U.S. Army Space and Missile Defense Command (SMDC) is developing several prototype vehicles that could loiter near the edge of space for long periods to augment capabilities provided by satellites.


The command is planning to conduct flight demonstrations with two of the vehicles over the course of the next several months, according to Mike Lee, chief of the force enhancement branch in the space division at SMDC’s Space and Missile Defense Technical Center in Huntsville, Ala. Lee declined during a May 13 interview to discuss the amount of money being spent on the effort.


The aerial vehicles, which the Army calls “high altitude, long loiter” platforms, could help augment satellites for missions including communications, where they could be positioned over an area where satellites may be blocked, according to Rick Judy, a space systems analyst at SMDC.


The first flight demonstration is expected to take place in early June with the HiSentinel airship, which is being built by the Southwest Research Institute
of San Antonio
. The test will take place at Holloman Air Force Base in New Mexico. The vehicle is expected to loiter over a specific area for more than 24 hours,
Lee said.


HiSentinel features a 23-kilogram, 50-watt payload with a communications relay and a high-definition camera that takes still images
. The payload is carried by an inflatable airship that can launch in a flaccid state and does not require a hanger, he said.


The payload is recoverable, but the airship is not, Lee said. If the June flight demonstration goes well, SMDC could develop an operational version that could be ready in fall 2009 depending on demand and funding, he said.


The Army
also is working on a second lighter-than-air vehicle called the High Altitude Airship, which is built by Lockheed Martin MS2 Defense and Surveillance Systems in Akron, Ohio.


The High Altitude Airship program began under the Missile Defense Agency, which announced that it had canceled the effort when it sent its 2008 budget request to Congress in February 2007. The Army has since picked up the effort, and is changing the payload of a planned subscale flight demonstration in July 2009 from a missile defense sensor mission to a communications relay, Lee said.


The missile defense mission
still is planned for the operational version of the vehicle, which is envisioned as loitering over areas of interest for months at a time, Lee said. The subscale version of the vehicle in the July 2009 test likely will carry a payload weighing about 23 kilograms and will stay over a particular area for about 15 days at an altitude of more than 18 kilometers, he said.


The rigid nature of the High Altitude Airship, which is entirely recoverable, would force troops to launch the vehicle from a hanger near the battlefield in order to protect the structure from winds, Lee said. However, the rigid design also allows it to carry a payload that may ultimately be 10 to 20 times the size of what can be carried on a balloon like HiSentinel, he said.


also is exploring heavier than air vehicles, which lack the persistent dwell time over a particular area that comes with lighter than air concepts, but offer propulsion systems that can move them into a new area on their own power, Lee said.


These include the Zephyr, which is built by Qinetic of the United Kingdom. Zephyr demonstrated the ability
to operate at altitudes greater than 15 kilometers for 54 hours and 33 hours during two tests funded by the U.K. Ministry of Defense in July 2007.


SMDC is working with Qinetic in the hope
of extending the Zephyr’s
loiter time to around two weeks, Lee said. The biggest challenge in doing so is the vehicle’s power system, he said. Zephyr uses solar cells for power during the day, and relies on rechargeable batteries at night. SMDC is hoping to develop batteries that can hold their power after many charge cycles, Lee said.


SMDC is planning to demonstrate Zephyr
between July 15 and Aug. 15 at Yuma Proving Grounds in Arizona that would involve the vehicle loitering over a particular area for at least 15 days, Judy said.


The other heavier-than-air concept that SMDC is exploring is the Orion vehicle under development by Aurora Flight Sciences of Manassas, Va.,
which is envisioned as operating at an altitude of
around 20 kilometers for four days at a time with a payload weighing around 180 kilograms, Lee said.


SMDC has not yet picked a payload for the first flight test with the Orion vehicle, which could take place in 2010 if the command secures more funding for the work, Lee said.