ADSL on its last legs in South Africa

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  By   Daniel Puchert Partially state-owned telecommunications company Telkom announced in its financial results for the year ending 31 March 2025 that its ADSL subscribers had more than halved to under 30,000. According to the company’s operational data, ADSL lines decreased from 64,959 in March 2024 to 29,770. This 54.2% decline highlights that the legacy broadband technology is slowly approaching the end of the road. Telkom’s ADSL business peaked at the end of March 2016 with 1.01 million subscribers — two years after fibre upstart Vumatel  broke ground in Parkhurst . What followed was a sharp decline in Telkom ADSL subscribers. Customers connected to its copper networks decreased by more than 500,000 over the next four years. This was partly driven by Telkom itself, which began actively switching off its copper network in some neighbourhoods. If it did not have fibre in the area, it would offer a “fixed line lookalike” wireless service that ran over its cellular ...
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In the Emptiness of Space 14 Billion Miles Away, Voyager I Detects “Hum” From Plasma Waves

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By CORNELL UNIVERSITY MAY 10, 2021

NASA’s Voyager 1 Spacecraft Entering Interstellar Space

This artist’s concept depicts NASA’s Voyager 1 spacecraft entering interstellar space, or the space between stars. Interstellar space is dominated by the plasma, or ionized gas, that was ejected by the death of nearby giant stars millions of years ago. The environment inside our solar bubble is dominated by the plasma exhausted by our sun, known as the solar wind. The interstellar plasma is shown with an orange glow similar to the color seen in visible-light images from NASA’s Hubble Space Telescope that show stars in the Orion nebula traveling through interstellar space. Credit: NASA/JPL-Caltech

Voyager 1 — one of two sibling NASA spacecraft launched 44 years ago and now the most distant human-made object in space — still works and zooms toward infinity.

The craft has long since zipped past the edge of the solar system through the heliopause — the solar system’s border with interstellar space — into the interstellar medium. Now, its instruments have detected the constant drone of interstellar gas (plasma waves), according to Cornell University-led research published in Nature Astronomy.

Examining data slowly sent back from more than 14 billion miles away, Stella Koch Ocker, a Cornell doctoral student in astronomy, has uncovered the emission. “It’s very faint and monotone, because it is in a narrow frequency bandwidth,” Ocker said. “We’re detecting the faint, persistent hum of interstellar gas.”

This work allows scientists to understand how the interstellar medium interacts with the solar wind, Ocker said, and how the protective bubble of the solar system’s heliosphere is shaped and modified by the interstellar environment.

NASA's Voyager Spacecraft

This artist’s concept shows NASA’s Voyager spacecraft against a field of stars in the darkness of space. The two Voyager spacecraft are traveling farther and farther away from Earth, on a journey to interstellar space, and will eventually circle around the center of the Milky Way galaxy. Credit: NASA/JPL-Caltech

Launched in September 1977, the Voyager 1 spacecraft flew by Jupiter in 1979 and then Saturn in late 1980. Traveling at about 38,000 mph, Voyager 1 crossed the heliopause in August 2012.

After entering interstellar space, the spacecraft’s Plasma Wave System detected perturbations in the gas. But, in between those eruptions — caused by our own roiling sun — researchers have uncovered a steady, persistent signature produced by the tenuous near-vacuum of space.

“The interstellar medium is like a quiet or gentle rain,” said senior author James Cordes, the George Feldstein Professor of Astronomy. “In the case of a solar outburst, it’s like detecting a lightning burst in a thunderstorm and then it’s back to a gentle rain.”

Voyager Mission Timeline

Voyager Mission Timeline. Credit: NASA/JPL-Caltech

Ocker believes there is more low-level activity in the interstellar gas than scientists had previously thought, which allows researchers to track the spatial distribution of plasma — that is, when it’s not being perturbed by solar flares.

Cornell research scientist Shami Chatterjee explained how continuous tracking of the density of interstellar space is important. “We’ve never had a chance to evaluate it. Now we know we don’t need a fortuitous event related to the sun to measure interstellar plasma,” Chatterjee said. “Regardless of what the sun is doing, Voyager is sending back detail. The craft is saying, ‘Here’s the density I’m swimming through right now. And here it is now. And here it is now. And here it is now.’ Voyager is quite distant and will be doing this continuously.”

JPL Mission Paths

NASA/JPL Mission Paths. Credit: NASA/JPL-Caltech

Voyager 1 left Earth carrying a Golden Record created by a committee chaired by the late Cornell professor Carl Sagan, as well as mid-1970s technology. To send a signal to Earth, it took 22 watts, according to NASA’s Jet Propulsion Laboratory. The craft has almost 70 kilobytes of computer memory and — at the beginning of the mission — a data rate of 21 kilobits per second.

Due to the 14-billion-mile distance, the communication rate has since slowed to 160-bits-per-second, or about half a 300-baud rate.

Reference: “Persistent plasma waves in interstellar space detected by Voyager 1” by Stella Koch Ocker, James M. Cordes, Shami Chatterjee, Donald A. Gurnett, William S. Kurth and Steven R. Spangler, 10 May 2021, Nature Astronomy.
DOI: 10.1038/s41550-021-01363-7

NASA, the Jet Propulsion Laboratory and the National Science Foundation supported the work. Cordes, Chatterjee and Ockler are members of Cornell’s Carl Sagan Institute.

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