Tonight, a satellite of the POT will re-enter the Earth’s atmosphere. It is not an unusual event, given that several uncontrolled re-entries of satellites or exhausted rocket stages occur every month, but the case of the probe Van Allen Probe A is different since will not be produced in accordance with NASA’s usual safety guidelines.
Van Allen Probe A, which has spent more than a decade traversing the radiation belts of Van Allen that surround the Earth, will burn up during reentry, but it is likely that part of the satellite 600 kilograms reaches the Earth’s surface without disintegrating in the atmosphere. ‘Some components are expected to survive re-entry. The risk of harm to anyone on Earth is low.the space agency said in a statement.
1 chance in 4,200 instead of 1 in 10,000
This situation poses a risk to the population that is greater than what the United States normally allows. The risk of anyone on Earth being injured remains low, approximately 1 in 4,200, but exceeds the 1 in 10,000 standard for uncontrolled reentry to cause casualties.
‘Due to late-stage design changes, the potential risk of uncontrolled re-entry increased. After taking into account the scientific benefits of the mission and the low risk of harm to anyone on Earth, NASA granted a waiver to address non-compliance with the US Government’s Orbital Debris Mitigation Standard Practices. Consistent with national policy, NASA notified the US State Department of the exception,’ a NASA spokesperson said.
When and where will Van Allen Probe A fall?
It is difficult to predict satellite reentries. The density of the upper atmosphere varies, and the latest forecast from the US Space Force indicated that Van Allen Probe A will re-enter the atmosphere around 01:45, Spanish peninsular time, tomorrow, March 12.
The Van Allen Probe A was launched in 2012 as part of a two-satellite mission to study the Earth’s radiation belts. These belts are an accumulation of electrically charged particles trapped by the Earth’s magnetic field and help protect our planet from cosmic radiation and solar storms. NASA ended the mission in 2019, when the satellites ran out of fuel.
The two Van Allen Probes were launched into elliptical orbits ranging from a few hundred kilometers above Earth to an apogee, or highest point, of more than 32,000 km. Due to the inclination of their orbits, Probe A is expected to end up falling in a strip around the equator located between 10 degrees north and south latitude.
Initially, NASA engineers expected the spacecraft to re-enter the atmosphere in 2034but more intense solar activity than expected caused the atmosphere to expand outward, increasing atmospheric drag on satellites and advancing their re-entry. The twin probe, Van Allen Probe Bshould not fall before 2030, with a similar risk for the population.
The two ships were built by Johns Hopkins University Applied Physics Laboratory. NASA has stated that the mission made several important discoveries, including ‘the first data showing the existence of a third radiation belt transient, which can form during periods of intense solar activity’.
It is not the first time that a NASA satellite re-enters the atmosphere without meeting risk standards. One of them, the Rossi X-ray Timing Explorer (RXTE), did so in 2018 with a probability of 1 in 1,000 of harming someone on the ground. There were no injuries. RXTE was launched in 1995, just four months before NASA issued its first rule on orbital debris mitigation and reentry risk management.