Nasa has announced opportunities to test emerging technologies during flights on an airplane that simulates the weightless conditions of space.

The technologies should have potential use in future Nasa projects, support future exploration systems, or improve air and space vehicle capabilities.

Nasa's Facilitated Access to the Space Environment for Technology, or FAST, programme helps emerging technologies mature through testing in a reduced gravity environment. In order to prepare technologies for space applications it is important to demonstrate that they work in a zero-gravity environment.

This unique testing environment is provided by an aircraft flying repeated parabolic, or bowl-shaped, flight paths that create brief periods of zero gravity. The aircraft also can simulate reduced gravity levels similar to those on the surface of the moon or Mars.

Testing opportunities are being offered to US federal, state and local government entities. Private US organisations, including commercial firms, non-profits and academic institutions also are eligible. Through a partnership agreement, Nasa will provide free flight time for the tests, while project teams will be responsible for all other expenses.

Proposals are due by April 19. Technology demonstration flights will occur in September from Ellington Field in Houston. Nasa expects to select approximately 15 to 20 projects for the test flights.

Last September, the FAST programme provided reduced-gravity testing opportunities for 19 technology projects conducted by private businesses, government laboratories and universities.

Nasa's Innovative Partnerships Program at Nasa Headquarters in Washington manages the programme.

The Reduced Gravity Office at Nasa's Johnson Space Centre in Houston provides test management for the flights. Nasa's Glenn Research Centre in Cleveland is providing technical and administrative assistance to the FAST programme.