Gretchen is an astro-geologist who studies craters. Her studies at university started in psychology, but one elective unit changed all that.

Gretchen has moved from the US, to the UK, eventually finding her way to Australia, where she has worked on projects like the Desert Fireball Network, which watches the sky and lets the team know when a new asteroid has landed on Earth.

She’s gone on expeditions to Antarctica to pick up meteorites, can analyse rocks that made the journey from Mars all the way to Earth, and even has an asteroid named after her.

Counting craters helps astro-geologists to understand the surface ages of planets. Older maps of craters on planets were painstakingly counted by hand. For Mars, it took over six years to identify 385,000 craters that were 1 kilometre wide.

As technology has improved, so has that ability to count. Using Pawsey’s supercomputer, Gretchen’s team analysed vast datasets of high-resolution images from Mars missions. Through machine learning, they automated crater detection, identifying more than 90 million impact craters in just 24 hours – a task that would have taken years manually. 

This work informed the world’s largest Mars crater database, enabling researchers to determine the age of surface features with unprecedented accuracy. It also supported major discoveries, including tracing the origin of the 'Black Beauty' meteorite back to a specific crater on Mars. 

00:00 Welcome & Big Questions About Mars
01:28 From Stargazing to Science: Gretchen’s Early Journey
05:38 From Psychology to Physics — Learning Through Failure
07:45 Meteorites, Asteroids, and Earth’s Place in Space
14:55 Falling in Love with Rocks: Meteorites, Geology, and Fieldwork
24:58 Pawsey, Data, and the Power of Supercomputing
33:16 Craters as Clocks: Dating Mars and the Moon
40:33 Mapping 94 Million Craters with Machine Learning
58:29 The Bigger Picture: Life, Planets, and What Comes Next

Watch a talk Gretchen Benedix gave at Pawsey in 2020:
Decoding the Surface Age of Mars: https://youtu.be/smA3tkvscZw 

For over 25 years, Chari has been instrumental in showcasing the power behind the waters that surround us, including discoveries in tsunami impacts and dense shelf water transport. 

Essentially oceanography studies the ocean, but there’s so much more to it, which Chari explains later.

Chari received the People's Choice Award at the Premier’s Scientist of the Year for 2025 for his contributions to Australian oceanography.

His work also helped discover locations of debris from the missing MH370 flight back in 2014, which we talk about as well.

Using oceanic drift modelling with Pawsey’s supercomputer, Chari was able to simulate two years’ worth of moving water. This gave plane debris locations along Madagascar, Mozambique and Tanzania.

Chari sees what he does as if it’s a jigsaw puzzle, taking each piece – like supercomputing, fieldwork and satellite imagery – and putting it together to see the whole picture. Chari has documented a lot of what makes our waters different from the rest of the world.

He was one of the first users of iVEC, which was what Pawsey Supercomputing Research Centre was called until 2014.

His love for the ocean has taken him from his home in Sri Lanka to the United Kingdom, and now in Australia, studying the Indian Ocean and why it vastly differs from other oceans.

Chapters:

• 01:34 - Discovering Oceanography
• 02:23 - Early Life in Sri Lanka
• 09:35 - From Sri Lanka to the UK
• 14:59 - Starting a Career in Computing and HPC
• 17:32 - Arriving in Australia and the Birth of MATLAB
• 20:58 - Supercomputers Transforming Ocean Science
• 27:55 - Global Data Collection and Observing Systems
• 36:04 - Major Scientific Breakthroughs
• 41:55 - The MH370 Search
• 46:52 - Future of Ocean Science & Climate Modelling

Watch our interview with Charitha Pattiaratchi from 2019: Finding MH370 using oceanographic modelling

Watch the video of this episode.
 

Click here to view the episode transcript.

This series is all about finding out the real-world impact that comes from using this large-scale computing.

We talk to researchers and scientists across Australia on how they have used HPC to discover their breakthroughs.

With hundreds of projects going on at any one time, we've yet to tap into all of these incredible stories. Those hearts and minds we keep mentioning here at Pawsey.

We've been lucky enough to talk to some incredibly passionate, sharp, generous people about the work they have done, and continue to do.

We hope you get as much joy listening to these as we did when we got to talk to each one. There's a lot of stories to dig out, and we can't wait to share them with you.

Visit our website to learn more about Pawsey.