"The administrator is unable to attend. Bill Gerstenmaier and Bob Cabana will be there representing NASA, among others," Powers said on Friday.
The conference, scheduled to take place November 18-19, will bring together key officials and veterans of the space industry.
On Thursday, Bridenstine met with Russian Ambassador to the United States Anatoly Antonov in Washington, DC to discuss US-Russia space cooperation.
Bridenstine visited Russia in early of October, where he praised the successful collaboration between Russia and the United States on the International Space Station (ISS) as a means to improve bilateral cooperation on earth science and share relevant information.
