Through most of 1966, it was still reasonable to assume that NASA and the United States might enjoy an expansive post-Apollo future off the Earth. Manned missions beyond the moon were expected to evolve from programs already in place; namely, the Apollo lunar landing program, the joint NASA/Atomic Energy Commission NERVA nuclear-thermal rocket program, and the Apollo Applications Program of advanced lunar missions and Earth-orbiting space stations.
With these programs in mind, in March 1966 the American Institute of Astronautics and Aeronautics and the American Astronautical Society jointly convened the Stepping Stones to Mars conference in Baltimore, Maryland. It would, as it turned out, be the last major Mars-focused engineering meeting until the 1980s.
Attendees heard a team of engineers from NASA’s Marshall Space Flight Center (MSFC) in Huntsville, Alabama, describe a piloted Mars mission based on both high-thrust NERVA-II nuclear-thermal rockets and low-thrust nuclear-ion (electric) propulsion. The study team’s leader was veteran German-born rocketeer Ernst Stuhlinger, the director of MSFC’s Research Projects Laboratory.
Stuhlinger had begun his work on ion propulsion in the 1930s. He earned a Ph.D. at age 23, then worked for Hitler’s nuclear program. In spite of his science training, in 1941 he was drafted into the Wehrmacht and sent to the Russian front. After suffering wounds in the Battle of Moscow and surviving the Battle of Stalingrad, he was reassigned to Wernher von Braun’s rocket team at the Baltic Sea rocket base of Peenemünde in 1943. There he worked on the guidance system for the V-2 missile. He arrived in the U.S. in 1945 courtesy of the U.S. Army with von Braun, 124 other German rocketeers, and a trainload of captured V-2 missiles. Stuhlinger resumed his ion propulsion work in Huntsville in the early 1950s, while von Braun’s team was part of the Army Ballistic Missile Agency at Redstone Arsenal. Under von Braun’s leadership, the Peenemünde rocketeers became the nucleus around which NASA MSFC coalesced in July 1960.
In the years before the Stepping Stones to Mars meeting, Stuhlinger had put forward several ion-drive spacecraft designs. His 1954 Sun Ship would have relied on concentrated sunlight for electrical power to drive its ion thrusters, but his other designs – the 1957 Mars and Beyond and 1959 lunar ion freight disc ships and his 1962 lunar ion freighter and 1962 spinning ion Mars spacecraft – would have employed large nuclear reactors.
On April 12, 1961, the Soviet Union launched Yuri Gagarin into space on board the spherical Vostok 1 spacecraft, making him the first human to orbit our planet. His flight helped convince a politically precarious President Kennedy (this was just after the Bay of Pigs) to put America on course for the moon. Just 20 years later, on April 12, 1981, the U.S. launched the first Space Shuttle Orbiter, Columbia, on a two-day test flight designated STS-1. Moonwalker John Young and rookie Robert Crippen put Columbia through her paces. After landing on the dry lake bed at Edwards Air Force Base, California, Young enthused that “We’re not really too far – the human race isn’t – from going to the stars.” The flight helped to convince President Reagan that space made for great photo ops – and to call for a U.S. space station by 1994 during his 1984 State of the Union speech.
It’s 51 years since Gagarin’s flight and 31 years since STS-1. The Soviet Union lost the lead in the Space Race within a few years of Gagarin’s flight, then shifted its human spaceflight emphasis to evolutionary space station development. The Space Race ended after the Soviet Union collapsed in 1991. Columbia, returning to Earth after the three-week STS-107 flight, broke apart over Texas on February 1, 2003. In January 2004, President Bush announced that the Space Shuttle would retire in 2010.
The U.S. and the Soviet Union had already begun moves toward greater space cooperation by the time the Soviet Union fell apart, and this cooperation rapidly gained momentum under President Clinton. This meant that, when Columbia broke up, American astronauts could still reach the International Space Station – which was built around a near-copy of the Russian Mir space station – on board Russian Soyuz spacecraft. Soyuz would become their only ride to space in 2011, after President Bush failed to adequately fund the Shuttle’s replacement.
It is still too early to know how America’s temporary reliance on Russian spacecraft will play out; some say that, while Bush’s failure created a gap in America’s ability to launch astronauts on its own, it also opened an opportunity for U.S. private enterprise to take over the workaday business of ISS crew and cargo deliveries. This will, they say, free NASA to develop the technologies it needs to renew human spaceflight beyond ISS orbit. Many in the U.S. chafe at reliance on Soyuz, the world’s most reliable spacecraft, but I marvel at how far we’ve come. Human spaceflight was about U.S.-Soviet Cold War competition when Yuri Gagarin flew in 1961; by 2011, it was about U.S.-Russian-European-Canadian-Japanese human spaceflight interdependence.
