In my previous post I talked about the magical quality of an orbit: Each time a spacecraft settles into a permanent path around a new object, humanity has taken one more step in venturing off this little blue world of ours and becoming colonizers of the universe. When the Rosetta reached Comet Churyumov-Gerasimenko on August 6 it marked the 11^th celestial body we’ve orbited: Step #11 in the human conquest of space.
No need to dream. It's happening. Going from zero to 11 has taken just under 57 years; the anniversary of Sputnik, the very first orbiter, arrives this weekend. It’s been a remarkable journey from Russia’s pioneering artificial satellite--hardly more than a metal ball with a radio beeper inside--to the European Space Agency’s Rosetta, which is conducting detailed scientific studies of its comet and deploying a lander onto the surface. And yet, as momentous as each of these new orbits has been, many of them are now largely overlooked. At least one is forgotten almost entirely. (I’m thinking about the first spacecraft to orbit the sun. Can you name it? I couldn’t. See below for the answer.) So here is a look back at the 11 robotic emissaries that brought us out of our planetary cocoon, and the new perspectives that they provided. For more about space exploration, past, present, and future, you can follow me on Twitter: @coreyspowellStep 1: Earth. Sputnik kicked off the space race on October 4, 1957. The 184-pound satellite carried no camera, and really no scientific instruments of any kind. But once it proved that a rocket could break free of Earth’s surface, limitless possibilities opened up. Shown below: a Soviet technician does finishing work on the satellite's pressurized aluminum-alloy skin. (Credit: NASA/Asif A. Siddiqi)
Step 2: The sun. Luna 1, launched by the USSR on January 4, 1959, became an unintended orbital trailblazer. As its name indicates, its target was the moon, not the sun. Due to a rocket burn error, Luna 1 missed by about 3,500 miles and kept on going, breaking free of Earth’s gravity and embarking on its own lonely path around the sun--humanity's first visitor into deep space. The version below is a replica displayed at a Soviet Kosmos celebration. (Credit: RIA Novosti)
Step 3: The moon. With the launch of Luna 10 on March 31, 1966, the USSR made it into orbit around the moon, handily beating the Americans. The victory was short-lived, of course, but that triumph did make Luna 10 the first human object sent into orbit (intentionally) around another celestial body. An electronic performance of the "Internationale" was broadcast from the spacecraft to a meeting of the Communist Party, but it later turned out that the transmission was not live, as claimed. In fact it was recorded earlier and doctored when flight engineers discovered that one note was missing from Luna 10's programming. (Credit: NASA/NSSDC)
Step 4: Mars. NASA's Mariner 9 reached Mars on November 14, 1971, the first spacecraft to orbit another planet. You'll notice that this is also where the cool images begin to show up. The results should have been even better; Mariner 9 was paired with Mariner 8, which was supposed to take most of the pictures, but Mariner 8 failed at launch. Mariner 9 arrived during a vast global storm; as the dust cleared, it made the first observations of Olympus Mons, the largest volcano in the solar system. The hastily assembled initial release image (middle) was subsequently reprocessed to draw out more detail (right).
Step 5: Venus. It's the closest planet to Earth, but Venus presents unique challenges because it is covered with unbroken clouds and has an 850-degree F surface under crushing pressures. On October 20, 1975, the Soviet Venera 9 probe finally mastered both parts. An orbiter circled the planet for the first time, while a 3,400-pound submarine-like probe landed on the surface and snapped 180-degree panoramas of the rocky surface, shown at right. The full, planned 360 degrees didn't happen because one lens cap failed to pop off. (Credit: Roscosmos)
Step 6: Jupiter. There was a long dry spell before Galileo settled into orbit around Jupiter on December 7, 1995. That was the notorious "lost decade" of planetary exploration, when NASA's post-Apollo budget crash extended into a serious drought of planetary science funding through the 1980s. Many of Galileo's exciting findings concerned not Jupiter but its moons--especially volcanic Io and ice-covered Europa. But the probe also made unprecedented observations of Jupiter's vast stormy atmosphere, including this false-color view of the Great Red Spot and its surprisingly Earth-like thunderheads (seen in the inset). Other Galileo images captured enormous lightning bursts, apt for the planet named after a god who enjoyed playing with thunderbolts.
Step 7: Eros. The NEAR spacecraft (Near-Earth Asteroid Rendezvous) almost became NEAR-miss when it experienced an engine malfunction in 1998. On Valentine's Day, 2000, the probe made another pass and this time achieved orbit around the asteroid Eros. This is a totally different kind of object than any that had been circled before: a potato-shaped rocky asteroid whose surface gravity is only about 1/2000th that of Earth. No wonder NEAR had a tricky time making contact! The true-color image shows Eros's battered surface, which bears the scars from a giant impact that occurred about a billion years ago. (Credit: NASA/JPL/APL)
Step 8: Saturn. It took a long time for NASA to get Cassini out there, but it was worth the wait. The probe entered orbit around Saturn on July 1, 2004, and is still returning remarkable science on the planet, its rings, and its eclectic family of satellites. Titan, the biggest by far, is the most unusual moon in the solar system; it has a thick hazy atmosphere, hydrocarbon lakes, dynamic weather, and complicated organic chemistry. Below you see one of Cassini's most beautiful images--one of the most iconic views in all of space exploration. The sun is behind Saturn, leaving the planet dark and the rings eerily lit from behind. Faint structures created by circing swarms of dust suddenly pop into view. Now click to enlarge the image. See that faint speck of light just above the left edge of the bright rings? That is Earth, a pale blue dot nearly a billion miles away! (Credit: NASA/JPL/SSI)
Step 9: Mercury. The planet closest to the sun is tough to observe from Earth and tough to visit by spacecraft, too. On March 17, 2011, Messenger assumed orbit and began the first full, global mapping of Mercury. Although it looks superficially like the moon, Mercury is a very different beast on the inside: It has a large iron core, a strong magnetic field, and a complex tectonic history. One thing it doesn't have is much tonality. The pair of images at below right show Mercury in monochrome and color. Not so easy to see the difference, is it? (Credit: NASA/APL/CIW)
Step 10: Vesta. NASA's ion-powered Dawn spacecraft reached the asteroid Vesta on August 14, 2011, the first time ever that humans had achieved two orbital firsts in the same year. Dawn will also be the first craft ever to orbit two different objects, as it is now headed to explore the dwarf planet Ceres. Vesta is unlike any object visited before; it is a basically a leftover protoplanet, a relic from when our solar system as it was forming. All of the others of its kind got swept up and consumed. Vesta alone survives. Below, a false-color Dawn image shows the location of water-bearing minerals on Vesta. The asteroid's whole south pole is missing, carved out by an ancient impact; the resulting shrapnel that continues to fall to Earth as meteorites. (Credit: NASA/JPL-Caltech/UCLA/PSI/MPS/DLR/IDA)
Step 11: Comet Churyumov-Gerasimenko. Having trouble with that mouthful of a name? You can call it C-G, Churry, or just "that comet visited by Rosetta." The European Space Agency's Rosetta craft began orbiting the 2-mile-wide comet on August 6, 2014. Its adventure is only beginning, but already the probe is returning breathtaking images of the comet, along with a wealth of data on its structure and composition. The story will get even better on November 12 when a lander, Philae, will anchor itself and scrutinize the surface. Look carefully at this recent image and you'll see a jet of dust and gas shooting up from the "neck" of the comet. That is the source material of its tail, just now starting to grow. (Credit: ESA/Rosetta/NAVCAM)