Roger Fu and Sarah Steele featured in Harvard Gazette article.

Evidence suggests Mars could very well have been teeming with life billions of years ago. Now cold, dry, and stripped of what was once a potentially protective magnetic field, the Red Planet is a kind of forensic scene for scientists investigating whether Mars was indeed once habitable and, if so, when.

The “when” question in particular has driven researchers in Harvard’s Paleomagnetics Lab in the Department of Earth and Planetary Sciences. A new paper in Nature Communications makes their most compelling case to date that Mars’ life-enabling magnetic field could have survived until about 3.9 billion years ago, compared with previous estimates of 4.1 billion years — so hundreds of millions of years more recently.