November 19, 2022: The American X-37B space finally landed on November 12th after a record breaking 908 days in orbit. This was the sixth orbital mission for the X-37B and it began on May 17, 2020. The previous mission was 780 days and the ones before that 718, 675, 469, and 225.

Mission 6 was originally scheduled for late 2019, using the disposable Atlas 5 launch vehicle normally employed but probably on its way out. SpaceX is cheaper and has a growing list of successful landings including twelve successes in a row, including all ten in 2017. The SpaceX landing tests began in 2010 and the first orbital mission was launched in April 2010.

The X-37B was developed by NASA as the X-37A but in 2004 that project was turned over to DARPA (Defense Advanced Research Projects Agency). In 2006 the U.S. Air Force announced it was developing a larger X-37B and this replaced the DARPA X-37A project.

The X-37B is unmanned and operated by earth-based controllers. It does have automatic landing software that has been used several times without any problems. While the air force reports few details about the X-37B, it was difficult to hide the fact that mission 5 used a different launch vehicle; the SpaceX booster. This was important because the SpaceX rocket itself is reusable; its first stage returns to earth and lands upright for refurbishing and reuse. Air force officials noted that the SpaceX design is a fitting match for X-37B which was designed for multiple reuse and autonomous operation. How many times an individual X-37B can be used is unclear. There are two X-37B space planes so they are not putting the same one back into orbit soon after it returns. While one X-37B is in orbit the other one is being prepared for the next mission. This may include modifications so new equipment and capabilities can be used.

In effect, the X-37B is a remotely controlled mini-Space Shuttle that was inspired by the original manned Space Shuttle program which was so much more expensive than originally planned that it was given up as not worth the cost. The last shuttle mission was in 2011. It was cheaper just to send new satellites up although the U.S. Air Force has had its X-37B unmanned mini-space shuttle launched for the first time in 2010. The X-37B has shown it remain operational in orbit for (so far) over two years before returning. The air force won’t say exactly what it is doing up there.

The official endurance of the X-37B was originally about nine months (280 days). The real endurance appears to be 3-4 times that, at least. The long endurance is largely because the X-37B carries a sizable solar panel, which is deployed from the cargo bay, unfolded and produces enough power to keep the X-37B going up there for a long time. The air force has not made public much about what the X-37Bs have been doing up there for over a total of 3,775 days so far.

The Space Shuttle was more ambitious and much more expensive, costing about $220 billion in current dollars and carrying out 135 orbital missions. The Space Shuttle program began in 1972 and ended in 2011 with the last launch in July 2011. Each manned Space Shuttle mission did not stay in orbit for long and the longest mission lasted 17 days (17 days, 15 hours). Six Space Shuttles were built and they carried out 135 launches and spent a collective 1331 days in orbit. Two Space Shuttles were lost in accidents, along with 14 crew. The first loss was in 1986 and the second in 2003. The manned Shuttle program did develop many of the features X-37B can now confidently use without a lot of orbital testing.

The X-37B space vehicle, according to amateur astronomers (who like to watch spy satellites as well), appears to be going through some tests much of the time. The X-37B is believed to have a payload of about 227-300 kg (500-660 pounds). The payload bay is 2.1x1.4 meters (7x4 feet). As it returns to earth, it is designed to 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). In contrast, the manned Space Shuttle was 56 meters long, weighed 2,000 tons and had a payload of 24 tons and a crew of up to eight people.

The X-37B has been in development since 2000 but work was slowed down for a while because of lack of money. Whatever the X-37B is now doing up there has been convincing enough to get Congress to spend over a billion dollars on it. 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. The X-37B is believed capable of serving as a platform for attacks on enemy satellites in wartime. Using a remotely controlled arm, the X-37B could refuel or repair other satellites. All this is speculative because, as a classified project, there is little confirmed information about its payload or mission, other than testing the system on its first mission. It is likely that future missions will involve intelligence work, and perhaps servicing existing spy satellites which use up their fuel to change their orbits. For regular satellite refueling missions a larger “X-37C” would probably be used. This is a scaled-up X-37B that would have a much larger (probably over a ton) payload. The X-37C could be quickly switched between cargo and passenger configurations. The X-37C would still be robotic and not require anyone onboard to control it. Work on the X-37C has apparently been halted because there are similar alternative designs that are closer to service.

