Getting recruited and accepted as a data scientist at NASA requires much more diverse and unique educational and cultural background as compared to other multinationals. A few of the key criteria which NASA looks up to in aspiring candidates are whether the candidate has served the nation in any other way or not, educational qualification & prowess is always preferred by NASA or any other US government agencies, and utmost focus on communication.
While the requisite technical and statistical knowledge is required as is the case with other organizations, these three criteria could potentially win the deal for candidates aspiring to get into NASA.
The same way as anywhere else + domain expertise should do the trick. Data scientists have to know stats, ML, programming, and data visualizations. Where you will stand out is if you have domain knowledge. Research their projects, team, and goals carefully. Polish up the resume and prepare for the interview. Sites such as Glassdoor, AceAI, Kaggle, Hackerrank, and Leetcode are all great prep sites.