Aboard China's Tianzhou cargo missions, researchers from Shanghai and Tsinghua have quietly pursued one of humanity's most consequential questions: whether life can renew itself beyond Earth. Their findings, published in Science Advances, reveal that the cosmos does not easily yield to biology — reproductive cells falter in microgravity, developing at half the rate and with a fraction of the vitality they show on Earth. It is not a verdict against the dream of space habitation, but a reminder that the universe does not simply accommodate our ambitions; it asks us first to understand its terms.