Tips for finding NASA data: 
https://data.nasa.gov/data    (NASA data set catalog)   
https://data.nasa.gov/developer   (API catalog)  

http://catalog.data.gov/dataset   (All U.S. government data)
http://catalog.data.gov/organization/nasa-gov  (All NASA data)

on each challenge page:
e.g.: https://2015.spaceappschallenge.org/challenge/space-station-telemetry-app/
look for contact email e.g.: [email protected]

Also, Google it!

Twitter: 
@spaceappssf
#spaceapps
#spaceappssf
Flickr:
https://www.flickr.com/search/?text=spaceappssf
https://www.flickr.com/groups/spaceapps