NASA has issued a waiver for grantees allowing them to be reimbursed out of their grants for lodging above per diem up to the cost of the conference hotel.
For details, please see:
Please note that some organizations have written policies that do not allow their employees to charge more than the federal per diem rate for conference or other local area hotels, so please check with your organization about its policy.
Max Bernstein, SMD lead for research