Axios

Four companies — SpaceX, Blue Origin, United Launch Alliance (ULA) and Northrop Grumman — have submitted proposals to become 1 of 2 launch providers for the U.S. Air Force from 2022 to 2026.

Why it matters: Launching commercial and government payloads to orbit is a competitive business, and locking in billions of dollars in revenue from the Air Force would be a huge win for any of these companies.

Radioactive dust sent out by ancient supernovas has been found in Antarctica, according to a new study in the journal Physical Review Letters.

The big picture: Researchers behind the study suggest that our solar system is currently flying through a cloud of cosmic material thought to be shaped by supernovas.

Scientists can’t agree on the answer to a foundational question in physics — how fast the universe is expanding — and to some, the debate signifies that their understanding of the universe may be about to shift.

The big picture: Cosmologists have been debating the expansion rate of the universe — known as the Hubble Constant — for decades, but today’s controversy centers on two camps that disagree on just how fast our 13.8 billion-year-old universe is moving.