No Matter What It Takes

     UAVs Shoot Down Little Birds

     July 3, 2010: For the last decade, the U.S. Air Force has been developing and launching lightweight (under half a ton) reconnaissance satellites. This is the TacSat series. The first one was launched six years ago, while TacSat3 went up last year, and is now delivering data to combat commanders in Afghanistan.

     TacSat is not alone up there. There are a number of lightweight photo satellites in use. Two years before the 109 kg/240 pound TacSat 1 went up, Israel launched the 300 kg/660 pound Ofek-5. While TacSat 1 had only an infrared camera, regular camera, (both low rez) and a radio signals collection package, Ofek 5 a had one meter resolution digital camera, good enough to tell the difference between a tank and a car and spot a group of tanks assembling for attack. 

     The 400 kg/882 pound TacSat 3 had a wider array of sensors, including a hyperspectral (can detect a large range of light sources) imager, an Ocean Data Telemetry Microsatellite Link and the Space Avionics experiment. TacSat 3 sensors have a four meter resolution, but the ARTEMIS hyperspectral sensor can detect vehicles hidden in forests, as well as buried roadside bombs.

     The problem with these microsatellites is cost. The cheapest way to launch these small birds is via a solid fuel ICBM (preferably one that is being retired). Even there, the launch cost is going to be about $20 million per satellite. It's cheaper, and more convenient, to use larger UAVs to carry the sensors. The ten ton RQ-4 Global Hawk UAV can carry 1.2 tons of sensors, more than adequate for ARTEMIS. A RQ-4 costs $35 million, without payload (and normally over $120 million when equipped with satellite grade sensors.) The smaller, 4.7 ton, MQ-9 Reaper can carry a payload of 1.7 tons, and costs less than half as much as the RQ-4. 

     The Elusive X-37B

     October 15, 2010: After six months in orbit, the U.S. Air Force X-37B UOV (unmanned orbital vehicle) is proving elusive to amateur astronomers. This international collection of sky watchers have proved remarkably adept at spotting orbital objects in the past, including classified ones like the X-37B. One notable incident occurred two years ago, when a U.S. spy satellite fell out of orbit (apparently because of a failure in its maneuvering system). The amateur astronomers were able to track it. If this had not been an American reconnaissance satellite, there would have been no media attention to this, because 4-5 satellites a month fall back to earth. Since most of the planet is ocean, or otherwise uninhabited (humans tend to cluster together), the satellites tend to come down as a few fragments, rarely is anyone, or anything man-made, hit.

     Before the Internet became widely used a decade ago, you heard very little about all these injured or worn out space satellites raining down on the planet. But with the Internet, the many thousands of amateur astronomers could connect and compare notes. It was like assembling a huge jigsaw puzzle. Many sightings now formed a pattern, and a worldwide network of observers made visible the movements of hundreds of space satellites. These objects were always visible at night, sometimes to the naked eye, but unless you knew something about orbits and such, they could be difficult to keep track of. These days, a lot of the activity is posted and discussed at http://www.satobs.org/. But the X-37B has proved elusive, and has become a frustrating challenge to the amateur sky watchers. This is pleasing to American air force officials, who designed the X-37B to be elusive to terrestrial observation.

     The X-37B is a remotely controlled mini-Space Shuttle. The space vehicle, according to amateur astronomers (who like to watch spy satellites as well), appears to be going through some tests. The X-37B is believed to have a payload of about 227-300 kg (500-660 pounds), and capable of staying in orbit for 9 months. The payload bay is 2.1x1.4 meters (7x4 feet). When returned to earth, it will land by itself (after being ordered to use a specific landing area.) The X-37B weighs five tons, is nine meters (29 feet) long and has a wingspan of 4 meters (14 feet). The Space Shuttle is 56 meters long, weighs 120 tons and has a payload of 24 tons.

     The X-37B is a classified project, so not many additional details are available. It's been in development for eleven years, but work was slowed down for a while because of lack of money. A second X-37B is now being built, and is to be launched next year.

     What makes the X-37B so useful is that it is very maneuverable, contains some internal sensors (as well as communications gear), and can carry mini-satellites, or additional sensors, in the payload bay. Using a remotely controlled arm, the X-37B could refuel or repair other satellites. But X-37B is a classified project, with little confirmed information about its payload or mission (other than testing the system on its first mission). Future missions will involve intelligence work, and perhaps servicing existing spy satellites (which use up their fuel to change their orbits.) The X-37B is believed capable of serving as a platform for attacks on enemy satellites in wartime. 

     Improvising Around A Disaster

     September 1, 2010: The first of the U.S. Air Force’s AEHF (Advanced Extremely High Frequency) communications satellites was launched on August 14th. It achieved its initial orbit, but then it was discovered that its main maneuvering rocket, needed to get the six ton satellite into its permanent fixed, 36,000 kilometer, orbit, was not working. Efforts to get the main engine going failed. The engineers then went to work and found a way to use the lower thrust maneuvering rockets to still get the AEHF bird into position. But the alternate method will be slower, and take about nine months. That’s a small price to pay for a satellite that is supposed to last 14 years, once you get it in the right position. AEHFs will replace the older MILSTAR birds, providing more abundant and reliable (jam-resistant) communications. Two more AEHFs are under construction, with one going up next year and another in 2012. Several more will be ordered if the first three (costing about $2.2 billion each) perform as expected. The cost of the first three includes development costs, so additional ones will cost less than half as much.

     While the AEHF are mainly to facilitate communications between headquarters in the United States and troops abroad, they are also up there to deal with the huge increase in wireless devices the troops are using. For example, the number of military radios has nearly tripled, to over 900,000, in the last decade. There has also been a huge increase in data transmission capability (“bandwidth”) from 46 megabits (million bits) per second in late 2001, to nearly ten giga (billion) bits per second now. This is just for troops in CENTCOM (the Middle East and Afghanistan). That’s 200 times more data being pushed through three times as many “wireless devices” (radios). This doesn’t even count the many cell phones and laptops used by troops in the combat zone, which often use civilian bandwidth. But it hasn't been enough.

     The major consumer of all this new bandwidth 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. This huge growth in bandwidth began in 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. At the time of the 1991 Gulf War, there was enough satellite bandwidth in the Persian Gulf for about 1,300 simultaneous phone calls. Or, 12 megabits per second. But while the military has a lot more satellite capacity now (the exact amount is a secret), demand has increased even faster. UAV reconnaissance aircraft use enormous amounts of satellite capacity. The Global Hawk needed 500 megabits per second, and Predators about half as much. The major consumer of bandwidth is the live video.

     UAVs have other sensors as well, as do aircraft. A voice radio connection only takes about 240 bytes per second, and each of the multiple channels needed to control the UAVs use about the same. But it adds up, especially since the military wants high resolution video. At the moment, the U.S. has far more demand for satellite communications than it can support. As a result, not all the Predator and Global Hawk UAVs in combat zones have sufficient bandwidth to send their video back to the United States. Data compression and using lower resolution is often necessary, or using satellite substitutes (aircraft carrying transponders) to send the video to local users. The substitutes are becoming more common, simply because there is neither the money, nor the time, to get sufficient satellites into orbit.

     While the larger UAVs need satcomm to send video back to the United States, most of the bandwidth demand now is for local use. Tanks, helicopters and aircraft are all sending and receiving more vids, maps and data of all sorts. AEHF is needed to get essential material to higher headquarters as quickly as possible. The basic idea is to keep everyone connected, all the time. More radios, and other wireless devices are on the way, as well as more features any Internet user would recognize, all available while under fire. AEHF is an essential link in this data chain.