Read "Search the Sky" by Frederik Pohl online for free on Textopian. Full text with search, annotations, highlights, and AI-powered reading aids.
There was a home base, a gigantic island called Australia, to which they took Ross and Doc Jones in a little car that sprouted no wings and flashed no rockets, but flew.
They lived underground there, invisible to goggling passengers and crewmen aboard the "rockets. " (They weren't rockets. They were turbojets. But it made the children happy to think that they had rockets, so iron filings were added to the hot jet stream, and they sparkled in magnificent display.)