Twin Voyager Probes 25 Years In Flight

pbranes writes: "CNN has an article discussing the 25th anniversary of both of the Voyager spacecraft and what the next few years hold for the spacecraft. Scientists believe that they can maintain contact with the spacecraft for at least 20 more years, and they hope that the spacecraft passes the heliopause, the boundary for interstellar space, during this time." We've mentioned the long-term prospects of these probes before; it's not long until they may meet Termination Shock.

Comments

hope?

[Mt._Honkey]

Scientists believe that they can maintain contact with the spacecraft for at least 20 more years, and they hope that the spacecraft passes the heliopause, the boundary for interstellar space, during this time.

So they don't know if they will pass the heliopause during these 20 years? I assume that they know exactly where the probes are, so they must not know where the heliopause is. Does anybody know anything about this?

Re:hope?

[hubie]

They can only infer where the heliopause is. One way is by looking at things like MHD distrubances (i.e., magnetic shockwaves created by events on the Sun) that travel out and are reflected at the heliospere boundary (as the other poster mentioned); however, all they have at this point are computer models that suggest where it might be. The computer models over the last several decades have shown where the boundary will be, but the researchers have to keep revising the models every time the spacecraft passes the predicted boundary. If I recall correctly, the first prediction in the 60's (by Eugene Parker) expected the boundary somewhere about 5 AU or so, and the expected distance has been increasing ever since (I think it is up in the 100-150 AU range).

Some researchers have suggested that the heliopause might not be a well defined boundary and we might not notice passing through it for a while.

By the way, it is a very tough problem developing a detailed 3D model of the heliosphere when pretty much all your measurements are either inferred or taken mostly at 1 AU in the ecliptic plane (where Ulysses, the Pioneers, and the Voyagers are the exceptions). Even with the measurements the models are still very complicated and take quite a long time to run.