Measuring the gravity of climate change

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Don’t be turned off by the name of the publication! This article for SPIE Photonics is meant for anyone, and describes a very sophisticated experiment that connects my area of expertise (gravitational physics) to the most pressing issue of our time: climate change.

The GRACE to tackle climate change

A pair of orbiting spacecraft use laser technology developed for detecting gravitational waves to measure melting ice in Greenland

For SPIE Photonics:

Climate change is the largest existential threat facing humanity. Melting ice in polar regions and in mountains contributes to rising ocean levels worldwide; warming air disrupts jet streams and precipitation patterns, making severe storms more likely. Tracking these disruptions is essential for understanding how rapidly climate change is happening. However, Earth is big and many of the important fluctuations can be hard to measure without intensive local observations year-round.

But Earth-observation satellites present another extremely effective way to track climate change. Since 2018, a pair of spacecraft has been recording data that allow scientists to measure the melting of polar ice and the depletion of water tables during droughts. The satellites, together known as the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), track small fluctuations in Earth’s gravity as water moves from place to place. As its name suggests, the joint project between the US and Germany succeeds the original 2002-2017 GRACE mission. Both have proven so successful that researchers are now planning a third mission.

[Read the rest at SPIE Photonics]

Gravitational waves and climate change

Since early 2018, I’ve contributed multiple articles to Mercury, the membership magazine for the Astronomical Society of the Pacific (ASP). These articles are only available in full to members of ASP, but recently Mercury has put extensive previews for certain articles up on the website as enticement to join. One of those articles is my piece about the GRACE Follow-On mission, which is simultaneously a project that measures the effects of climate change and is a testbed for the upcoming LISA gravitational-wave observatory.

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! ]

The Gravity of Climate Change

For Mercury:

Orbiting spacecraft are an essential tool for mapping worlds in the Solar System, providing information about everything from landforms to magnetic fields. Repeated monitoring helps scientists measure variations in a planet as the seasons change. That’s particularly true for the planet we know best, and one that is experiencing the biggest variations of all the worlds in the Solar System: Earth.

The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission consists of twin space probes designed to measure Earth’s gravity to high resolution. That measurement is important for geology—seismic activity and other substantial shifts in Earth’s crust—but also for tracking shifts in water and ice around the world. Those variations help researchers measure the melting of polar ice, along with more subtle phenomena like the depletion of aquifers in western North America and India, for example.

In addition to its essential work measuring ice melting and climate change, GRACE-FO will test a vital component of the Laser Interferometer Space Antenna (LISA), the planned space-based gravitational wave observatory that will continue the work of LIGO and its Earth-based observatories.

[Read the rest of the preview in Mercury]

Listening to the sounds of the cosmos

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! ]

Last year, I went to a conference in Florida to hear — and in some cases meet — some of the leading thinkers in the study of gravitational waves. These waves are disturbances in the structure of spacetime itself, and could provide information about some exciting phenomena, if we can learn to detect them. The universe as heard in gravitational waves includes colliding black holes, white dwarfs locked in mutual orbits, exploding stars, and possibly chaotic disturbances from the very first instants after the Big Bang. This story marks one of my first big magazine articles, which I wrote for Smithsonian Air & Space magazine.

The Universe is Ringing

And astronomers are building observatories to listen to it

For Smithsonian Air & Space:

Think of it as a low hum, a rumble too deep to notice without special equipment. It permeates everything—from the emptiest spot in space to the densest cores of planets. Unlike sound, which requires air or some other material to carry it, this hum travels on the structure of space-time itself. It is the tremble caused by gravitational radiation, left over from the first moments after the Big Bang.

Gravitational waves were predicted in Albert Einstein’s 1916 theory of general relativity. Einstein postulated that the gravity of massive objects would bend or warp space-time and that their movements would send ripples through it, just as a ship moving through water creates a wake. Later observations supported his conception. [Read the rest at Air & Space….]