Goddard Scientist Looks to AI, Lensing to Find Masses of Free-Floating Planets Image credit: NASA/JPL-Caltech
cuttingedge • goddard’s emerging technologies
Volume 17 • Issue 4 • Summer 2021
This illustration shows a Jupiter-like planet alone in the dark of space, floating freely without a parent star. The planet survey, Microlensing Observations in Astrophysics, scanned the central bulge of our Milky Way galaxy using the microlensing technique CUμLUS seeks to employ.
Exoplanet hunters have found thousands of planets orbiting close to their host stars, but relatively few of these alien worlds follow more distant orbits – and even fewer float freely through the galaxy, not bound to any star. NASA’s Roman Space Telescope will discover many more planets by observing dense star fields to maximize the chances of detecting an intervening planet as it passes precisely in front of a distant star. These chance alignments cause background stars to brighten briefly. The planet’s gravity acts as a lens that magnifies light from the background star’s light. One drawback of this technique, called gravitational microlensing, is that the distance to the lensing planet is poorly known. Goddard scientist Dr. Richard K. Barry is working to exploit parallax effects to pin down these distances. PAGE 10
Parallax is the apparent shift in the position of a foreground object as seen by observers in slightly different locations. Our brains exploit the slightly different views of our eyes so we can see in 3D. Astronomers in the 19th century first measured distances to nearby stars using the same effect, measuring how their positions shifted relative to background stars in photographs taken when Earth was on opposite sides of its orbit. It works a little differently with microlensing. In this case, two well-separated observers, each equipped with a precise clock, may observe the same microlensing event. The time delay between the two detections allows scientists to determine the distance to the lensing object. Barry is developing a concept called the CUbesat Continued on page 11
www.nasa.gov/gsfctechnology
