OK, I've come across the original info from the journal, Nature Astronomy. Believe me, it was hard to find. There were so many articles from other sources that said the same thing - wall of fire. Two things bugged me - the first round of searches came up with light-weight posts, and they said pretty much the same thing.
Finally, I found the original science posts. It probably will come as no surprise that I did not find that verbiage in either the JPL or Nature Astronomy posts. I have some questions about where the probes are and what they are doing right now. Perhaps
Lila,
Kevin C,
therium, or anyone else will give it a look with me.
JPL (Jet Propulsion Laboratory that works with NASA) had a summary of the data.
https://voyager.jpl.nasa.gov/news/details.php?article_id=116
At a distance of about 11 billion miles (18 billion kilometers) from Earth - well beyond the orbit of Pluto - Voyager 2 had entered interstellar space, or the region between stars. Today, five new research papers in the journal Nature Astronomy describe what scientists observed during and since Voyager 2's historic crossing.
The new papers now confirm that Voyager 2 is not yet in undisturbed interstellar space: Like its twin, Voyager 1, Voyager 2 appears to be in a perturbed transitional region just beyond the heliosphere.
This is as close as I come to the wall of fire - perturbed transitional region. What I do not read specifically is if the probes still are moving forward or "like flies on a window pane".
If the heliosphere is like a ship sailing through interstellar space, it appears the hull is somewhat leaky. One of Voyager's particle instruments showed that a trickle of particles from inside the heliosphere is slipping through the boundary and into interstellar space. Voyager 1 exited close to the very "front" of the heliosphere, relative to the bubble's movement through space. Voyager 2, on the other hand, is located closer to the flank, and this region appears to be more porous than the region where Voyager 1 is located.
Cosmic ray measurements from Voyager 2 as it crossed into interstellar space https://www.nature.com/articles/s41550-019-0928-3
However, just beyond the heliopause Voyager 2 discovered a boundary layer, in which low-energy particles streamed outward along the magnetic field and cosmic ray intensities were only 90% of those further out.
Energetic charged particle measurements from Voyager 2 at the heliopause and beyond https://www.nature.com/articles/s41550-019-0927-4
Magnetic field and particle measurements made by Voyager 2 at and near the heliopause https://www.nature.com/articles/s41550-019-0920-y
The heliopause is a boundary that separates the heliosheath (which contains magnetic fields and plasmas that originate in the Sun) from the interstellar medium (which contains magnetic fields and particles of stellar/interstellar origin). Observations of the heliopause were first made by the particles and fields instruments on the Voyager 1 spacecraft, moving radially in the northern hemisphere, which crossed the heliopause on 25 August 2012 at a distance of 121.6 au. We show using observations of the magnetic field and energetic particles that Voyager 2 crossed the heliopause in the southern hemisphere on 5 November 2018 at a distance of ≈119.0 au. Voyager 2 observed a much thinner and simpler heliopause than Voyager 1 as well as stronger interstellar magnetic fields, and it discovered a ‘magnetic barrier’ in the heliosheath adjacent to the heliopause that strongly influences the entry of cosmic rays into the heliosphere. The magnetic field direction observed by Voyager 2 changed smoothly from the time of arrival at the magnetic barrier, through it, and onwards into the interstellar medium, with a small (a few degrees) or no change across the heliopause. These observations, together with the Voyager 1 observations and existing models, show that the magnetic barrier, the heliopause and the neighbouring very local interstellar medium form a complex interconnected dynamical system.
Are the probes still in the very local interstellar medium?
Plasma densities near and beyond the heliopause from the Voyager 1 and 2 plasma wave instruments https://www.nature.com/articles/s41550-019-0918-5
Voyager 2 plasma observations of the heliopause and interstellar medium https://www.nature.com/articles/s41550-019-0929-2
The solar wind blows outwards from the Sun and forms a bubble of solar material in the interstellar medium. The heliopause (HP) is the boundary that divides the hot tenuous solar wind plasma in the heliosheath from the colder, denser very local interstellar medium (VLISM). The Voyager 2 plasma experiment observed the HP crossing from the solar wind into the VLISM on 5 November 2018 at 119 au. Here we present the first measurements of plasma at and near the HP and in the VLISM. A plasma boundary region with a width of 1.5 au is observed before the HP. The plasma in the boundary region slows, heats up and is twice as dense as typical heliosheath plasma. A much thinner boundary layer begins about 0.06 au inside the HP where the radial speed decreases and the density and magnetic field increase. The HP transition occurs in less than one day. The VLISM is variable near the HP and hotter than expected. Voyager 2 observations show that the temperature is 30,000–50,000 K, whereas models and observations predicted a VLISM temperature of 15,000–30,000 K.
