This is the Zeroid Exploration Module 21, better known as the Z.E.M. XXI.
Released in 1970, this is one of several large accessories made for Ideal’s range of Zeroid robots.
A spring – loaded ratchet system opens the hatch and operates a lever in the cockpit on which the Zeroid is placed.
As the hatch opens, the landing legs flip down and the Zeroid robot trundles out.
It's a big toy, and with that unique ratchet system, requires no batteries.
I love the box artwork showing Zintar emerging from the ZEM which is set against a panoramic view of the Planet Zero.
Here's part of the instruction sheet.
In 1977 the ZEM was repackaged as the Star Hawk with a different colour scheme, as part the Star Team range to cash in on the Star Wars craze. This version only retained the ratchet feature.
Here's a short film showing the ZEM XXI in action.
The Zeroids will return.