"This suggests to me that perhaps these events are the result of a design error in the fuel tanks or other systems that are rupturing after several years in space rather than something like a collision with a piece of debris," Weeden said.

In terms of orbital debris, this is likely not a catastrophic event, Weeden said. There are not that many sizable chunks of debris from the small satellites; however, this debris will be long-lived, as it starts at such a high altitude above Earth's atmosphere. By comparison, debris produced by China's anti-satellite test in 2007, when a 750-kg satellite was destroyed at an altitude of 865 km, is expected to remain in orbit for decades more.

So, it seems fragments of the Cosmos breakups will likely be with us for the remainder of the 21st century before finally tumbling into Earth's atmosphere.

Observations of supermassive black holes at the centers of galaxies point to a likely source of dark energy—the 'missing' 70% of the universe.

The measurements from ancient and dormant galaxies show black holes growing more than expected, aligning with a phenomenon predicted in Einstein's theory of gravity. The result potentially means nothing new has to be added to our picture of the universe to account for dark energy: black holes combined with Einstein's gravity are the source.

The conclusion was reached by a team of 17 researchers in nine countries, led by the University of Hawai'i and including Imperial College London and STFC RAL Space physicists. The work is published in two papers in the journals The Astrophysical Journal and The Astrophysical Journal Letters.

Study co-author Dr. Dave Clements, from the Department of Physics at Imperial, said, "This is a really surprising result. We started off looking at how black holes grow over time, and may have found the answer to one of the biggest problems in cosmology."

Study co-author Dr. Chris Pearson, from STFC RAL Space, said, "If the theory holds, then this is going to revolutionize the whole of cosmology, because at last we've got a solution for the origin of dark energy that's been perplexing cosmologists and theoretical physicists for more than 20 years."