Russia Breaks a Record
by James Dunnigan
July 24, 2014
On June 5th a retired Russian ICBM (a 217 ton RS-20/SS-18) launched a record 37 satellites at once (actually at 30 second intervals) after the third stage achieved the intended 630 kilometer high orbit. The RS-20 has a max satellite payload of nearly three tons. That means the average satellite weighed about 60 kg (132 pounds). Some of the 37 satellite were quite a bit heavier and most of the 37 were microsatellites (under 10 kg/22 pounds).
Russia only has a few dozen of the RS-20s left but three times as many of the smaller (106 ton) RS-18/SS-19 ICBMS for this sort of thing. These retired ICBMs have proved economical and popular for launching the growing number of highly capable but lightweight satellites. In August 2013 a RS-18 launched a South Korean 1.4 ton KOMPSAT 5 satellite that uses a radar that can detect objects and landforms as small as one meter (39 inches) across. This satellite is mainly for obtaining geographic (land and sea) information and supporting disaster response and environmental monitoring. While the satellite was new tech, the launcher was 1970s technology that was affordable and reliable because it was military surplus.
Russia still has about a hundred (out of a 1980s peak of 360) RS-18s in service and expects to keep some of them active into the next decade. Now it appears that most of these will be retired to satellite launching work. The 24.5 meter (76 foot) long RS-18 uses storable liquid fuel, meaning that the missile is inherently more complex to maintain than a solid fuel missile. Thus the older engines, and other components, of the first RS-18s to enter service are expensive to maintain but still in good shape to launch. Instead of nuclear warheads, the retired RS-18s are putting satellites into orbit before their engines become too old to be reliable. So far over 90 percent of the RS-18s used as satellite launchers were successful, which by any standard is exceptional. More importantly, liquid fuel rockets can lift a heavier load than solid fuel rockets so the last generation of Russian liquid fuel ICBMs (the RS-18 and RS-20) are superior as satellite launchers than American ICBMs (which since the 1980s have all been solid fuel). The last liquid fuel American ICBM, the Titan, was also converted to be a satellite launcher and many were later built just for that. The last of these was used in 2003.
The RS-18 entered service in 1975, and it wasn't until the 1980s that Russia began producing reliable solid fuel rocket motors large enough for ICBMs (the 45 ton RS-12M). The last RS-18s were manufactured in 1990, and Russia expects each of them to have a useful life of 30 years via the equipment improvements and careful maintenance. Older ones will often end up being used for satellite launches rather than scrap.
The RS-18 was developed as a "light" ICBM. In effect it was a competitor for the U.S. Minuteman series. The RS-18 was the first Russian ICBM to carry MIRV (Multiple, Independent Reentry Vehicles, which means each of six warheads in the missile had its own guidance system). The SS-19 carries six warheads. The RS-18 ICBM had a range of 10,000 kilometers. An RS-18 is converted into a satellite launcher by adding a third stage. Such missiles can lift 1.8 tons into orbit. Current technology enables small satellites (as small as 100 kg/220 pounds or less) to do useful work, and some RS-18 satellite launchers have carried many of these at once.
Over 550 of the RS-20s were built since the late 1960s and production ceased in the late 1980s. Most of the 300 remaining RS-20s were dismantled per disarmament agreements. About 59 remain in service and most of the remaining SS-20s may end up as satellite launchers. The RS-18 entered service in 1975 and over 500 were built by the end of the Cold War in 1991. These were basically the same technology as the SS-20, just smaller with a maximum payload of about four tons.
Since the late 1990s several countries in the West (especially the U.S.) have been developing very small satellites. The earliest small ones 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 weight 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 (piggybacking with a larger bird). 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.
These tiny satellites also have the advantage of being much more difficult to be tracked from the ground. If there are successful satellite attacks, then the nanosatellites can be sent up to replace the lost birds. The lightweight satellites (from CubeSats to 200 kg minisats) can be put in orbit using smaller, solid fuel, boosters. The U.S. Navy proposed using the ICBMs fired from SSBNs (ballistic missile carrying nuclear subs), which can be put to work much more quickly than the usual liquid fueled launcher. But the solid fuel ICBMs can only put a ton or more into orbit. With CubeSats and nanosatellites, this is not a problem. There are now standard nanaosatellites that are sold ready for the installation of your own payload.
Since the late 1990s the U.S. Air Force has been developing and launching lightweight (under half a ton) TacSat reconnaissance satellites. The first one (Tac Sat 2) was launched in 2002, while TacSat 3 went up in 2007, and was providing data to combat commanders in Afghanistan until early 2009. Troops on the ground could communicate with the TacSat, which provided photo-reconnaissance. Progress in this area has continued, although some of it is classified. Smaller satellites have become important for commercial uses and scientific research, both areas with much smaller budgets than the military.
The problem with these microsatellites is the cost of getting them into orbit. 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. That's why even smaller satellites became popular, because they were compact enough to be piggybacked with a larger satellite. This is becoming the most common way to launch the nano birds, keeping the cost down to under $10,000 per microsatellite. Launching dozens of them using a retired Russian ICBM has also proved economical.
| 
