From VOA Learning English, this is Science in the News.I'm Anna Matteo.And I'm Christopher Cruise.Today we report on recent developments in space science.We tell about the growing demand for communications satellites and space-based imaging services.We also tell about China's first robotic vehicle on the moon.But first, we examine the effect of longer space flights on humans.Human beings have a natural desire to explore the unknown.People with a strong interest in space like to say it is the last place left to explore.But scientists are warning that space exploration for long periods is not going to be easy.