Facebook Explains Mark Zuckerberg's Disappearing Messages. 3 Things to Know Today.Here's what you should know today about Mark Zuckerberg, Sheryl Sandberg, space travel and emerging jobs. Stay in the know in 60 seconds.

Facebook explains Mark Zuckerberg's messages disappearing from recipients' inboxes as a corporate security measure, and Sheryl Sandberg says Facebook knew about Cambridge Analytica's mishandling of user data more than two years ago. In other news, there's already a waiting list to stay in the very first luxury space hotel -- and LinkedIn's new jobs report reveals the top two emerging titles.

Update:A Facebook Messenger spokesperson contacted us with the following statement: "People using our secret message feature in the encrypted version of Messenger have the ability to set a timer — and have their messages automatically deleted. We will now be making a broader delete message feature available. This may take some time. And until this feature is ready, we will no longer be deleting any executives' messages. We should have done this sooner — and we're sorry that we did not."