The heliosphere, this vast bubble of solar influenceextends well beyond the planets of our system. The Voyager probes have revealed its complex and changing nature. Merav Opher, space physicist at Boston University, points out: “We now know how little we know about the heliosphere. It is much more complex and dynamic than we thought. »
This cosmic bubble fluctuates in response to 11-year cycles of solar activity, creating an ever-changing environment. Jamie Rankin, a space physicist at Princeton University, explains that these variations affect the entire heliosphere, potentially influencing our astronomical observations.
The boundaries of the heliosphere include:
- The terminal shock
- The heliosheath
- The heliopause
These regions mark the gradual transition into interstellar space, a journey that Voyager 1 completed in nearly eight years, testifying to the immensity of our cosmic neighborhood.
Unexpected discoveries in interstellar space
Beyond the heliopause, the Voyager probes entered a radically different environment. L'interstellar space is home to galactic cosmic rays, ancient stardust and other mysterious components. Sarah Spitzer of the Weizmann Institute of Science compares our situation to “goldfish trying to measure their fishbowl from the inside”.
Voyager observations revealed surprising phenomena, such as the multiple crossing of the terminal shock by a probe, suggesting notable fluctuations in the heliosphere. These data raise more questions than they answer, stimulating scientific curiosity.
Here's a look at the key findings:
| Sin | Date of entry into interstellar space | Major discovery |
|---|---|---|
| Voyager 1 | August 2012 | First direct measurement of the interstellar medium |
| Voyager 2 | November 2018 | Confirmation of Voyager 1 sightings in a different region |
The future of interstellar exploration
Although the Voyagers near the end of their mission, their legacy inspires new initiatives. There sonde New Horizonsfamous for its flyby of Pluto, continues its route towards the heliopause. Scientists hope that its instruments will still be working when it reaches this cosmic frontier in about ten years.
Ambitious projects like Interstellar Probe are also under study. This mission would be specifically designed to study the far reaches of the heliosphere and beyond, using cutting-edge instruments to analyze interstellar plasma and magnetic fields.
David McComas, principal investigator of the Interstellar Boundary Analyzer (IBEX) mission, works on IMAP (Interstellar Mapping and Acceleration Probe), described as an “IBEX on steroids.” This new mission promises more precise observations and additional measurements, including the analysis of interstellar dust grains.
Exploring space beyond our solar system remains a major technological and scientific challenge. Each new data collected by the Voyager probes is valuable, providing unique insight into a largely unexplored area of our galaxy. As Merav Opher points out, “Extending the Voyager mission as much as possible is invaluable. » These robotic pioneers continue to expand our understanding of the universe, reminding us that the greatest discoveries are often those that await us beyond known boundaries.
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