To understand and define the boundaries of our heliosphere, SwRI researchers collaborated with other scientists to use existing numerical simulations to reveal the structure of the heliosphere and its interaction with the interstellar medium. Solar wind data and solar wind pressure forecasts provide important information for heliospheric models to help predict when the New Horizons spacecraft will encounter the heliospheric termination shock, on its way to joining the Voyager 1 and 2 spacecraft in interstellar space.
Image Credit: Courtesy of NASA/IBEX/Adler Planetarium/SwRI
Scientific Frontline: Extended "At a Glance" Summary: Solar Wind Forecasting and Heliosphere Boundaries
The Core Concept: Scientists are utilizing solar wind forecasting methods, combined with analytic and numerical models, to predict the dynamic plasma boundaries of the outer heliosphere. This research specifically aims to determine when the New Horizons spacecraft will intersect the termination shock.
Key Distinction/Mechanism: The heliosphere is a vast plasma bubble generated by the solar wind that shields the solar system from interstellar radiation. Its boundaries constantly expand during solar maximum and contract during solar minimum, meaning that a spacecraft could potentially cross the termination shock multiple times as the boundary fluctuates.
Major Frameworks/Components:
- Solar Wind Forecasting Methods: Predictive techniques used to model the long-term variations and outward flow of solar plasma.
- Analytic and Numerical Heliosphere Models: Mathematical and computational frameworks used to simulate the structure of the heliosphere, which is theorized to be either comet-like or croissant-shaped.
- Termination Shock: The inner boundary where the solar wind abruptly slows down as it begins to interact with interstellar material.
- Heliopause: The outermost plasma boundary where the outward pressure of the solar wind completely halts against the interstellar medium.
- Solar Cycle Dynamics: The fluctuating periods of solar maximum and solar minimum that dictate the physical expansion and contraction of the heliosphere.
Branch of Science: Heliophysics, Astrophysics, and Space Science.
Future Application: The forecasting models will prepare the New Horizons spacecraft to take critical measurements and transmit data upon reaching the termination shock, an event projected to occur between 2029 and 2040. These predictive frameworks will also guide the planning and execution of future interstellar space missions.
Why It Matters: Determining the exact position and behavior of the termination shock enhances our fundamental understanding of how the solar system interacts with the interstellar medium, and it reveals how the heliosphere effectively shields our planetary system from high-energy galactic radiation.
Southwest Research Institute (SwRI) scientists are using a solar wind forecasting method, combined with analytic and numerical heliosphere models, to determine where the first plasma boundary of the outer heliosphere lies as NASA’s New Horizons spacecraft hurtles toward this mysterious region of space.
The heliosphere, a vast bubble of plasma created by the solar wind flowing outward from the Sun, surrounds the entire solar system and shields it from much of the high-energy galactic radiation found in interstellar space. Scientists believe the heliosphere resembles a comet because the Sun moves through the interstellar medium, creating a rounded “nose” region and a trailing “tail.” Other models predict a croissant-shaped heliosphere.
SwRI researchers are studying the heliosphere’s dynamic outer boundaries, including the termination shock and the heliopause, where the solar wind slows and then abruptly stops as it interacts with interstellar material. These boundaries constantly expand and contract in response to changing solar conditions. During solar maximum, the “turbocharged” solar wind expands the heliosphere. During solar minimum, the ebbing solar wind allows the heliosphere to contract.
Two recent scientific papers explore how to accurately predict the location of the termination shock, particularly in the direction New Horizons is traveling.
After completing historic flybys of Pluto and the Kuiper Belt object Arrokoth, New Horizons continues deeper into the outer solar system on a trajectory toward the heliosphere’s forward region. It will reach the termination shock and later leave the solar system, making it only the third spacecraft to do so after Voyager 1 and Voyager 2. Scientists hope to determine when the spacecraft will encounter this plasma boundary surrounding the solar system.
“We want to understand when the spacecraft will reach the termination shock to prepare to take measurements and download data about this region,” said Dr. Jonathan Gasser, lead author of the two papers. “Based on our research, we predict that New Horizons will encounter the termination shock as early as 2029 or as late as 2040. And it is possible that it could cross the boundary more than once as the heliosphere continues to expand and contract.”
This research could improve our understanding of how the heliosphere interacts with interstellar space, helping future missions explore the boundaries between the solar system and the interstellar space beyond.
Published in journal:
- Advances in Space Research
- The Astrophysical Journal
Title:
- Predictions of New Horizons’ termination shock crossing
- Solar Wind Forecasting for Long-term Variations of the Global Heliosphere
Authors:
- Jonathan Gasser, Justyna M. Sokół, Heather A. Elliott, Maher A. Dayeh, Kelsi N. Singer, S. Alan Stern, Igor Baliukin, Sergey Korolkov, Pontus C. Brandt, Joel W. Parker, Andrew R. Poppe, Anne J. Verbiscer, and Merav Opher
- Jonathan Gasser, Justyna M. Sokół, Maher A. Dayeh, Heather A. Elliott, Kelsi N. Singer, and Merav Opher
Source/Credit: Southwest Research Institute
Edited by: Scientific Frontline
Reference Number: heli062226_01
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