British broadcaster ABC airs the second episode of Pathfinders To Venus, a follow-up series to Pathfinders In Mars, produced by future Doctor Who creator Sydney Newman. George Colouris and Gerald Flood (City Beneath The Sea) star; the script is written by Malcolm Hulke (Doctor Who) and Eric Paice (Star Maidens). Though the original master tape of this episode was later wiped for reuse, film recordings of all eight episodes will be recovered and released on DVD in the 21st century.
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The 108th episode of Doctor Who airs on the BBC. This is part two of the story now collectively known as 
The 25th episode of the time travel sitcom It’s About Time, created by Sherwood Schwarz (I Dream Of Jeannie) and starring Frank Aletter, Jack Mullaney, and Imogene Coca, is broadcast on CBS.
The 83rd episode of Irwin Allen’s adventure series Voyage To The Bottom Of The Sea airs on ABC, starring Richard Basehart and David Hedison. Terry Becker guest stars.
The 41st and 42nd episodes of Larry Cohen’s science fiction series The Invaders, starring Roy Thinnes and produced by Quinn Martin’s QM Productions, is broadcast on ABC. Diana Muldaur (Star Trek: The Next Generation), Barry Morse (Space: 1999), Suzanne Pleshette (The Bob Newhart Show), Dana Elcar (MacGyver), and Barry Williams (The Brady Bunch) guest star.
Toho releases 
Alpex Corporation, an American computer company, files “the ‘555 Patent” for a “television display control apparatus” capable of loading software from ROM chips embedded in swappable cartridges and other media. This patent effectively shifts the infant video game industry from a hardware-based model to a software-based model, and is licensed by Fairchild Semiconductor for the first cartridge-based video game, the Fairchild Video Entertainment System (later known as Channel F), a year later; the resulting sea change forces a sudden reassessment in the R&D departments at Atari and Magnavox, among others. Due to the remarkably broad nature of patent #4026555, Alpex will be able to take nearly every video game manufacturer to court to force them to license the technology from Alpex through the early ’90s. The first major challenge to Alpex’s patent will come from Nintendo in 1986, a case that will eventually make its way to the U.S. Supreme Court in 1997 – by which time Alpex will go bankrupt pursuing the case.
The 
The third episode of Harold Jack Bloom’s sci-fi series Project UFO airs on NBC, portraying fictionalized investigations into what the show claims are actual cases from the U.S. Air Force’s Project Blue Book investigations. William Jordan (Beyond Westworld) and Caskey Swaim star. Rod Perry (S.W.A.T.) guest stars.
The seventh episode of the series Salvage 1 airs on ABC, starring Andy Griffith, Joel Higgins (Silver Spoons), and Trish Stewart. Richard Jaeckel (Spenser For Hire) and Barry Nelson (My Favorite Husband, The Shining) guest star.
The 
The Soyuz T-4 mission lifts off from the Soviet Union, carrying a two-man crew to space station Salyut 6. Cosmonauts Vladimir Kovalyonok and Viktor Savinykh remain about the station for 75 days, and are the last long-duration crew to occupy Salyut 6. Since they are still in orbit in April, they become the first Soviet crew to orbit the Earth at the same time as an American manned space vehicle since 1975, though the two never interact with each other at any point. The Soyuz T-4 capsule remains at the station as the escape vehicle until this crew departs in May.
NBC airs the 
The legendarily tough arcade game 
CBS airs 
The week-long national syndication window opens for 
Fox Network airs 
Warner Bros. releases 
The 
The 37th episode of Lois & Clark: The New Adventures Of Superman airs on ABC, starring Dean Cain and Teri Hatcher. Mark Rolston and Robert Culp guest stars.
Showtime airs the 94th episode of The Outer Limits, a revival of the 1960s science fiction anthology series. Malcolm McDowell guest stars in an episode based on a story by Harlan Ellison and A.E. Van Vogt.
Pay cable channel Showtime premieres the 
The 
Sci-Fi Channel premieres 
The 153rd episode of Chris Carter’s modern-day science fiction series The X-Files airs on Fox, starring Gillian Anderson and David Duchovny. Billy Drago (The Untouchables) guest stars.
Big Finish Productions 
Sci-Fi Channel premieres 
The 117th episode of Joss Whedon’s supernatural series Buffy The Vampire Slayer, starring Sarah Michelle Gellar, airs on UPN. James Marsters, Anthony Stewart Head, and Alyson Hannigan also star.
NASA’s Hubble Space Telescope makes an astonishing discovery while observing one of the first planets discovered beyond Earth’s solar system. The gas giant planet designated HD 209458b, orbiting the star HD 209458 in the constellation of Pegasus, 150 light years from Earth, is losing its atmosphere. Slightly larger than Jupiter, but locked into a dizzyingly tight orbit around its star (only 4,000,000 miles, with its “year” lasting less than half of an Earth week), HD 209458b’s atmosphere is boiling away into space thanks to the heat of the nearby star. This leads to a new exoplanet classification, “Hot Jupiters,” used to describe gas giants in similarly suicidal orbits. The core of HD 209458b will probably not last long once the last remnants of its atmosphere dissipate.