An inspiring year-long science contest—can we say voyage?—is about to come to an end in a most spectacular way. In the grand finale of YouTube Space Lab (powered by Lenovo), three teenagers will have their science experiments performed by astronauts high above Earth at the International Space Station.
Best of all, we can watch the event unfold; it will be brought to us in the world’s largest-ever live stream from space. The awesome Bill Nye “The Science Guy” will serve as host. Click the link to go to the YouTube Space Lab channel, where the online broadcast will take place.
We got to wondering how the heck a live stream works—and particularly one this complex—so we asked the guys who are in charge of making it happen. David Thorpe (Live Streaming Operations) and Marc Joynes (Creator Space Manager) from Google/YouTube shared the story via email.
Thanks for answering our questions. We're naturally very excited about the largest-ever live stream from space. Tell us from a technical standpoint how a live stream works normally, and then explain how this particular one might be different.
YouTube live streams hundreds of events every day, so we're used to providing our audience with live music, news, sports and entertainment. But we've never streamed from space before, so this is an exciting new frontier for us! Live streams work by making sure we get the video signal to the user as quickly as possible, from the source to the destination. Unlike normal videos, we have to minimize buffering and delay so we concentrate a lot on ensuring the network remains speedy from the event all the way through to the user's computer. The other problem doing things live is that if something breaks during the event, there's really no second chance to put it right. So we have backups for everything we do and we test a lot. For the YouTube Space Lab event, we've spent a lot of time getting everything right to give the viewer the best experience possible and we're confident it will be an amazing experience.
Where did you begin in the planning for the linkup with the International Space Station and what new challenges did you face based on its position a couple hundred miles above us?
We've worked closely with NASA for about six months to ensure we are able to get the presenter Bill Nye, who will be in a London studio, a direct link to Sunita Williams in the International Space Station (ISS). We've installed two audio lines from the studio in London to the Johnson Space Center (JSC) in Houston—one to the mission control desk and another which is routed from JSC to the ISS. In addition, there's a video link from the ISS to JSC, who then relay the video signal to the studio via satellite. So in fact, the video signal travels above the earth's atmosphere twice before we get it in London, but the video delay is only a couple of seconds. That means the conversation between Bill and Sunita will be clear and without long silences despite the huge distances between them. There's no video link back to the ISS from the studio so Sunita will only hear Bill's voice. She won't be able to see what's happening in the studio unless she tunes into the live stream on YouTube!
Geek out for a moment and tell us what equipment you'll be using on the back end to make this whole thing work.
NASA has a network of satellite stations around the world which track the ISS as it travels in orbit, which means they can seamlessly downlink the video signal regardless of the position of the ISS around the world. NASA encode the video signal as data, then send that data from Houston by optical fiber closer to the Atlantic Ocean and uplink to a satellite from there, since there's no single satellite which can be seen line-of-sight in both Houston and London. We have a satellite dish on top of the roof of the studio in London, where we downlink and decode the data into video and patch it into the studio's video mixing desk alongside all the video signals from the studio cameras, Google+ Hangouts, pre-recorded clips and graphics. We have a production team bringing together the event and the program is then sent to digital encoding equipment which sends the digital signal to YouTube's live streaming network in High Definition (HD). Anyone who tunes into YouTube Space Lab should be able to receive the event in real time HD directly from this network.
By now, everyone knows that ThinkPads are the only laptop certified for use aboard the ISS. Will any ThinkPads be involved in presenting the live stream and, if so, what specifically will they be used for?
We've been using ThinkPads throughout—to plan and execute the YouTube Space Lab event, including in the configuration of the live streaming and event production. And yes, on top of that, ThinkPads are actually used on the International Space Station! Every ThinkPad undergoes extreme testing to qualify it for flight-approved duties, just like the astronauts using them.
What are you most nervous about going into the live stream: Sunspots? The position of the ISS? Anything?
NASA have an impressive amount of experience and every day they are working to foresee and control any issues which could arise. For YouTube, obviously there are hundreds of pieces of equipment involved, but we've tested all of them and we have backups in case of failures. Whilst we're naturally anxious that everything goes to plan, we're hugely excited to be providing what we hope is a groundbreaking and amazing experience for everyone. Let us know what you think!