The search for biosignatures in the atmospheres of distant exoplanets is extremely difficult and time-consuming work. The telescopes that can potentially take the measurements required are few and more will come only slowly. And for the current and next generation of observatories, staring at a single exoplanet long enough to get a measurement of the …
Continue reading "A New Way to Find Signals of Habitable Exoplanets?"
It's tempting to look for habitable planets around red dwarf stars, which put out far less luminosity and so are less blinding. But is it wise? That question has been near the top of the list for many exoplanet scientists, especially those involved in the search for habitable worlds. Red dwarfs are plentiful (about three-quarters …
Continue reading "Red Dwarf Stars and the Planets Around Them"
Along the edge of an inlet on a tiny Japanese island can be found– side by side – striking examples of conditions on Earth some 2.4 billion years ago, then 1.4 billion years ago and then the Philippine Sea of today. First is a small channel with iron red, steaming and largely oxygen-free water – …
Continue reading "2.5 Billion Years of Earth History in 100 Square Feet"
A version of this article first appeared in Astrobiology Magazine, http://www.astrobio.net. Life on early Earth seems to have begun with a paradox: while life needs water as a solvent, the essential chemical backbones of early life-forming molecules fall apart in water. Our universal solvent, it turns out, can be extremely corrosive. Some have pointed to …
More than a half century ago, Stanley Miller and Harold Urey famously put water and gases believed to make up the atmosphere of early Earth into a flask with water, sparked the mix with an electric charge, and produced amino acids and other chemical building blocks of life. The experiment was hailed as a ground-breaking …
Continue reading "Messy Chemistry: A New Way to Approach the Origins of Life"
As the Cassini mission embarks on its final dive this Friday into Saturn, it will continue taking photos all the way down (or as far as it remains operations.) We've grown accustomed to seeing remarkable images for the mission and the planet, but clearly the show is not over, and perhaps far from it. …
Continue reading "Cassini Nearing the End, Still Working Hard"
Reading about some of the views coming from the man recently nominated to become NASA's Administrator, Rep. James Bridenstine of Oklahoma, I heard the sound of a door closing. Other doors will surely be opened if he is confirmed by the Senate, but that shutting door happens to be to the gateway to a realm …
Continue reading "Is That the Foundation of NASA I Feel Shifting?"
The triumphant Cassini mission to Saturn will be coming to an end on September 15, when the spacecraft dives into the planet. Running out of fuel, NASA chose to end the mission that way rather than run the risk of having the vehicle wander and ultimately land on Europa or Enceladus, potentially contaminating two …
White dwarf stars, the remnant cores of low-mass stars that have exhausted all their nuclear fuel, are among the most dense objects in the sky. Their mass is comparable to that of the sun, while their volume is comparable to that of Earth. Very roughly, this means the average density of matter in a …
Continue reading "Of White Dwarfs, "Zombie" Stars and Supernovae Explosions"
Asteroid, we've long been told, started tiny in our protoplanetary disk and only very gradually became more massive through a process of accretion. They collected dust from the gas cloud that surrounded our new star, and then grew larger through collisions with other growing asteroids. But in recent years, a new school of thought …
Continue reading "Primordial Asteroids, And The Stories They Are Telling"
Many Worlds 