5 August 2015
The small, planelike craft is known as the XS-1 program—short for 'eXperimental Spaceplane 1', and could blast off in 2019 on its first test mission.
It is hoped the craft could quickly launch small satellites that could defend against the growing threat of Russian and Chinese space weapons.
XS-1 could 'create a new paradigm for more routine, responsive and affordable space operations,' according to DARPA, the military research arm heading the project.
The XS-1 is an airplane-like vehicle that can fly to the edge of Earth's atmosphere and quickly boost small satellites into orbit, and then land, refuel, load up another satellite, and take off again within 24 hours.
'In an era of declining budgets and adversaries' evolving capabilities, quick, affordable, and routine access to space is increasingly critical for both national and economic security,' DARPA said in a press release.
However, it has remained tight lipped about the latest contract.
'The Boeing Co., Huntington Beach, California, has been awarded a $6,587,447 modification (P00004) to previously awarded HR0011-14-9-0005 (Other Transaction), for the Experimental Spaceplane (XS-1) program,' the announcement of the deal says.
'The additional tasks, identified as Phase IB, will continue the development of the XS-1 demonstration concept, substantiating identified core component technologies, mitigating risk, developing a Technology Maturation Plan (TMP), and performing several demonstration tasks.
'The addition of the XS-1 Phase IB tasks brings the total cumulative face value of the agreement from $10,000,000 to $16,587,447.'
Boeing must complete its XS-1 design and test its basic technologies before August 2016.
DARPA wants an XS-1 prototype to perform a realistic trial mission no later than 2019.
After that, the Pentagon could decide to build XS-1s for regular use.
'Developing a vehicle that launches small payloads more affordably is a priority for future U.S. Defense Department operations,' said Steve Johnston, director of Boeing's Phantom Works Advanced Space Exploration division when the oritinal funding was revealed.
'Boeing brings a combination of proven experience in developing launch systems and reusable space vehicles, along with unparalleled expertise in the development and fielding of highly operable and cost-effective transportation systems.'
The firm was initially given a $4 million preliminary design contract, to work on a reusable first stage launch vehicle capable of carrying and deploying an upper stage to launch small satellite payloads of 3,000 to 5,000 pounds (1,361 kg to 2,268 kg) into low-Earth orbit.
'Our design would allow the autonomous booster to carry the second stage and payload to high altitude and deploy them into space.
'The booster would then return to Earth, where it could be quickly prepared for the next flight by applying operation and maintenance principles similar to modern aircraft.' said Will Hampton, Boeing XS-1 program manager.
'Drawing on our other innovative technologies, Boeing intends to provide a concept that uses efficient, streamlined ground infrastructure and improves the turnaround time to relaunch this spacecraft for subsequent missions.'
DARPA wants the new spaceplane to be able to boost a two-ton satellite into space every day for 10 days straight for less than $5 million per flight.
The craft is set to be larger than the X-37B robotic spaceplanes that Boeing built for the Air Force.
Masten Space Systems and Northrop Grumman had also drawn up XS-1 blueprints. DARPA awarded the three firms $4 million apiece to do that preliminary design work.
Boeing also enlisted Washington State-based rocket start-up Blue Origin to help with the XS-1's motor, ans is believed to be planning to use Blue Origin's BE-4 to power the XS-1.
Capable of producing more than half a million pounds of thrust, the BE-4 is amonster of an engine.
Earlier this year the US Air Force's top secret X-37B space plane was been caught on camera by a team of amateur astronomers.
The unmanned plane launched atop a United Launch Alliance Atlas V on May 20 on its fourth mission, but most of the details about its flight remain classified.
The latest image, however, provides new insights into the spacecraft's activities and has fuelled speculation that X-37B may be a spy plane.
'It's in a lower orbit than normal … had us confused for a while, as I thought it would be the standard operating orbit,' tracker Greg Roberts told Space.com.
'The inclination is also lower than before.'
