Now that the menfolk have settled the planet, Mars needs women. (Although you kind of sense that Bradbury wishes it didn't.) Janice, Leonora—doesn't really matter. These two ladies stand in for all human women, everywhere. Like we said, Bradbury doesn't seem very interested in women.
(You can tell that he's not too comfortable writing about women, because this story relies on sewing metaphors, like calling the women "needles" (60) and comparing Janice's voice to a needle stitching words (73). It's like he thinks you have to use special lady language to talk about women.)
Other than their final destination, we don't learn too much about these women. They're friends; they seem to have a pattern where Janice worries and Leonora calms her; and they live in Independence, Missouri.
We're thinking that name is significant. Are these women independent? Are they going to become independent when they go to Mars? Or is the name ironic—are they, in fact, very dependent?
Janice is traveling to Mars to marry her sweetheart Will, even though she's terrified of space travel due to a childhood trauma. (She fell down stairs and got stuck in a closet once. Okay, so it may not be the most dramatic trauma, but it's her trauma.)
We're not sure why Leonora is traveling to Mars. Maybe just to make sure that Janice doesn't freak out on the trip.
Although she's a little prone to panic, Janice does a lot of thinking about how the trip to Mars is like the trip the American settlers made to the West in the 19th century. She's one of the prime sources in the book to make that connection between Mars and the American frontier, like when she's packing up her tasty-sounding food pills:
Janice lifted a matchbox of food pills, calculating the totals of things carried in those high-axled, tall-bedded wagons. For each man, each woman, incredible tonnage! … Yet here, today, pills that fit a wristwatch fed you not from Fort Laramie to Hangtown, but all across a wilderness of stars. (6)
Got it? These women are here mostly to show us that we've moved on to a new set of stories. No more exploring and conquering; now it's time to settle down, transform the land, and build new lives. You know, lady stuff.