With a landing that caused an unscheduled sonic boom, the X-37B touched down at NASA’s Kennedy Space Center on Sunday morning following a two-year space mission.

The unmanned US military space plane, which looks like a miniature space shuttle, touched down on Earth and the sound rattled the space centre’s neighbours, something which hasn’t happened in a long time.

It even caused some Twitter activity, with one woman tweeting that her house “shook” and her dog had “gone into a frenzy”.

Although no one is entirely sure what exactly the space plane was doing during its 718 days in orbit, all we have to go on is the US Air Force saying they “perform risk reduction, experimentation and concept-of-operations development for reusable space vehicle technologies”.

Here’s the landing:

The #X37B #OTV4 is the newest and most advanced re-entry spacecraft. Find out more about today’s landing here: https://t.co/GUGgOMQiYg pic.twitter.com/HfHHVnWhYc

— U.S. Air Force (@usairforce) May 7, 2017

Crazy stuff.

Sky News, however, has this:

The Secure World Foundation, a non-profit group that promotes the peaceful exploration of space, says the secrecy surrounding the X-37B suggests intelligence-related hardware is being tested or evaluated aboard the craft.

The space plane is a quarter of the size of NASA’s now-retired space shuttles, sitting at 29 feet long and with a wingspan of 15 feet. Cute, huh?

So why was the sonic boom such a surprise? Well, during the 30 years of NASA’s manned space shuttle programme, sonic booms were common, with landings at the Kennedy Space Center “preceded by a loud double boom,” reports Sky, but those landings ended about six years ago.

With this new, secret mission, officials refused to confirm the return date for the X-37B, so its arrival was not expected by residents hence all the Twitter commotion.

Imagine the inconvenience.

[source:sky]