XMP13 - Experimental Moon Probe 13 - is a planned three-man circumlunar flight. It runs into a snag, and the word "brenschluss" is introduced to an American popular audience.
Col. McCauley commands a four-man lunar landing mission, but one of the men is injured en route only to conceal his injury rather than abort the mission.
The first two sections of a circular space station are mated in orbit, but not without incident.
Col. McCauley's team suffers a casualty while setting up the beginnings of a moon base, and are told that he cannot survive the acceleration of takeoff.
When the first remote-controlled nuclear missile goes off course and threatens a lunar expedition, its guilt-ridden creator insist on accompanying McCauley to try and remove the nuclear pile before it's too late.
McCauley leads a team to the moon to conduct seismographic experiments, but communications officer Tom Farrow is distracted by news that his wife was in a car accident. Things take a turn for the worse when a moonquake knocks the ship over and Tom disappears down a fissure.
McCauley is sent on a rescue mission when manned probe MR127 goes silent halfway home from the moon.
Skyra, a three-mile asteroid, has unexpectedly settled into Earth orbit at 3,000 miles altitude, and McCauley leads a mission to investigate the possibility of turning it into a space station.
When a meteor strike takes out the reserve oxygen supply on McCauley's ship, he and his two crewmates must do whatever it takes to survive for their rendezvous with Space Station Astra before they asphyxiate.
A new alloy holds the promise of an improved re-entry vehicle, but during the first manned test astronaut Gibson is forced to eject, overruling Stark's objections and what the instruments say.
The Air Force decides to determine how woman can handle living on the moon, and choose Major Joe Hale's wife Renza. Joe is initially happy to have his wife along, but the couple soon begin bickering when Renza feels cooped up, forced to cook for the men.
McCauley takes two astronomers up to the moon on Christmas Day, but when one of them is trapped in an isolated observation post with appendicitis, only a miracle can save him.
A physicist and biologist don't get along on Earth, but each makes sure that they're assigned to the same two-week workshift on Space Station Astra. However, when one of them is endangered, the other one must put his life at risk to help his associate.
McCauley recruits two brothers to handle the precision flying necessary to do inflight refueling in space.
A pair of new astronauts find out the hard way why McCauley is such a stern taskmaster.
A solar electrical disturbance leads to a crash landing on the far side of a mountain range from the moonbase. McCauley must get his co-pilot and two scientists to the moonbase... but one man must die so the other three can live.
A cocky electrical technician who aspires to be an astronaut stows away on McCauley's flight, but his presence leads to an electrical short that deprives the ship of power. And without power, the spaceship will soon plummet into Earth's atmosphere and burn up.
A scientist driven by a secret personal tragedy attempts to validate his theory of ice on the moon. However, his obsession soon puts McCauley and his crew at risk.
A cocky reporter wins a drawing to go to the moon and plants a fake story that he plans to announce on a worldwide live broadcast, assuring him high ratings.
McCauley accompanies two geochemists on an expedition to the moon to confirm the existence of radioactive deposits. However, the jealousy of one scientist threatens the other.
When a sample of the rare Specimen 9 turns up in the hands of an industrialist, McCauley realizes that someone on his last expedition brought it back from the moon. Now he must take the four scientists back to the moon and trick the guilty party into revealing himself and the location of the deposit.
Three astronomers apply for a mission where only two can be chosen. The two men fight over the opportunity to marry the third, Muriel, to assure that they are the ones chosen. Meanwhile, Muriel deals with their romantic interests as well as what she perceives as condescending treatment from McCauley.
McCauley must choose between duty and retribution when he discovers that the scientist he's escorted to Space Station Astra was the hit-and-run driver that struck his son Peter.
A piece of manufactured metal from a debris cluster strikes a spaceship as it returns to Earth, and McCauley is assigned to go up and recover more specimens. However, meanwhile the three members of the original crew die one by one in mysterious accidents.
McCauley and his three-man team encounter mysterious phenomena on the moon which suggests that some alien life form is stalking them.
Scientist Guthrie Durlock is determined to help recover his errant Venus rocket. McCauley refuses to let him go because Guthrie disobeyed him on a previous mission, but Guthrie goes over the colonel's head. However, the recovery mission becomes dangerous when the two ships become magnetically charged, making it impossible to approach safely.
Captain Kyle Rennish loses his wife in a car accident and his daughter has trouble accepting her mother's loss. Nonetheless, he goes on a photo recon mission to the moon with McCauley, and discovers a strange manmade metal object.
Two scientists come aboard Space Station Astra to test equipment that allows them to determine when a crewman has reached the breaking point and must be relieved of duty. However, when a malfunction causes the station to rotate out of control, McCauley must go beyond his breaking point to save the lives of his men.
McCauley makes an unconfirmed sighting of a fossil impression on an asteroid. However, his superiors suspect that he may be suffering from stress and order him grounded, leading McCauley to wonder if his friends are turning against him.
When the son of a friend is trapped on a spaceship rocketing out into the solar system, McCauley launches a desperate rescue attempt aboard an experimental ship.
McCauley and two men take up duty at a lunar observatory on the far side of the Moon. When one of them is injured, they start picking up strange rhythmic signal from a planet 200 light-years away.
The arrivals of the Russians on the Moon sparks off a friendly rivalry when both sides work to launch a Mars flight first. Both ships launch, and when the Russian ship suffers an accident, McCauley has to decide whether to go to their aid or reach Mars.
McCauley launches a desperate rescue attempt to save two officers trapped on the Moon with only two hours of oxygen. The men take refuge in a cave and boil off liquid oxygen to breathe... but an avalanche seals off the cave mouth.
A Russian commander crash lands his ship on the Moon. To cover up his apparent incompetence, he sneaks into the American moonbase while McCauley and his men conduct a search, and then locks them out as their oxygen supply dwindles away.
McCauley supervises a project to launch atomic waste into the Sun for safe disposal. He finds himself working with a former Air Force pilot who retired after a re-entry accident, and discovers that the man now has a dangerous lack of confidence in his work.
McCauley is sent to England to help the British Rocket Group develop their Vega Rocket. When he learns that they plan to use first-stage rockets as second-stage boosters, McCauley advises against it. His advice is ignored and he soon has to mount a rescue mission when Vega tumbles out of control.
En route to the Moon, McCauley and his crew spot a mysterious object that holds to a parallel course. A later ship spots the object and follows it, and disappears under mysterious circumstances. Now McCauley vows to find the object and solve the mystery.
McCauley leads the first expedition to Phobos, the moon of Mars. Dr. Morrow, the lead scientist, insists on making his observations. When a fuel leak forces them to cut the mission short, Morrow disappears and McCauley has to find him before they are forced to depart.