The surface of Earth is about 71 percent water-covered and yet that is only 96.5 percent of all the Earths water. There is water in the air, in rivers, lakes icecaps and glaciers even the ground not to mention inside of us all. So, that water was dropped off by a series of comets right? Wrong! One of the myriad of discoveries the Rosetta Mission and the ESA has offered to us is that Earth’s water did NOT come from comets. The culprits; Just a guess, or rather hypothesis, but maybe asteroids? Good thing we have missions to get that data as well!
How can they know that? Water is water, isn’t it? No. There’s heavy water. Quite simply where ‘regular’ water is two hydrogen atoms and one oxygen atom, the water molecules found in the “dirty snowballs” that in addition to vapors and gases came off of Comet 67P/C-G was one atom hydrogen and one oxygen atom and one atom of deuterium. Deuterium is similar to hydrogen except it offers an extra neutron in its nucleus. (FUNFACT: ok not so fun – Deuterium can be used in nuclear weaponry & nuclear propulsion) In fact, in 1986 the ESA probe Giotto passed by Halley’s Comet and was able to discover that she had twice the heavy water as Earth had ‘regular’ water. Since Hailey’s comet and Comet 67P/C-G hail from the Oort cloud – it is likely we can rule out the Oort cloud as the source of all Earths water but in the case of Comet 67P/C-G it originates from the Kuiper belt. . The Kuiper Belt is a doughnut-shaped ring, extending just beyond the orbit of Neptune from about 30 to 55 AU. NASA’s New Horizons is due to reach Pluto in 2015.
Ok, so then asteroids gave Earth water. Then asteroids must be full of large amounts of water. Actually – no. But they may have once. They are believed to have lost water due to 3.8-4.6 billion years of hanging with the sun.
This is just a sample of the sort of data the ESA has gleaned from a comet and this data was collected prior to Philae landing on it!
So what missions will we or have we had that will be able to tell us more, maybe answer where the water came from? I’ll list just a few as there are way too many. HOWEVER we get more and more data with cooler spacecraft each time!
· NASA in 2016 is to launch a spacecraft (with a robotic arm to collect samples – AWESOME!) to an asteroid. It is called OSIRIS-REx,
· Launched on 18 October 1989, NASA's Galileo spacecraft set a course for Jupiter and its moons. On the way to the Jovian system, Galileo flew past and imaged two asteroids: first, the main-belt asteroid Gaspra in 1991, and then asteroid Ida two years later in 1993. From this flyby Ida was found to have a small satellite, later named Dactyl.
· NASA's Clementine spacecraft was launched on 25 January 1994. After mapping the surface of our Moon, Clementine intended to move on to making scientific observations of near-Earth asteroid Geographos, to explore the asteroid's surface features and physical properties.
· NEAR-Shoemaker was launched on 17 February 1996 by NASA. This spacecraft carried out the first long-term study of an asteroid at close quarters, exploring the mass, structure, geology, composition, and gravity of nearby asteroid Eros.
· On 27 June 1997 NEAR closely flew past asteroid Mathilde, coming within 1212 km of the asteroid's surface. On 14 February 2000, NEAR settled into orbit around its primary target Eros, and touched down on the asteroid's surface in February 2001, transmitting close-up images as it descended.
· On 15 October 1997, the NASA/ESA/ASI Cassini-Huygens mission to Saturn and its moons was launched. On 23 January 2000, while passing through the asteroid belt en route to Saturn, the spacecraft performed a flyby of asteroid Masursky, taking numerous photographs and estimating the asteroid's size.
· NASA's Deep Space 1, launched on 24 October 1998, aimed to test various advanced technologies in space. On 29 July 1999, Deep Space 1 flew by asteroid Braille, coming within just 26 km of its surface and managing to make a large number of observations which have added to our knowledge of asteroids.
· Launched on 7 February 1999, NASA's Stardust mission swung past asteroid Annefrank on 2 November 2002 en route to its primary target, Comet Wild 2, which the spacecraft encountered in January 2004. Samples from Wild 2 were also returned to Earth via a capsule in 2006, making Stardust the first comet sample return mission of its kind.
· Hayabusa, translated as "peregrine falcon", was launched on 9 May 2003 by the Japan Aerospace Exploration Agency (JAXA). The spacecraft, formerly known as Mu Space Engineering Spacecraft C (MUSES-C), headed to asteroid Itokawa, meeting it on 12 September 2005 and studying its physical characteristics and properties. Hayabusa went on to land on the asteroid in November 2005, staying until April 2007 before returning to Earth in June 2010 with samples from Ikotawa's surface.
· Launched on 12 January 2005, Deep Impact was a NASA probe designed to study the composition of Comet Tempel 1. It successfully completed its mission in July 2005 after launching an impactor at the comet's nucleus, producing a cloud of debris and making it the first mission to eject material from a comet's surface. Following this, the Deep Impact probe was repurposed in 2007 to explore more comets and also extrasolar planets under the new combined moniker of EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation).
AND of course;
· ESA's Rosetta was launched on 2 March 2004, beginning a 10-year-long trek towards Comet 67P/Churyumov-Gerasimenko. On its way the spacecraft performed two asteroid flybys: Steins in September 2008, and Lutetia in July 2010.
This is by no means a complete list but it does show that asteroids have answers and we want to get them!
So when next you drink that glass of water wonder about where in the universe it came from!!