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NASA has recently released plans for a new ion thruster capable of propelling spacecraft to the astonishing speed of 90,000 miles per hour (the thruster is named NEXT–an unnecessarily clever acronym which is short for “NASA’s Evolutionary Xenon Thruster”). Reading about the thruster’s blazing speed made me wonder: what exactly is the fastest human-made item ever? The answer was not what I expected—or rather it was exactly what I expected, but it happened a long time ago.

NASA's Helios 2 spaceprobe

NASA’s Helios 2 spaceprobe

To escape Earth’s gravitational pull, an object must already be traveling around 25,000 mph, so ICBMs and orbital space craft are fairly speedy anyway. Interplanetary probes are the fastest objects we humans have crafted, although they tend to obtain their velocity by means of using the gravity wells of planets or the sun to “sling” off at a higher velocity.  In 1976, NASA launched the solar probe Helios 2 to measure electromagnetic radiation emanating from the sun and to calculate solar magnetic fields.  The eccentric orbit of Helios 2 resulted in the craft reaching a top speed of 157,078 miles per hour. If the probe were running along the equator, it could whip around the Earth six and a third times during an episode of “The Bionic Woman” (or whatever other hour-long show was playing in 1976).

We're probing the sun and voting for Carter apparently that's what's happening...

We’re probing the sun and voting for Carter: apparently that’s what’s happening…

Helios 2 has held the record for being the fastest man-made object since I was a toddler, but NASA has finally decided to rise to the challenge (since nobody else apparently has the know-how or the desire to push mankind forward).  Solar Probe Plus is a NASA mission planned for launch in 2018 which features a robot space probe which will travel to the outer corona of the sun (assuming feckless American lawmakers don’t scrap the mission). When the probe is closest to the sun it will be a mere 5.9 million kilometers (3.67 million miles) from the photosphere of the star and it will be traveling at a blistering 432,000 miles per hour.  The insane temperature and radiation which Solar Probe Plus will face at such proximity to the sun will necessitate that the speed demon robot must take shelter behind a carbon fiber reinforced carbon shield as it blasts through the outer corona at a fifteen hundredths the speed of light (it turns out light is still incomprehensibly fast compared to our very fastest things).

An artist's conception of Solar Probe Plus (Credit: JHU/APL)

An artist’s conception of Solar Probe Plus (Credit: JHU/APL)

(Coincidentally, long time readers might wonder why I have abandoned my usual convention of citing measurement values in metric and then following them with U.S. customary measurements in parenthesis. The answer, alas, is laziness.  All of the sources about really fast things use miles per hour and I didn’t feel like converting.  If you are so inclined, you can easily convert to kilometers per hour (or parsecs per second, or whatever) using the internet.  Alternatively, you could write me an angry letter in French.)

An artist's conception of the earthlike world, HD 85512 b (CREDIT: ESO/M. Kornmesser)

Today it was reported that HARPS, (High Accuracy Radial velocity Planet Searcher) a device operated from the European Southern Observatory’s station atop Mount la Silla in the Andes, has discovered 50 new exoplanets (planets which orbit stars other than the sun).  Sixteen of these new planets are “super-earths” rocky planets with a mass from 1 to 10 times that of our planet. One of these newly-discovered planets, HD 85512 b, is estimated to be only three-and-a-half times the mass of the Earth and it seems like it is located at the edge of the habitable zone, the orbital belt around a star where water can exist in liquid form.  This is only the second exoplanet discovered within the habitable zone, the first being Gliese 581 d.  Interestingly HARPS has disproved the existence of Gliese 581 g (which I wrote about last year) as a mathematical phantasm–so um, you might want to take that post with a grain of salt. The planet HD 85512 b orbits a star which is is approximately 35 light years from Earth.

In the eight years since the program has started, HARPS has discovered more than 150 exoplanets. HARPS discovers new planets by means of a mind-boggling technology: a spectrograph of stupendous precision is mounted on a 3.6 meter telescope in order to take painstaking observations of numerous nearby stars over a prolonged period of time.  A computer program then compares the tiny variances in the light emitted by these stars.  Stars with planets orbiting them undergo slight changes of radial velocity as the planets’ gravity tugs lightly at the stellar bodies. These shifts can be measured via Doppler shift and compared against the expected spectrographic signature caused by the stars relative drift toward or away from the observatory. Over many years the computer can thereby model the mass and approximate orbit of planets around stars (considering the math and the precise observations required for such calculations makes my hair stand on end).

Kepler, the NASA exoplanet discovery project uses an entirely different technology which involves measuring changes in brightness caused by the transit of a planet across a star’s glowing face.

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