Pluto in a Minute: Why Is It Taking So Long to Downlink Data from New Horizons? скачать в хорошем качестве

Pluto in a Minute: Why Is It Taking So Long to Downlink Data from New Horizons?

You know how we keep saying there's more data to come from New Horizons? This is why. And this is Pluto in a Minute. So part of the problem is that the spacecraft has a limited amount of power on board because of its battery. The spacecraft can generate about 200 watts but that's to power all the instruments. But the team has to specify which instruments are running when. When the spacecraft is taking minimal measurements, it actually goes into what's called a spin stabilization. The spacecraft is spinning so it's not actively using its gyros or its reaction controls to orient itself. But just because the instruments aren't actively taking data doesn't mean the transmitter gets more power. It just means that, because fewer systems are working, the transmitter is able to be on. So when the spacecraft is spinning it can actually achieve higher data rates of between 1,000 and 4,000 bits per second. But there are 50 gigabits of data on the spacecraft! So! Let's break down how long it's going to take to get all that back! Give its antenna size and limited by its power source, New Horizons can download seven megabits of data per hour. Each downlink is about an eight hour pass because of the rotation of the Earth, so that's 58 megabits in each pass, which amount to about 173 megabits every day. With 50,000 megabits on board downloading 173 megabits a day, and we don't have exclusive access to the deep space network, that takes about 500 days to get all the data from New Horizons back to Earth. For more news on Pluto check out the New Horizons websites, join the conversation online with the hashtag #PlutoFlyby, and keep coming back here for more Pluto in a Minute. http://www.nasa.gov/newhorizons http://pluto.jhuapl.edu