Scientists say images of craters taken by European and U.S. space probes show there likely once was a planet-wide system of underground lakes on Mars.

The data provide the first geological evidence for an ancient Martian groundwater system, said a study by researchers in Italy and the Netherlands published in the Journal of Geophysical Research.

However Jack Mustard, a professor of geological sciences at Brown University who was not part of the study, said he didn't see such evidence in the data. "But I am probably just a skeptical Martian," he said.

Different kind of killer whale found

For decades, there were tales of a mysterious killer whale that just didn't look like the others. Now scientists say they've seen it.

"This is the most different looking killer whale I've ever seen," said NOAA marine ecologist Robert Pitman, who was part of the team that spotted the orcas off Cape Horn. The team is waiting for DNA tests but think it may be a distinct species.

The whale's signature large white eye patch is barely noticeable. Their heads are a bit more rounded and their dorsal fins are narrower and pointed. They likely mostly eat fish, not marine mammals like seals, as other killer whales do, he said. He said they probably can't breed with other killer whales and are likely a new species. At 20 to 25 feet long, they are slightly smaller than most killer whales.

Michael McGowen, marine mammal curator at the Smithsonian, said calling it a new species without genetic data may be premature. Still, he said, "I think it's pretty remarkable that there are still many things out there in the ocean like a huge killer whale that we don't know about."