on February 4, after the geomagnetic storm has temporarily subsided. It is assumed that the Starlink satellite in question has re-entered the atmosphere because it collided with this second peak after launch.

SBZ to repeat. This solar wind is quite interesting. I remember seeing something similar more than 10 years ago. Now that there are multiple spacecraft, it may make sense. pic.twitter.com/c3h4an0Z4M

— Ryuho Kataoka (@ryuhokataoka) February 4, 2022

In this coronal mass ejection, not only was the magnetic flux rope , which is a spiral combination of multiple twisted grounds, delayed from hitting the Earth, but also after the magnetic storm caused by the first flux rope recovered, 2 The paper states that the real flux rope arrived quite late, which was different from the standard case.

It seems difficult to accurately predict the arrival of two separate flux ropes and the solar wind profile due to coronal mass ejections, but giving up the prediction just because it is difficult can lead to great damage. I have. The paper states, 'In order to quantitatively process the structure of such minor coronal mass ejections that are difficult to predict and understand, we utilize solar wind observations by multiple probes to simulate realistic coronal mass ejections and solar winds. A new era has arrived to combine. For the safety of future satellite operations, we need a deeper understanding of the errors and limitations that can occur in cutting-edge simulations of the thermal zone. ' ..