I also wonder why, if some so feared reliance on the Russians, they didn’t protest the Shuttle’s cancellation in 2004, or the persistent underfunding of its replacement in the years that followed. I wonder why they persist in blaming President Obama for the Shuttle’s retirement, when in fact those wheels had been set in motion long before he took office. One might suspect them of partisanship, though of course nothing so petty could ever be part of humankind’s grand push into space. (You cannot see me as I type these words, but I am holding up a big sign that says, “The previous sentence was written with tongue planted firmly in cheek.”)
Beyond Apollo is a space history blog. Typically my horizon is about 10 years in the past because it is impossible to place in reliable context anything more recent. On this anniversary day, however, I will look to the future and offer words of cautious hope. The wall between the U.S. and Soviet space programs collapsed 20 years ago; the wall between the U.S. human and robotic programs is now falling. (Actually, this process commenced a few years after Gagarin’s flight, but institutional rivalries within NASA slowed its progress.) The partition was always artificial; when Columbia broke up over Texas, it was a robot carrying passengers through a flight regime no human could navigate. Soon, the human and robotic spaceflight sides of NASA will have little choice but to openly merge. Out of this merger will come synergies that will propel humans of many countries across the Solar System.
Perhaps in 20 years, the Russian spaceship Yuri Gagarin, with a European commander, will orbit Mars while a Japanese geologist teleoperates a Canadian humanoid robot on the planet’s surface. The Gagarin will revolve slowly to provide a healthy dose of artificial gravity to its human crew. Perhaps that geologist will raise his robot hand and take a moment to brush the accumulated red dust off the Columbia memorial on the derelict rover Spirit in Gusev crater. Meanwhile, Chinese and Brazilian teleoperated robots will dig and pour marscrete, preparing a radiation shelter for flesh-and-blood humans. Perhaps the U.S.-built Mars lander Columbia will set down nearby with no pilot on board and the first human to set booted foot on Mars, an astronaut from India, will step out among the robots.
The details of this vision do not matter. What matters is the realization that there is little cause for discouragement on this anniversary day. We have come a long way in a short time and are spoiled for possibilities. In fact, some of us might feel defeated in part because we have so many opportunities in front of us that it is hard to choose. This tends to split the small community of die-hard space supporters along sectarian lines, so that we spend far too much time and energy arguing with each other. The fact is, choosing is foolish, for everything our warring sects can imagine can be – will be – part of our future in space.
Ernst Stuhlinger, director of the Research Projects Division at NASA’s Marshall Space Flight Center in Huntsville, Alabama, first studied ion (electric) propulsion in Nazi Germany in the 1930s, when space travel seemed a distant dream. Barely three decades later, much had changed. On May 25, 1961, new President John F. Kennedy had put NASA on the road to the moon. Ten months after that epochal event, Stuhlinger and Joseph King, an engineer in Stuhlinger’s division, told participants in the American Rocket Society’s Electric Propulsion Conference that it was “generally accepted that a manned expedition to. . .Mars will be carried out soon after such an ambitious project becomes technically feasible” because it was “the natural follow-on project to be undertaken after the [Apollo] lunar program.”
They also stated what many in their audience must have already understood: that ion propulsion could provide constant low-thrust acceleration while expending much less propellant per ton of spacecraft than either chemical or nuclear-thermal propulsion. Less propellant would mean fewer costly rocket launches to place spacecraft components and propellant into low-Earth orbit (LEO).
Stuhlinger and King then described their plan for an ion-drive Mars expedition. They did not offer an expedition start date, though they did say that it would take place in the early 1980s, about 20 years after their presentation. Large Saturn-class or enormous “post-Saturn”-class chemical rockets would launch “modular subassemblies” into LEO, where assembly crews would bolt them together. The expedition would comprise five 150-meter-wide nuclear-powered ion-drive spacecraft of two types. Three “A”-type ships would carry one 70-ton Mars lander each (image at top of post). Two “B”-type ships would lack landers. Each of the five vessels would carry three astronauts on board. The expedition could continue as planned if as many as two ships were lost, provided that they were not of the same type. In an emergency, one ship could return the entire 15-man expedition complement to Earth “under crowded conditions.”
There is something whimsical about Stuhlinger and King’s Mars spacecraft design. The Mars fleet’s five ships would revolve like slow propellers, 1.3 times per minute, glinting in the blackness and raw sunlight of space. The twin ion-drive propulsion units, mounted on booms at the center of rotation, would glow an unchanging light blue. They would counter-rotate, so would always remain pointed in one direction; that is, they would not spin with the rest of the ship. The ship’s 4300-square-meter diamond-shaped radiator, made up of eight panels, would glow cherry red. Streamlined, finned Mars landers would resemble classic science-fiction spaceships – or the V-2 missiles that Stuhlinger had helped to develop during the Second World War, when he was a member of Wernher von Braun’s rocket team.
