Listen to "NBC Nightly News," providing reports and analysis of the day's most newsworthy national and international events. This audio podcast, updated each weekday evening by NBCNews.com, brings you the day's show in its entirety. For more from "Nightly News", visit http://www.nbcnews.com/nightly-news
Two art projects aim to raise questions about what gets sent to space and what lingers after. Chief Environmental Affairs Correspondent Anne Thompson reports on how they’ve sparked debate among astronomers.