During the Earth observations, the spacecraft's spectrometers were able to detect the signatures of the Earth's water, ozone, methane, oxygen, carbon dioxide an

During the Earth observations, the spacecraft's spectrometers were able to detect the signatures of the Earth's water, ozone, methane, oxygen, carbon dioxide and possibly vegetation. I'm sorry but I don't get how they detected life on Earth. I can accept/imagine a few ways for tracing various chemicals/elements on a planet's surface and atmosphere from space but how can one detect life? Not only that but the reporter says "and possibly vegetation". So their results aren't conclusive?