Between seasons 1 and 2 of SPACE:1999-remember that the first season was shot from 1973-1974 but wound up not appearing on US or UK TV until Fall '75 and season two started up in late 1976- Gerry Anderson was asked to make a quick Sci Fi show for NBC's SPECIAL TREAT (which was NBC's occasional answer to ABC's Afterschool Specials). The trick was it had to be a thinly veiled science lesson for the kids. In this case, it vaguely remakes the LOST IN SPACE concept, this time about two distinct family units on a spaceship that is to accelerate to light speed, to journey to the star Alpha Centauri, but then, due to a mishap , they get sucked into a black hole and taken to another universe. Brian Blessed and Nick Tate-both SPACE:1999 veterans play the elders. Tate drops his Aussie accent in this show so he'd be easily understood by US kiddies, and, to not come across like his Alan Carter character. They use some rather flatly lit spaceship sets from Year 1 of SPACE:1999(the inside of The Ultra Probeship from Dragon's Domain) very crudely re-dressed. The costumes seem a thrown together affair as well. All the money seems to have been spent on a new model of the spaceship "The Altares" however, it's poorly photographed, even by the standards of SPACE:1999(which at the time were quite good). Too many strange lens flares are used and the black hole looks like a really cheap effect(unlike the rather good matte painting from the Space:1999 episode "Black Sun"). The music score, not done by Anderson regular Barry Gray, was done by Derek Wadsworth who did the electronic jazz theme music to Season 2 of Space:1999. It further makes the effort seem quick and cheap.
The best attention is paid to the science, which is explained in correct, but expository dialogue that lets us know this is a science lesson, in fact.
The quick, hour long film is known as THE DAY AFTER Tomorrow in the US and, INTO INFINITY in the UK. It was filmed very quickly, in something like 9 days before SPACE:1999 Year Two had geared up. It was in fact longer with extra footage in foreign markets as it was sold to Europe as a feature length film. Fanderson-the Gerry ANderson Fan Club-issued the film on VHS and eventually DVD, a few years ago exclusively through them.