Twin Speed Demons: Helios 1 and 2, the Fastest Human-made Objects Ever

In my last post, I talked about the fastest artificial object ever (within Earth's atmosphere): a 900 kilogram steel plate that, thanks to the kinetic energy provided by a nuclear blast, travelled at a speed of at least 66 kilometers per second. That's pretty darn fast.

However, there is one object that has travelled faster, and it is the subject of today's FactRoulette!

On January 15th, 1976, the second of two solar probes was launched from Cape Canaveral, Florida. Helios 2, along with the first probe, Helios 1, was designed to study solar processes (basically measuring output from our sun, monitoring sunspots, that sort of thing). They both were sent into heliocentric orbits (a heliocentric orbit being an orbit around the center of gravity of our solar system: basically, the sun), just inside the orbit of the innermost planet, Mercury. Helios 2 orbits about three million kilometers closer to the sun than Helios 1, and sits only 0.29 AU away from the sun (AU stands for "astronomical unit," and 1 AU is the average distance from Earth to the sun, or 149,597,871 kilometers).

One of the Helios probes undergoes testing before its launch into a heliocentric orbit.

In its slightly-closer orbit around our sun, Helios 2 became the fastest artificial object ever, orbiting at an incredible speed of 70.22 kilometers per second.

Interestingly enough, the missions of both probes ended in the early 1980s, but they sent back data to ground computers here on Earth until 1985. They are both currently non-functional, but they still orbit the sun, maintaining their break-neck speed as they circle our star over and over again.



Sources:

Wilkinson, John (2012), New Eyes on the Sun: A Guide to Satellite Images and Amateur Observation, Astronomers' Universe Series, Springer, p. 37
Solar System Exploration: Missions: By Target: Our Solar System: Past: Helios 2


Image:

"Helios - testing" by NASA/Max Planck - http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=10624. Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Helios_-_testing.png