October 6, 2011: America sees long (up to five years) endurance UAVs as salvation in the event of a space satellite apocalypse. The U.S. military is concerned about American dependence on space satellites, particularly the GPS birds. The U.S. Navy is particularly disturbed about this, because their warships depend on satellite communications while at sea. They can get by with the older wireless communications, but this form of transmission is very slow, and the navy has to move a lot more data these days in order to operate effectively.

The U.S. Air Force believes China is developing the ability to carry out a major attack on American military satellites (the "satellite apocalypse"). Their proposed solution is to take GPS out of orbit, and make it portable. High flying aircraft, UAVs or blimps would take over satellite communications, surveillance and navigation (GPS) chores, although for smaller areas. This would make GPS, and other satellite functions, more resilient to attack.

This where the navy and the long endurance UAVs come in. There are several models in development. They all are similar in concept. They are lightweight, use solar panels to drive the electric motors day and night and power the communications relay or sensors (cameras and such) and fly at high altitudes (20,000-30,000 meters, above the weather).

The American model is called Vulture. It's the one that can stay up for five years. Currently, a version capable of staying up three months is being readied for a test next year. That will be followed by the full size version, that will be tested with 12 months of continuous flight. Then will come multi-year flights, and entry into service (within five years). This version will have a payload of 450 kg (1,000 pounds) and be able to act as a communications and reconnaissance satellite substitute.

A British design, Zephyr, is smaller and successfully flew continuously for two weeks last year. This version of the Zephyr had a 22.5 meter (70 foot) wingspan, weighed 50.1 kg (111 pounds) and had a payload of about three kilograms (7 pounds). Three years ago, a slightly smaller version of Zephyr stayed up for 82 hours. Four years ago, Zephyr made its first long endurance flight. Several more, larger and larger, versions of this UAV are in the works, before it is ready for regular use by the troops.

Zephyr is by powered electric motors, using batteries recharged during the day by solar panels on the wings. During the day, the solar energy powers the aircraft's two propellers, and charges a battery. At night, the battery provides all the power needed to keep the aircraft aloft, although losing about a third of its altitude (which is normally about 18,000 meters/60,000 feet.) The ultimate goal is to have the Zephyr fly for months at a time, at high altitude (over 16,000 meters/50,000 feet, way above the weather). Built of lightweight materials, earlier Zephyrs weighed only 30 kg (66 pounds). The most likely job for Zephyr would be for communications relay, substituting for a communications satellite. There is growing demand for this, as commsats are expensive and take a long time to build and get in orbit.

To save weight, Zephyr has no landing gear. The current version is launched by having five men pick it up and walk it into the wind until its lifts off. It crash lands, but because of its light weight, there is not a lot of damage to be repaired.

Also called the HALE (High Altitude Long Endurance) aircraft, the Vulture, Zephyr and similar craft are basically powered gliders. Improvements in lightweight materials, solar panels and electronics have all made these new UAVs possible. Now, sensors (cameras and electronic detectors of all sorts) have become smaller, lighter and require less power. Thus while Zephyr is currently seen as a cost-effective communications satellite replacements (for troops beneath it, for several hundred kilometers in all directions), it could also take still pictures regularly, which would be very effective for a UAV circling around up there for months at a time.

This is part of a trend in which military satellites are getting priced out of the market by cheaper manned aircraft and UAV alternatives. Even small, quickly launched micro-satellites, cost ten times more, per hour over the battlefield, than do alternatives. These now include things like weather balloons carrying satellite grade communications or sensors.

While the air force is concerned about satellite security, the U.S. Department of Defense has to confront the fact that it cannot afford sufficient satellites to meet the growing demand for communications satellites. The commsats cost at least $250 million each, and even the much touted micro-sats still cost about ten percent of that.

The air force believes that it has the answer, by using alternatives like weather balloons equipped with satellite commo or intel gear. The high altitude "satellite replacement" balloons are based on existing weather balloon designs, but carrying communications, surveillance or GPS gear instead of weather sensors. As long as you can pick up and broadcast the same kind of signals satellites handle, you can put the equipment in a high altitude (up to 33 kilometers/100,000 feet) balloon, or even a bomber or tanker that spends hours circling the battlefield. This is particularly useful for communications. Much of the satellite communications needed by combat troops is with other people in the same general area. So the commsat replacement (a balloon or B-52) can do the job, passing off the long distance stuff to the real commsat.

 A balloon can cover troop needs for about a thousand kilometers in all directions. A B-52 or KC-135 tanker can deal with a smaller area, but is even cheaper than a $25,000 balloon, which is often only good for a few missions. Once launched, the balloon turns on its battery powered transponder when it has reached the proper altitude, maintaining its position like a hot air balloon, using computerized controls. It acts like a very low flying satellite until the battery runs out after 8-12 hours. Then the balloon deflates, a parachute brings it to earth in one piece, and a GPS beacon makes it possible for the equipment to be recovered for reuse.

One of the more useful aspects of balloons is that they are easy to carry, and can be inflated and launched by a Special Forces team out in the middle of nowhere. Special Forces recon teams often want to send back live video of whomever they are keeping an eye on. These balloon sats make that easier, because they can also carry satellite grade sensors (various types of night and day cameras).

 The major cause of more commsat use is live video being generated by the increasing number of vidcams on the battlefield. These vids are being exchanged by the units cooperating in an operation. Since that's all local, a "satellite substitute" (a balloon, or aircraft carrying the comm. gear) will work. Thus the interest in the UAVs that just fly circles high in the sky, acting as satellite substitutes. These substitutes cost less than ten percent, per hour in use, of what satellites cost.

 The satcomm shortage problem began during the 1990s, when the U.S. armed forces moved to satellite communications in a big way. This made sense, especially where troops often have to set up shop in out of the way places and need a reliable way to keep in touch with nearby forces on land and sea as well as bases and headquarters back in the United States. The major consumer of bandwidth is the live video. But without the GPS birds, the UAV video won't be necessary, because many targets won't be as vulnerable, and worth attacking. Although there is a backup (inertial guidance) system in smart bombs, the backup is much less accurate.