The Nivalis Powered Trailer Kit centers on an electric axle...rated at 50 kilowatts peak, capable of both propulsion assistance and regenerative braking. That axle draws on a 60-kilowatt-hour, 400-volt lithium-ion battery pack charged from three sources: the axle itself during braking and deceleration, a full-rooftop array of photovoltaic panels generating up to 3.7 kilowatts-peak, and a 32-amp, three-phase AC grid connection available during parking stops.

This approach is more akin to a plug-in hybrid: the truck may still be diesel-powered, but the electric assist from the trailer allows the truck to run more efficiently. Replacing diesel with kWh can save operators money while also reducing emissions. This incremental approach may be more accessible and less capital-intensive than replacing the truck itself.

Trailer Dynamics’s modular system offers three configurations ranging from 187 to 551 kilowatt-hours.... The M300 version [a 300-kWh battery] adds approximately four tonnes to the trailer.... Trailer Dynamics argues the weight penalty is largely academic in practice, because more than 90 percent of trailer movements are constrained by cargo volume before they approach legal weight limits.

Trailer Dynamics prices its system between €145,000 and €195,000 and targets a payback period of no more than five years. Nivalis targets five to six years at current costs.... Until someone publishes a full year of results from a trailer running in normal commercial rotation, fleet operators cannot answer the two questions that actually drives adoption: What does this cost, and when does it pay back?

In Texas, where Tesla is incorporated, the law requires companies to hold annual meetings no later than 13 months since the previous meeting. In Tesla’s case, that would be Sunday, July 13. Tesla has not announced a date for a meeting or filed any proxy statements — the documents that describe the annual meeting’s agenda, the candidates for the board and proposals to be voted on.

The meeting would normally provide shareholders an opportunity to speak directly to Tesla’s board and to Elon Musk, the chief executive, at a critical time for the company. Tesla sales have been plunging, and the stock price has fallen almost 40 percent from a peak in December.

In the early 20th century, when Henrietta Leavitt began studying photographs of distant stars at the Harvard College Observatory, astronomers had no idea how big the universe was....Leavitt, working as a poorly paid member of a team of mostly women [computers] who cataloged data for the scientists at the observatory, found a way to peer out into the great unknown and measure it.

Leavitt discovered the period-luminosity relationship for Cepheid variable stars. The relationship, now known as Leavitt's Law, is a crucial rung in the cosmic distance ladder, the methods for measuring the distance to stars, galaxies, and across the visible universe.

[Leavitt's Law] underpinned the research of other pioneering astronomers, including Edwin Hubble and Harlow Shapley, whose work in the years after World War I demolished long-held ideas about our solar system’s place in the cosmos. Leavitt’s Law has been used on the Hubble Telescope and the James Webb Space Telescope in making new calculations about the rate of expansion of the universe and the proximity of stars billions of light years from earth.

“She cracked into something that was not only impressive scientifically but shifted an entire paradigm of thinking....”

On Friday, Earth’s haunting silence will come to an end as NASA switches that communications channel back on, restoring humanity’s ability to say hello to its distant explorer.

Because of the direction in which it is flying out of the solar system, Voyager 2 can only receive commands from Earth via one antenna in the entire world. It’s called DSS 43 and it is in Canberra, Australia. It is part of the Deep Space Network, or DSN, which along with stations in California and Spain, is how NASA and allied space agencies stay in touch with the armada of robotic spacecraft exploring everything from the sun’s corona to the regions of the Kuiper belt beyond the orbit of Pluto. (Voyager 2’s twin, Voyager 1, is able to communicate with the other two stations.)

A round-trip communication with Voyager 2 takes about 35 hours — 17 hours and 35 minutes each way....

While Voyager 2 was able to call home on the Canberra site’s smaller dishes during the shutdown, none of them could send commands to the probe....

NASA ... did send one test message to the spacecraft at the end of October when the antenna was mostly reassembled.