WHAT'S ON BOARD?

Hall ion-powered thruster

Hall thrusters are electric propulsion devices that create thrust by ionising and accelerating a noble gas. They offer better fuel economy and allow larger payloads and more on-orbit manoeuvring. This thruster is a modified version of those used on Advanced Extremely High Frequency military craft.

LightSail

The non-profit Planetary Society took advantage of the mission by hitching a ride, putting a small LightSail into Earth orbit. It carries four large, reflective sails that measure 32 square metres (344 square feet). Although too small to sail to the stars, the mirrored sails use the Sun’s energy to generate momentum. Photons within the Sun’s light push on the surface, lending a continuous thrust.

CubeSats

CubeSats are miniature research satellites, and as well as LightSail, X-37B deployed a further nine. Highly technical, they included a satellite researching the hosting of web servers on a CubeSat, one testing the on-orbit operation of a Micro-Cathode Arc Thruster and one demonstrating the use of the Globalstar constellation to control low-Earth orbit spacecraft.

NASA test equipment

A NASA experiment called Materials Exposure and Technology Innovation in Space exposed 100 different materials to the harsh environment of space. It is hoping to expand on the results gained by conducting a similar experiment on board the ISS, with some of the materials previously looked at being taken on board the space plane for testing.

A good dollop of mystery technology

As befits a mystery mission, there are bound to be other items on board the space plane, but official sources are not letting slip on further details. It is likely that whatever is on board will be tested for the effects of long-term exposure. The bonus of a spacecraft like this is that any objects that are sent up can be brought back down for further tests.