Public domain This file is in the public domain because it was created by NASA and the European Space Agency. Hubble material is copyright-free. Material published by NASA may be freely used as in the public domain without restriction, although NASA requests credit and notification of further use. ESA requires that they be credited as the source of any of their material that is used. The material was created for NASA by STScI under Contract NAS5-26555 and for ESA by the Hubble European Space Agency Information Centre. [1] or [2].