I am planning to do a data mining project on Kepler dataset but I am not sure whom to seek advice from. Could you please let me know if there is a NASA Stack Exchange or similar site?
There is a proposal for this in Area51 as space exploration. You can follow that. Right now it is commitment phase.
Here is the link to all the Stack Exchange sites. You can check if your question belongs to any of those by checking the description and faq there.
If your question involves computer programming code, you can ask it at http://stackoverflow.com.
If your question does not involve code, but you have a conceptual question about how you might design a computer program to perform the data analysis, you can ask it at http://programmers.stackexchange.com.
Review the FAQ for each site (there's a link at the top of the page) before asking a question there. It explains what's considered on-topic for each site, and how to structure your questions so that they will be acceptable to each community. Write you questions clearly, with enough detail to make them answerable. Be prepared to demonstrate prior research, and to respond to questions about your post in the comments section below it.