First of all, Voyagers I and II have not reached the edge of the edge of the Universe, but they have reached the edge of our sun's Heliosphere (see image below, which shows the direction of our sun centered solar system as it moves through the interstellar medium, setting up a shock wave, left to right), thefinal boundary of the area under the influence of the Sun; the two major components to determining its edge are the heliospheric magnetic field and the solar wind from the Sun.
Although Voyager I crossed the heliopause first, Voyager II offers new opportunities. It carries an operating plasma science detector, whereas its predecessor's stopped working years ago.
Once the heliosphere is well and truly behind Voyager 2, it will be able to tell scientists about the flood of interstellar wind pushing against the heliopause and about the local bubble surrounding the heliosphere. It will register lots of galactic cosmic rays, the incredibly high-energy atoms of a whole range of elements that are careening across the universe at nearly the speed of light.
"Galactic cosmic rays act as tiny messengers of our local galactic neighborhood," said Georgia Denolfo, an astrophysicist at NASA. "We're able to actually look at the galaxy through the clouded lens of our heliosphere and now take a step outside with Voyager and for the first time contemplate the vistas of our local galactic neighborhood."
Within about 300 years, the Voyagers will reach the inner edge of the Oort Cloud, the giant spherical shell surrounding the Sun, planets and Kuiper Belt Objects, made of icy, comet-like objects. The Oort Cloud's icy bodies can be as large as mountains. Crossing that field will take somewhere in the realm of 30,000 years at their current speed.
When the Voyager probes eventually leave our solar system, they'll settle into a long slow orbit around our Milky Way galaxy like our solar system does, for millions, if not billions of years; humanity's first messengers into the vast space which surrounds our barred galactic host (rendering below).
JPL says Voyager I is expected to keep its current suite of science instruments on through 2021, while Voyager II is expected to keep its current suite of science instruments on through 2020.
The radioisotope thermoelectric generator on each spacecraft puts out 4 watts less each year. Because of this ongoing reduction in electrical power, the Voyager team must prioritize which instruments to keep on and which to turn off. Heaters and other spacecraft systems have also been turned off one by one as part of electrical power management.
The Voyager team has chosen to keep the instruments that are the most likely to send back key data about the heliosphere and interstellar space operating -- the fields and particles instruments. Engineers expect to begin turning off fields and particles science instruments one by one, starting in 2020 for Voyager II. Voyager II will have to start turning science instruments off sooner because it is currently operating one more instrument than Voyager I. Engineers expect each spacecraft to continue operating at least one science instrument until around 2025.
If science data isn't likely be collected after 2025, engineering data, like spacecraft health and systems status information, could continue to be returned for several more years. The two Voyager spacecraft could remain within range of the Deep Space Network through approximately 2036, depending on how much residual power the spacecraft will have to transmit a signal back to Earth.
As March 18th, 2020, Voyager I, the farthest of the two spacecraft, is some 13,800,000,000 miles from Earth and the round trip radio transmissions takes around 41 hours.
It is amazing to me that small pieces of man made engineering are still functioning and sending their data across those billions of miles of space and, despite the growing noise in that ever more feeble signal, we are still receiving.