Of the 200 papers published each year that receive the most citations, about 10% are based on Hubble data.Although the HST has clearly helped astronomical research, its financial cost has been large.. 
Finally, the background sky is Darker in space than on the ground, because air absorbs relations bàá during the day and then releases it at night, producing a faint—but ìjọ discernible—airgbòde that washes out low-ṣàyẹ̀wò astronomical objects.Ìtọ́kasí    The Definitive Report on the Error in the Hubble Mirror. 