Asteroid Braille has a few interesting characteristics. The object has an inclined orbit compared to the rest of the solar system, meaning that it is tilted with respect to most of the other worlds. It also belongs to a Mars orbit-crossing asteroid group. Braille rotates once every 9.5 days and is about 1 to 2 km (0.62 to 1.2 miles) in diameter.
Deep Space 1 took pictures in visual and infrared wavelengths; it passed within just 14 miles (26 kilometers) of Braille, but because of a problem with the tracking system, the pictures were taken from thousands of miles away.
NEXT: Stardust at an Asteroid
NASA's Stardust is most famous for collecting the first sample from a comet and returning it to Earth. The spacecraft launched on Feb. 7, 1999, and flew by asteroid Annefrank on Nov. 2, 2002, before the most famous part of its mission. It is best known for flying by Comet Wild 2 in 2004, picking up comet and interstellar dust. The samples returned to Earth in their own capsule in 2006, while Stardust was repurposed for a new mission called Stardust-NExT. The probe flew by Comet Tempel 1 on Feb. 14, 2011.
NEXT: Asteroid Annefrank
Annefrank is an S-type asteroid that is roughly 2.8 miles (4.5 km) in diameter. Pictures from Stardust showed several impact craters and also suggested that Annefrank may be a loosely linked set of two asteroids, also known as a contact binary. Since Stardust flew by Annefrank, which was named after the famous diary author who was killed in the Holocaust, other observatories have tried to narrow down the asteroid's rotation.
NEXT: Japan's Hayabusa!
Hayabusa (aka, MUSES-C) was a Japanese spacecraft designed to return samples from the near-Earth asteroid 25143 Itokawa. It launched on May 9, 2003, and successfully met up with Itokawa in September 2005. The spacecraft endured multiple malfunctions during the mission but managed to finish most of its major objectives. The spacecraft's samples returned to Earth on June 13, 2010, but it took time for scientists to open its container and check for samples. Hayabusa mission scientists confirmed in November 2010 that Hayabusa indeed picked up samples of Itokawa.
NEXT: Asteroid Itokawa
Itokawa is a potentially hazardous asteroid that periodically crosses Earth's orbit; that's one of the reasons this asteroid was chosen for close-up study. It's about 1,150 feet (350 meters) in diameter and is classified as an S-type asteroid. Images from the spacecraft showed few impact craters, though a "rubble pile" appears on the surface.
NEXT: Europe's Rosetta
Rosetta's Asteroid Encounters
The European Space Agency's Rosetta spacecraft was a popular mission that successfully made its way to a comet and landed a probe, called Philae, on the object's surface. Rosetta launched on March 2, 2004, and made two asteroid flybys before its last destination: 2867 Steins (September 2008) and 21 Lutetia (July 2010).
Rosetta successfully reached Comet 67P/Churyumov-Gerasimenko on Aug. 6, 2014. The probe released Philae a few weeks afterward; the lander bounced on the surface before settling in a shady spot. Philae quickly ran down its batteries but still performed some science before losing power. Rosetta landed on the comet on Sept. 30, 2016 to end its mission.
NEXT: Asteroid Steins
When Rosetta reached Steins, the probe discovered that the object is a rare E-type (enstatite) asteroid, meaning that it has iron-poor silicates on its surface. The asteroid is roughly 4.1 miles (6.6 km) at its longest dimension and is likely part of a larger object that broke apart. Rosetta spotted impact craters on Steins' surface, and the space rock's measurements suggest that the interior consists of rubble. The asteroid will likely disintegrate due to its delicate interior.
NEXT: Asteroid Lutetia
Lutetia is another crater-pocked asteroid. Rosetta found that the asteroid is about 80 miles (130 km) at its longest dimension. Its composition is a little unclear, with characteristics of both C-type and M-type asteroids. The European Space Agency described the asteroid as "most probably a primitive survivor from the violent birth of the solar system."
NEXT: Spacecraft Dawn
NASA's Dawn Rises
NASA's Dawn mission launched on Sept. 27, 2007, to investigate two large members of the asteroid belt: Ceres (a dwarf planet) and 4 Vesta (an asteroid). First, the spacecraft came to Vesta, orbiting the planet between July 2011 and December 2012. Dawn's next and final destination was Ceres, where it entered orbit on March 6, 2015. The mission is expected to continue until late 2018, when the probe's hydrazine fuel will run out. (NASA also considered sending Dawn to visit a third target but ultimately turned down the idea.)
NEXT: Asteroid Vesta
Dawn arrived at Vesta on July 16, 2011. Vesta is roughly 330 miles (530 km) in diameter, and notably, the asteroid's surface has a huge crater, Rheasilvia, that makes up 95 percent of that diameter. The impactor that hit Vesta probably caused a mass loss of 1 percent when it slammed into the asteroid, creating the a family of smaller space rocks out of the debris. Vesta is also known for its variations in brightness, with some of the darker rocks believed to be deposits from other asteroids hitting Vesta.
NEXT: Asteroid Ceres