Cosmic happenings have been at the top of the news over the last six months. In January we heard about the brightest supernova ever recorded. At its peak the ASASSN-14lh supernova was 20 times brighter than the combined light of all the stars in our galaxy. Also in January researchers at Caltech revealed evidence for a massive (10 times the mass of the Earth) new planet orbiting in a highly elliptical orbit nearly 60 billion miles from the sun. That puts Planet Nine at more than 20 times the distance of the farthest planet Neptune with an orbital period of 10-20,000 years.
Not to be outdone, Pluto, the former ninth planet now relegated to mere dwarf planet status, had its own day in the sun (as it were). On 14 July 2015 the New Horizons probe completed its primary mission. The nine and a half year (the probe was launched on 19 January 2006) three billion mile trek culminated with a near perfect flyby of Pluto at a distance of approximately 7,750 miles from the surface. The high speed flyby produced fantastic pictures of Pluto and the dwarf planet’s largest moon Charon. To preserve power for a later rendezvous with another Kuiper belt object the New Horizons data is streaming to earth at a not so speedy rate of 1 Kilobit (125 Bytes) per second. That means we’ll need to wait 15 months for last of the Pluto mission data to arrive.
Besides the lack of high-speed data, one of the biggest challenges in cosmic exploration is the time and expense required to travel beyond low earth orbit. After the powerful Atlas V rocket lifted New Horizons out of earth’s gravity well, the probe needed to provide all of its own power. For course corrections and attitude control New Horizons relies on 16 chemically driven thrusters. A cylindrical radioisotope thermoelectric generator uses the radioactive decay of plutonium to power the probe’s systems. Combined these two systems make up roughly a fifth of the probe’s mass. That’s the equivalent of needing a 125 gallon gas tank for a small car.
Back to cosmic travel. Many technologies including a variation of Arthur C. Clarke’s Solar sail from the story Sunjammer, are possible replacements. Unfortunately, they’re not ready for prime time yet. In a bit of an ironic twist spacecraft use the gravity of the planets, moons, and the sun as an accelerating slingshot. New Horizons used a gravity assist from Jupiter in 2007 saved almost one third of its chemical fuel. The “detour” also provided scientists with a trove of new information on the Jovian system.
Today’s map
Cosmic journeys comes courtesy of National Geographic. It illustrates the flight paths for all of the space missions. I apologize for the difficulty in reading some details. It’s a little better if you click on the image and magnify it.
As always thanks for reading.
Armen