Ernst Stuhlinger was one of Wernher von Braun’s compatriots at Nazi Germany’s Baltic Sea rocket base of Peenemünde. He worked on missile guidance systems. At the end of the Second World War, he became one of 126 German rocketeers spirited to New Mexico by the U.S. Army. He worked beside von Braun at the Army Ballistic Missile Agency at Redstone Arsenal in Huntsville, Alabama, and helped to lead the team that launched the first successful U.S. satellite, Explorer 1, on January 31, 1958. In mid-1960, he transferred to NASA with the rest of von Braun’s group to form the nucleus of NASA’s Marshall Space Flight Center.
Ernst Stuhlinger poses with a model of a Redstone missile. The Juno rocket, a Redstone derivative, launched Explorer 1, the first U.S. satellite, in January 1958. Image: NASA.
Stuhlinger had worked in Hitler’s nuclear and missile programs, but ion propulsion was his first love. In a paper presented in Japan a year before his transfer to NASA, Stuhlinger proposed an innovative split lunar transportation system which would see passengers reach a moon base, 238,000 miles away, in from 40 to 60 hours on board high-thrust chemical-propulsion spacecraft. These would “pierce through the Van Allen radiation belts in a sufficiently short time to keep the passengers safe.” Cargo, meanwhile, would reach the moon on unmanned nuclear-powered ion freighters, which Stuhlinger dubbed “cargo ferries.” These low-thrust spacecraft would, Stuhlinger explained, “need several weeks for the one-way trip, but [would] offer a payload-to-weight ratio which is superior. . .to that of high-thrust vehicles.” In other words, an ion-propelled spacecraft could deliver a lot of cargo while expending minimal propellant. Both the fast chemical and slow ion spacecraft would depart for the moon from a space station in 600-kilometer-high Earth orbit.
Stuhlinger’s 1959 lunar cargo ferry design included a nuclear reactor at the end of a long slender boom. The reactor would heat a working fluid which would drive a turbine. The turbine would turn a generator that would provide the cargo ferry’s ion drive with electricity. The ion drive, a conical cluster of thrust chambers positioned to thrust at a 90° angle relative to the reactor boom, would draw propellant (probably cesium; Stuhlinger was not specific) from a spherical propellant tank. A pair of radio dish antennas on booms would enable operators at the Earth-orbiting station and the lunar surface base to remotely control the cargo ferry, which would include little or no automation. A crane-like arm would support a cylindrical cargo lander.
The cargo ferry’s most distinctive feature was probably its disc-shaped radiator, which was designed to cool the working fluid after it passed through the turbine. The radiator was positioned so that it would be edge on to the Sun as the cargo ferry moved through space, so that most of it would not be in direct sunlight. The radiator would rotate to drive working fluid to its outer edge, where it would be pumped back to the reactor.
Image: Frank Tinsley/American Bosch Arma Corporation
Ernst Stuhlinger earned his Ph.D. in Physics in 1936 at the age of 23 and went to work for the German nuclear program in 1939. Despite his scientific credentials, he was drafted in 1941 and sent to the Russian front. In 1943, after surviving the Battle of Stalingrad, he was assigned to work on guidance systems in Hitler’s V-2 missile program.
Stuhlinger owed his place in the Guided Missile Development Division at Redstone Arsenal in Huntsville, Alabama, to Operation: Paperclip, the U.S. Army’s effort to retrieve rocket engineers and V-2s from the smoking ruins of the Nazi empire. Stuhlinger and the 125 other Paperclip Germans made the U.S. Army’s job easy; they defected as a group to the American side in the chaotic closing days of the Second World War in Europe.
The U.S. military was, of course, mainly interested in tapping their talents to build missiles, but several of the Germans did their energetic best to cultivate other aspects of rocketry in the United States. For example, the most famous of the German rocketeers, Wernher von Braun, set out in the early 1950s with help from Collier’s magazine and Walt Disney to promote space stations and moon and Mars expeditions to the American citizenry. Stuhlinger helped von Braun in his efforts to sell spaceflight and engaged in outreach efforts of his own.
In a paper presented at the Fifth International Astronautical Federation Congress in 1954, for example, Stuhlinger pitched interplanetary travel using low-thrust ion (electric) propulsion, a technology that he had first studied while in Germany. The spacecraft design he proposed – which he nicknamed the “Sun Ship” – comprised three major parts: the crew/payload compartment at the ship’s center; a 146.4-ton multi-unit solar-electric power system; and a multi-chamber low-thrust ion-drive rocket system.
I research and write about the history of space exploration and space technology with an emphasis on missions and programs planned but not flown (that is, the vast majority of them). Views expressed are my own.