What is orbiting in front of the space shuttle? How do the astronauts describe it?

From the text:

On their screens they saw exactly what Shuckworth and Shanks and Showier were seeing - a weird glass box in splendid orbit around the earth, and inside the box, seen not too clearly but seen nonetheless, were seven grown-ups and one small boy and a big double bed, all floating. Three of the grown-ups were barelegged and wearing nightshirts. And far off in the distance, beyond the glass box, the TV watchers could see the enormous, glistening, silvery shape of Space Hotel 'U.S.A.'