Don't cry UFO! just yet. Something big is taking off.

The world's largest airship, which will serve as a "stratellite", measures 235 feet long and will reach speeds of up to 80 mph. Designed to stay aloft for extended periods of time and run on an eco-friendly algae fuel, the Bullet 580 is designed to carry up to 2,000 lbs of payload 20,000 feet in the air.

While this lighter-than-air craft is the size of a 23 story building, it pales in comparison to the aerial leviathans of the past. The Hindenberg, for instance, ran a staggering 804 feet in length.

Future military applications are being considered for similar craft to aid in surveillance. Some say such ships are already being tested and can explain sightings of UFO's in recent times.

The Bullet 580 makes its maiden voyage later this year when it carries a NASA payload to measure moisture content of soil.

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