Apparatus including a boom to be compressed and rolled up

An apparatus for unfolding a solar sail, comprising:

• a least one boom including a tip and a foot and being designed and arranged to be rolled up to form a roll, said tip being located in a radial inward region of said roll and said foot being located in a radial outward region of said roll;
• a unit being designed and arranged to unfold said at least one boom and including a bearing being designed and arranged to cooperate with said foot in a way that said foot at the beginning of the unfolding process has an enlarged cross section;
• and
• at least one solar sail being operatively connected to said boom to be unwound together with said boom.

A solar sail unit, comprising:

• a plurality of booms each including a tip and a foot and each being designed and arranged to be rolled up to form a separate roll, a tip being located in a radial inward region of each roll and a foot being located in a radial outward region of each roll;
• a plurality of units each being designed and arranged to unfold one of said booms and each including a bearing being designed and arranged to cooperate with said foot of said one of said booms in a way that said foot at the beginning of the unfolding process has an enlarged cross section;
• and
• a solar sail including a plurality of partial sails each being operatively connected to at least one of said booms to be unwound together with said boom.