---
title: "The World’s Most Mysterious Space Drone Is Finally on Its Way Back to Earth"
description: "The X-37B is expected to return from what could be its longest-ever clandestine mission in space — potentially beating its third mission's 674-day record."
date: "2017-03-20"
modified: "2017-03-20"
authors:
  - name: "Christianna Reedy"
    link: "https://futurism.com/authors/christianna"
url: "https://futurism.com/the-worlds-most-mysterious-space-drone-is-finally-on-its-way-back-to-earth"
categories:
  - "Drones"
  - "Off-World"
  - "Robotics"
  - "Robots and Machines"
  - "Space"
tags:
  - "boeing"
  - "drone spacecraft"
  - "unmanned spacecraft"
  - "x-37b"
---

# The World’s Most Mysterious Space Drone Is Finally on Its Way Back to Earth

![](<https://futurism.com/wp-content/uploads/2017/03/US-Air-Force.jpg>)
*\<em\>Image: \<a href="http://www.space.com/36101-x-37b-military-space-plane-nears-record.html?utm_source=notification" target="\_blank"\>U.S. Air Force\</a\>\</em\>*

## Autonomous and Top Secret

[Already on its fourth orbital mission](<https://futurism.com/the-secret-air-force-space-drone-heads-back-into-orbit>), the United States Air Force's X-37B remains the world's most mysterious aircraft. Also called the X-37 Orbital Test Vehicle (OTV), the X-37B is expected to return from what could be its longest-ever clandestine mission in space — potentially beating its third mission's 674-day record.

That is, if it gets back to Earth after March 25. Of course, there isn't much we could say about it, as details about the X-37B's missions are highly classified. However, USAF spokeswoman, Captain AnnMarie Annicelli, did divulge a few crumbs of information in[ an interview with ](<http://www.space.com/36101-x-37b-military-space-plane-nears-record.html?utm_source=notification>)*[Space.com](<http://www.space.com/36101-x-37b-military-space-plane-nears-record.html?utm_source=notification>).*

"The landing date will be determined based on the completion of the program's on-orbit demonstrations and objectives for this mission," Annicelli said.

[Developed by Boeing](<http://www.boeing.com/resources/boeingdotcom/media/dubai2015/pdf/Backgrounders/Bkgd_SatBiz_Key_Programs_eng.pdf>), the X-37B is an unmanned, autonomous spacecraft designed for prolonged orbital missions. The X-37B is a product of combined projects by [NASA](<https://www.nasa.gov/>) and [DARPA](<http://www.darpa.mil/>) with Boeing dating back to 1999, when the aerospace company was asked to develop a reusable orbital vehicle. Currently, the Air Force has two of these in service.

## Long-Lasting Missions

The first X-37B mission, or OTV-1, lasted for 224 days (from April 22 to Dec. 3, 2010). OTV-2 managed to stay in space for more than a year (468 days), from March 5, 2011 until June 16, 2012. On its third, even longer orbital mission, the X-37B was launched on Dec. 11, 2012, and landed on Oct. 17, 2014, completing more than 670 days in space. Its current mission [began May 20, 2015](<http://www.ulalaunch.com/ula-successfully-launches-afspc5.aspx>).

While we don't know much about the nature of these missions, [Boeing's description of the X-37B](<http://www.boeing.com/resources/boeingdotcom/media/dubai2015/pdf/Backgrounders/Bkgd_SatBiz_Key_Programs_eng.pdf>) gives us an idea. This drone spacecraft has been used "to explore reusable space vehicle technologies in support of long-term space objectives."

The [USAF's 2015 X-37B fact sheet](<http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104539/x-37b-orbital-test-vehicle.aspx>) adds, "Technologies being tested in the program include advanced guidance, navigation and control, thermal-protection systems, avionics, high-temperature structures and seals, conformal reusable insulation, lightweight electromechanical flight systems, advanced propulsion systems, and autonomous orbital flight, re-entry, and landing."

This is especially relevant, as missions to Mars (and back to the Moon) are in the works.