Tweel (A Martian Odyssey) Tweel (A Martian Odyssey) Tweel (also referred to as a "Tweerl", the exact pronunciation of the word is said to be impossible for humans) is a fictional extraterrestrial from the planet Mars, featured in two short stories by Stanley G. Weinbaum. The alien was featured in "A Martian Odyssey", first published in 1934, and "Valley of Dreams" four months later. Weinbaum died of lung cancer soon after, and a third installment in the series never saw fruition. Tweel remains one of the most recognised aliens in early science fiction, and is said to be an inspiration for aliens in the
Human mission to Mars considerations for using aerocapture on crewed missions is a maximum G-limit to experience, for which it was noted 5-g's (5 times Earth gravity) was a common limit to be planned for. There may be several landers, for example, separate ones for the crew, a habitat, rover, supplies, ascent vehicle, etc. Landed spacecraft on the surface of Mars: One of the big challenges to landing on Mars was overcome by Mariner 4, when it showed the properties of the atmosphere. Another was a basic survey of the planet, to know what place might be suitable to land. This has been overcome