The X-37B also demonstrated that it could not be easily tracked while in orbit. An international collection of amateur sky watchers proved remarkably adept at spotting orbital objects in the past, including classified ones like the X-37B. The amateur orbital observer community has concluded that one thing the X-37B tested was how well it could change orbits and stay hidden. In that respect, the X-37B was a resounding success. That's because these amateur observers are generally very good at tracking what's up there.

The X-37B has proved elusive and sometimes became 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, and the dedicated (and quite effective) amateur satellite watchers gave the X-37B quite a workout. China apparently seeks to do the same with their new Space Plane.

In the first week of August the Chinese Space Plane completed its second successful launch and is still in orbit. The first flight took place in early September 2020. China has yet to release any photos of what they call a reusable test spacecraft. There were satellite photos of the Chinese space plane after landing that showed a space plane similar in size to the American X-37B. The second launch and orbital activity was more closely observed. As of November, the Chinese UOV (unmanned orbital vehicle) is still in orbit.

The Chinese version of the U.S. Air Force X-37B UOV lands at a 5,000-meter (16,000 foot) landing strip near their Lop Nor nuclear test site in the Gobi Desert. The Chinese mentioned the X-37B when they first announced their effort in 2017. During its first flight, the Chinese UOV was spotted by an American space surveillance system releasing a smaller object into orbit. The Chinese UOV apparently released two such objects before returning to earth. The Chinese UOV remained in a 350-kilometer-high orbit for over 40 hours on its first flight and is using a similar orbit during its second mission.

The Chinese UOV was not a complete surprise as Chinese space officials mentioned such a project in 2017. It was believed they would test their UOV in 2020 and they did, but without any publicity until it landed safely. The only other nation to develop and use a spaceplane was Russia. The Buran project was similar to the American manned Space Shuttle and made one unmanned flight in 1988. This was for only two orbits before Buran was landed. The Soviet Union dissolved in 1991 and there was no money for further work on Buran. The one working Buran vehicle was stored in a hanger and destroyed in 2002 when the hanger collapsed. The European Space Program is developing a space plane as is India. The Chinese mentioned that their UOV as designed for at least 20 missions each.

One unanswered question is; what does X-37B or the Chinese UOV do up there? The X-37B operations are classified and little information about what happens in orbit is released. China seems to be equally secretive. The most recent X-37B mission caused a problem when the air force mentioned that the X-37B had carried and released three cubesats (very small satellites) that were not registered with the UN. That X-37B was known to be carrying ten cubesats to be released into orbit to perform various experiments. The Chinese appear to have done the same during their two days in orbit. The latest X-37B in orbit was reported to be carrying more items to put into orbit than any previous X-37B. The Chinese UOV released similar small satellites during its first flight, apparently to test the cargo launch system.

Cubesats are technically U Class spacecraft that can be no larger than 10 cm (about four inches) square and weigh no more than 1.33 kg (2.9 pounds). Cubesats are increasingly popular for science experiments by smaller organizations, or even individuals, who cannot afford a multi-million-dollar satellite that is ten or more times larger and heavier than a cubesat. Over 1,200 cubesats have been launched since 1998, with about 93 percent reaching orbit. That number is expected to double in the next few years because more and more commercial satellite launchers are providing unused space and weight on their launcher rockets for carrying and launching some cubesats. In some cases, the cubesat owners pay for this service while in other cases some cubesats are taken up for free, as a public service.

The U.S. is accused of using the unregistered cubesats launched from the X-37B as a test of a new anti-satellite weapon. A cubesat placed in the proper orbit could intercept and destroy or disable a much larger satellite. Or so the theory goes. The U.S. Air Force has no comment although two senior air force officials did mention, in 2019, that there were some secret anti-satellite projects underway. An anti-satellite weapon that is kept secret is more effective when used because the enemy doesn’t know what to prepare for.

Eventually some details emerge about older X-37B missions. It was eventually revealed that X-37B mission 4 tested a new thruster system for mobile satellites that needed to be tried out while in orbit. Also carried were dozens of different materials, possibly including some new spy satellite components to see what the harsh environment in orbit, especially radiation, can do. Such exposure can have unpredictable effects on materials and microelectronics after prolonged time in space.