We are not talking about Richard Hoagland interpretaion of the Brookings report, we are talking about the page 215 of the Brookings Report which among other things states:
artifacts left at some point in time by these life forms might possibly be discovered through our space activities on the Moon, Mars, or Venus.
Read for yourself:
http://www.enterprisemission.com/images/brook-7.gif

This report was written from NASA specialists.