This story sounds a bit odd. I design AWS architectures for a living and whilst 250PB is a lot of data I see very little reason for large downloads that would incur these charges. The one reason to donwload the data would be to access on-premise compute resources, which would make little sense to do for organization doing research. AWS compute offering is super cost-effective and incredibly scalable if designed correctly. It would be interesting see more about their use case and the need to download so much data. For analytics, AWS supports all the major languages, ML notebooking, and more.
1) I found this case study for NASA that build this library (https://images.nasa.gov/) basesd on a architecture for delivering image content to the public. (https://aws.amazon.com/partners/success/nasa-image-library/)
This CDN implementation would incur cost with content getting stored at edge locations.
2) Open Data on AWS stored in S3 Object Store, which is are available in us-west-2
A collection of Earth science datasets maintained by NASA, including climate change projections and satellite images of the Earth's surface.
It would be interesting to dig into this one in detail and figure out how they have things configured....