"With the increased popularity and accessibility of expanded media platforms, the federal government's ability to publicize information has changed rapidly, but the total scope of federal public relations activities is largely unknown. A number of factors makes it difficult to quantify the resources the federal government devotes to public relations. These factors include the expanded use of web-based platforms, such as Facebook and Twitter, and the wide variety of activities that could be considered public relations, from publicizing health and safety bulletins to providing information on federal entitlements and benefits."
Keith's note: If you look at Table 3 (page 16), in FY 2014 NASA had 110 public relations employees whose aggregate salaries were $11,446,000 whereas DoD had 2,213 PR employees and an aggregate salaries of $176,644,000. If you look at Table 2 (page 11) between FY 2006 and FY 2015 NASA spent (on average) $3,415,000 on Advertising and public relations while DoD spent an average of $626,221,000. Of course, per Congressional legislation, NASA does not "advertise", right?