In January another commercial firm, Virgin Orbit, used its 30-ton LauncherOne orbital launch rocket to put seven small satellites into orbit for several customers, including the U.S. Department of Defense and NASA. This was the fourth of five tests of LauncherOne delivering small satellites for customers. The first use in 2020 failed but the three in 2021 and the recent one was a success. LauncherOne is carried by a modified B-747 airliner to an altitude of 11 kilometers (35.000 feet) and then released. LauncherOne can put a 500 kg (1,100 pound) payload into a 230-kilometer LEO (Low Earth Orbit) or a 300 kg (660 pound) payload into a 500-kilometer SSO (Sun-synchronous orbit). Each LauncherOne mission costs about $12 million, which includes the use of the transport aircraft. It cost less than a billion dollars to develop LauncherOne. Work began in 2007 and fourteen years later the first successful launch occurred, after only one failure. Putting satellites into the higher SSO is useful for payloads that are meant for longer missions to asteroids or other planets, like Mars or Venus.
An even more ambitious version of LauncherOne transporter is under development by a New Zealand firm that has developed the jet powered Aurora UAV (Unmanned Aerial Vehicle) that can fly to an altitude of about 31 kilometers and then launch a rocket carrying small satellites into LEO. The MKI Aurora was built and flight tested in 2018. The larger MKII Aurora was then built and flight-tested four times in 2021. MKII can carry a larger expendable rocket-propelled satellite delivery vehicle that can put up to 100 kg (220 pounds) of satellites into LEO. The larger MKIII Aurora is being built to carry out regular flights, several times a day, delivering 250 kg (550 pounds) of small satellites into LEO at less cost than LauncherOne. While innovative and economical, Aurora and LauncherOne are not new ideas, just a better implementation of the original concept first introduced and demonstrated in the 1990s.
These are novel evolutions of earlier efforts that used the same concept to launch ASAT (anti-satellite) missiles from high-flying aircraft. ASAT missiles are not new and back in the 1980s the U.S. developed and tested both ASAT missiles (ASM-135) and air-launched satellite launcher rockets (the Pegasus). Back then the U.S. Air Force developed the ASM-135 for knocking down LEO satellites by using a 1.2 ton-missile launched from a high-flying jet fighter. This was done in response to news that Russia was developing a similar system. The Russian system relied on killsats and was never that effective. A successful test of ASM-135 was conducted in 1985, but the program was shut down three years later because the Air Force preferred to spend the money elsewhere.
A little later, in the 1990s, a civilian firm (Orbital ATK) developed, tested and built Pegasus air-launched, from a B-52 or modified large airliner, three-stage solid fuel rockets for putting small (up to half a ton) satellites into LEO. The first version of Pegasus weighed 19 tons and the latest one 23 tons. Between 1990 and 2021 Pegasus carried out 40 successful launches. In other words, Pegasus is still in use and the Air Force has admitted that the ASM-135 could resume production and be even more reliable, effective and cheaper because of advances in missile and guidance tech since the 1980s.
More recent systems like Aurora take advantage of advances in UAV and small satellite technology. In the late 1990s several countries in the West (especially the U.S.) began developing very small satellites mainly because the technology had improved to the point where small was affordable and useful. The earliest of these ultrasmall satellites developed by the U.S. Department of Defense were called CubeSats. That is, their volume was no more than one liter (10x10cm or 4.1x4.1 inches) and weighed no more than 1.3 kg (three pounds). The military got the idea from the increasing use of commercial nanosatellites (which weigh no more than 6.8 kg/15 pounds). The U.S. military launched its first CubeSats in 2008 by piggybacking with a larger satellite that had unused space and weight in the payload nose cone.
It was quickly proven that CubeSats could be used for photo or electronic surveillance, or communications. The rapid advances in communications and sensor technology in the early 21st century made it possible to build a useful reconnaissance satellite weighing less and less. A tiny satellite like this includes solar panels to provide power. A British firm pioneered this technology in the 1990s and made it possible to get scientific satellites in orbit for a fraction of the usual price. Since 2008 nearly thousands of CubeSats (or similar designs) have been launched and the number is increasing each year. Most of the 173 micro-satellites used in the recent Soyuz and PSLV launches were based on the CubeSat design. That standardization also allowed for the establishment of standards for placing many micro-satellites in a rocket's final stage, another factor in keeping delivery costs down.
A satellite launcher like Pegasus, Aurora or LauncherOne can get satellites weighing up to 300 kg, or dozens of large cubesats into orbit on short notice and at much less cost than a rocket. That is a useful capability that is more important now that China is making an effort to destroy a large number of American satellites on short notice in any future conflict.