AstroTalk Episode April 6, 2017

New Horizons and Cassini Missions

3:01pm - 3:29pm
On April 17, 2016, the New Horizons spacecraft (NH) will have reached its halfway point on its flight from Pluto, to its next target in the Kuiper Belt, 2014 MU69 (486.19 million miles from Pluto). When NH does reach 2014 NMU69, it will become the most distant world ever explored in our Solar System. NH is actually slowly down slightly due to the gravitational pull of the Sun. It will therefore reach its midpoint in distance 5 days before it reaches its midpoint in time. And, to add more intrigue to this unfolding drama, NH will also be asleep on April 7, before it reaches the midpoint. This will be done to preserve the systems on the spacecraft. The spacedraft will be put in hibernation for 157 days, but it needs the time off. NH would have been "awake" for 1 and 1/2 years, since December 2014. In that time period, NH flew by Pluto, relayed data back to Earth for 16 months, and also studied a dozen other Kuiper Belt Objects (KBOs). The busy little spacecraft has also studied the outer reaches of the heliosphere (the Sun's atmosphere), and the Kuiper Belt's dusty, ionicly charged environment. Another interesting fact: a signal sent between NH and Earth takes 5 hours and 20 minutes (at the speed of light) to travel the 3.5 billion mile distance between Earth and the New Horizons spacecraft. Now, off to Saturn. Cassini is preparing for its Grand Finale at Saturn, where it will dive between Saturn and its rings, then burn up in Saturn's atmosphere. It will actually go through a total of 22 dives before its grand finale. Cassini has been in the Saturn system for 13 years, and since then it has learned much about things like the moon Enceldus, its icy surface, and its sub-surface ocean, and also about the moon Titan, and its liquid methane seas. With the ocean of information it has gained in this 13 years, mission scientists are using all this information to make the final dive very purposeful. During the final plunge, Cassini will sample Saturn`s atmosphere, sample particles from the rings, and relay back to Earth the closest ever pictures of Saturn, its clouds, and its inner rings. The duties that the robotic probe on Cassini will be assinged to undertake will be downloaded to the probe in what is called a sequence, on April 11. Cassini will study the moon Titan one last time, on April 22, then will carry out other experiments, all in anticipation for its grand finale dive on September 15. This will truly be the end of something special, as Cassini has given the scientists at the Jet Propulsion Laboratory (JPL), anc citizen astronomers, more than they could have ever hoped for.