Solar Orbiter will graze the Earth tonight

Solar Orbiter come back to visit us before starting its main scientific mission: to explore the Sun and its connection with the ” space weather “. Indeed, the probe will fly over the earth November 27, passing at 4:30 a.m. UTC (5:30 am Paris time) just 460 kilometers above North Africa and the Canary Islands. By way of comparison, the International space station currently orbit at about 420 kilometers altitude.

This maneuver is necessary to reduce theenergy of the probe and direct it towards its next passage closest to the Sun. During the flyover of our planet, Solar Orbiter will however have to cross two regions orbitals populated by space debris : the ring of geostationary satellites, 36,000 kilometers away, and the area of ​​objects in orbit low, around 400 kilometers. Therefore, there is a weak risk of collision. The operations team Solar Orbiter is monitoring the situation very closely and will alter the path of the probe if it seems to be in danger.

Opportunity in Earth Sciences

This overview provides a unique opportunity to study the earth’s magnetic field. It is a subject of interest because the magnetic field is the interface between our atmosphere and the solar wind. These interactions are studied by two other missions of theESA : the four satellites of the mission Cluster, at an altitude of 60,000 km, and the three satellites of Swarm, 400 km. Several spacecraft are needed to break through “space-time ambiguity,” that is, the uncertainty as to whether a change has taken place because a probe has moved from one region to another with different conditions (a change in space) or fly over an area with changing conditions (a change in time). The overview of Solar Orbiter will provide even more data points from which to reconstruct the state and behavior of the earth’s magnetic field.

Cruise phase completed

This overview marks an important step for the probe. Of its launch in February 2020 to July of the same year, Solar Orbiter was in its commissioning phase, during which scientists and engineers tested the probe and its instruments. Since July 2020, Solar Orbiter is in the cruising phase. Meanwhile, the instruments in situ have taken measurements of solar wind and other conditions around the probe, while remote sensing instruments designed to look at the Sun were in their extended calibration and characterization mode.

Although Solar Orbiter is not yet in full scientific mode, a lot of scientific data has been produced. Daniel Müller, project scientist Solar Orbiter, explains that an upgrade of the ESA ground station network allowed the probe to send more data back to Earth than expected, and scientists on the mission were quick to take advantage: more than fifty articles detailing the scientific results of the cruise phase of Solar Orbiter must be published in December by the journal Astronomy & Astrophysics.

Closer to the Sun

The first perihelion of Solar Orbiter took place in June 2020, 77 million kilometers from the Sun. In March 2022, the probe will make its second pass as close as possible to our star, this time less than 50 million kilometers. ” It will be a third of the distance between the Sun and the Earth, explains Daniel Müller. So, compared to all high images resolution that we have already obtained, everything will now be enlarged by about a factor of two “. This includes new views of ‘ campfire »Enigmatic that Solar Orbiter observed during his first perihelion.

Solar Orbiter do not approach so close to the sun that the probe Parker Solar Probe of the Nasa, but it is voluntary: it not only allows Solar Orbiter to measure what is happening in the solar wind, but also to carry telescopes that can look at the Sun without being destroyeds by the heat. The two data sets can then be compared to relate the activity on the Sun’s surface to the weather report spatial around the probe.

Observation challenge

In the moments preceding the passage closer to Earth, observers at Canary Islands and in North Africa will be able to briefly see the probe streaking in the sky. It will move at about 0.3 degrees per second, which is just over half the apparent diameter of the Moon each second. For most observers, it will be too dim to be spotted at theeye naked and too fast for telescopes to follow. Binoculars should therefore offer the best chance of seeing it.

When Solar Orbiter will emerge from the shadow of the Earth, it will be on its way to its rendezvous with the Sun and the solar polar regions never before seen. The scientific phase of this ambitious mission will have started.