Roberts captured an image of the space plane in two-second–long exposures just a few weeks after launch.
Its inclination of 38 degrees is the lowest of the X-37B program, with the first mission flying at an inclination of 40 degrees.
It also features the lowest initial altitude of the four X-37B launches at 198 miles (318km). The previous low was OTV-2, at 205 miles.
The low-altitude flight profile may be a indication of test for a new propulsion technology.
'One thing that OTV-4 has in common with each of its predecessors is that its ground track nearly repeats after every 31 revolutions, which takes two days,' Toronto-based Ted Molczan told Space.com.
He added that this could be in support of a spy mission, to permit targets to be revisited frequently.
Other theories have for the spaceplane have ranged from it being a space bomber, to a clandestine probe on a mission to 'take out' spy satellites.
The mystery test vehicle — essentially a technology test bed — is designed to orbit the Earth and then land like one of Nasa's old shuttles.
While it's main mission payload is a mystery, Nasa last month revealed it has a materials experiment aboard, while the Planetary Society is tagging along with a solar-sail demo.
Called LightSail, it uses a propulsion system that uses the pressure of photons from the sun, a technique known as solar sailing.
Nine other CubeSat nanosatellites are also taking a piggyback ride into orbit.
The space plane - one of two of the same design - is operated robotically, without anyone on board, and is reusable.
It is 29ft long — about one-fourth the size of a Nasa shuttle. The longest X-37B flight lasted about 675 days; touchdown was last October.
There's no official word on exactly how long this one will stay up, although report suggest it will return to Earth in mid-to-late 2016.
In an unprecedented disclosure, last month month the Department of Defense did reveal some details about the X-37B's main mission.
'[We] are investigating an experimental propulsion system on the X-37B on Mission 4,' Captain Chris Hoyler, an Air Force spokesman, told Space.com.
'The Air Force Rapid Capabilities Office will also host a number of advance materials onboard the X-37B for Nasa to study the durability of various materials in the space environment,' Hoyler added.
He added the vehicle's mission 'cannot be specified' but that it will enhance 'the development of the concept of operations for reusable space vehicles'.
Spaceflightnow.com revealed more details of the flight, which is described as a 'hall thruster electric propulsion test.'
It is intended to improve performance of the units onboard Advanced Extremely High Frequency (AEHF) military communications spacecraft, officials claim.
AEHF satellites' Hall thrusters are 4.5-kilowatt units that use electricity and xenon to produce thrust for moving satellites in space.
The benefit of using electric propulsion is that its xenon fuel weighs much less than traditional hydrazine.
This technology could help in the development of technologies to control satellites with better accuracy.
However, experts claim that refining an advanced manoeuvring thruster is probably just a small part of the vehicle's true mission set.
One leading secrecy expert previously told DailyMail.com that the drone is 'very likely' be used to test technologies that will increase spying capabilities of the US.
'The US government has a bottomless appetite for sensitive information,' said Steven Aftergood, a secrecy expert at the Federation of American Scientists.
'As powerful as our intelligence satellites may be, they also have their limitations - most notably the limitations imposed by their orbital parameters.
'It's conceivable that a spy plane would introduce new versatility into overhead reconnaissance.'
The X-37B space drone, otherwise known as the Orbital Test Vehicle, is blasted into orbit by a rocket. However, it lands using a runway like a normal aircraft.
The X-37B is too small to carry people onboard, but does have a cargo bay similar to that of a pickup truck, which is just large enough to carry a small satellite.
The X-program has bounced between several federal agencies, Nasa among them, since 1999.
The plane has been in space for a total of 674 days, far more than its two previous flights which lasted 225 and 469 days.
The program's first mission launched in April 2010 and landed in December that year.
The second space plane took off on March 2011 and came back to Earth in June 2012.
According to X-37B manufacturer Boeing, the space plane operates in low-earth orbit, between 110 (177km) and 500 miles (800km) above earth.
By comparison, the International Space Station orbits at about 220 miles (350km).