Not a lot is known about the U.S. government’s X-37B space plane or its missions – but we do know it draws its power while in orbit from the sun via solar panels.
The Boeing X-37B Orbital Test Vehicle (OTV) is a reusable unmanned craft boosted into space by a rocket and designed to remain in orbit for extended periods before returning to Earth.
Reminiscent of the space shuttle design, the X-37B is far smaller – just 29 feet (8.9 m). Its loaded weight is 4.9 tonnes and the payload bay is just 2.1 × 1.2 m.
To reach space, an Aerojet storable liquid propellant (hydrazine – a highly toxic substance) rocket engine is used. Once in orbit, power for operations is supplied by gallium arsenide solar cells that charge a lithium-ion battery bank.
Gallium arsenide cells are often used in space applications, given their high efficiency and ability to generate electricity in extreme temperatures and in low light conditions. Gallium arsenide isn’t used in solar panels for the home solar power market (yet) as it is a rare substance and prohibitively expensive to use in mass-production applications.
The most recent launch of the X-37B occurred on March 5 last year – its mission was to test new (unspecified) space technologies. The craft returned to Earth on 16 June 2012 after having spent 469 days in space.
Last year, Boeing announced plans for another variant of the X-37 capable of carrying up to 6 astronauts. The X-37C will be approximately 165 to 180% the size the X-37B.
The X-37 projects have made some countries nervous due to their surrounding secrecy and the potential for the craft to carry space-launched weapons; triggering fears of a space arms-race. Similar fears were fuelled in the 1980’s when then-President Ronald Reagan launched the ill-fated Strategic Defense Initiative (SDI); more commonly known as “Star Wars”.
More on the Boeing X-37B Orbital Test Vehicle.
