NASA has developed probe-telescope SHIELDS, designed to study the heliosphere and detect particles that enter the Solar system from interstellar space. The first flight of a suborbital rocket with a telescope onboard is scheduled for April 19. The launch will take place from the White Sands missile range in New Mexico. The information is available on the official NASA website.
The heliosphere is a region of near-solar space in which the plasma of the solar wind — a stream of ionized atoms of the solar corona — moves in the magnetic field of the Sun at supersonic speed. Thanks to the heliosphere, all objects in the Solar System are protected from the negative effects of cosmic radiation coming from interstellar space.
During the first ten billion kilometers from the Sun, the solar wind speed is about one million kilometers per hour. Colliding with the interstellar medium in what scientists call the shock wave boundary, the solar wind slows down. Even further away is the heliopause — the outer boundary of the heliosphere, along which the pressure of the interstellar medium and the solar wind balance each other. Here the protective bubble of the Sun’s magnetic field ends, and interstellar space begins.
“This is really the farthest boundary that we can explore,” said Walt Harris, the principal investigator of the SHIELDS mission, a space physicist at the University of Arizona. — We still know very little about what lies beyond that border. Fortunately, we can be helped in this by the particles of interstellar matter that pass through this boundary and enter the Solar system.”
According to the project of the SHIELDS (Spatial Heterodyne Interferometric Emission Line Dynamics Spectrometer) mission, the probe is placed onboard a rocket that will reach an altitude of about 300 kilometers in a few minutes after launch. After that, the instrument will focus on the “nose” part of the heliosphere to catch the light from the incoming hydrogen atoms.
The solar system, enclosed in the heliosphere as in a magnetic bubble inflated by the Sun, rushes through space at a speed of 23 kilometers per second. Interstellar particles hit the “nose” of the heliosphere like rain on the windshield of a moving car.
SHIELDS will measure light from a special group of neutral hydrogen atoms from interstellar space. Charged particles flow around the heliopause, and neutral particles, with a balanced number of protons and electrons, cross the magnetic field lines, penetrating through the heliopause into the Solar System, but they are deflected. From these deviations, the instrument can reconstruct the trajectories of the particles to determine where they came from, and the SHIELDS spectrometer’s observations of the change in wavelengths will allow us to determine their velocities.
By analyzing these parameters, scientists hope to reconstruct the shape of this bubble and get the first data on the structure of interstellar space beyond it, since, according to physicists, the heliosphere should deform when it collides with the interstellar medium — shrink where the resistance is greater, and expand where it is less. For example, scientists believe that the Solar System is now passing through a rarefied section of space about 300 light-years long in the spiral arm of Orion of our Milky Way galaxy. Astronomers call this area the Local Bubble. It contains hundreds of stars, including the Sun. Calculations indicate that its density is about one-tenth that of the rest of the main disk of the Galaxy. The results of the SHIELDS telescope observations should confirm or refute these theoretical constructions.