Let's look at some doodles celebrating space missions. If you ever search with Google, you may have seen the doodles before. They're drawings and animations celebrating people, events, holidays, inventions and whatnot, incorporating the Google logo in an amusing way.

Cassini
The Cassini-Huygens mission, launched in 1997, has given scientists a lot to celebrate. It was an international project with NASA, the European Space Agency (ESA) and the Italian Space Agency working together. The Cassini spacecraft carried the Huygens lander that went on to land on Saturn's giant moon Titan in 2005. Cassini continued to study the Saturnian system for more than a dozen years.

During Saturn's solstice and equinox, Cassini collected data and photographed the planet, the rings and the moons. But the fuel couldn't last forever, and the mission had to end in 2017. It did so in a spectacular Grand Finale of orbits in which the spacecraft would dive between Saturn and its rings.

On April 26, 2017 a doodle celebrated Cassini's first dive. The animation depicts Cassini as a paparazzo snapping a celebrity. [Doodle by Nate Swinehart] In a series of such orbits Cassini would gather data to help astronomers understand how the rings were formed and maintained, and more about Saturn itself.

The Grand Finale ended when Cassini plunged into Saturn on September 15, 2017.

Juno
Juno is a daredevil, as befits a fiery-tempered Roman goddess who was very good at discerning the infidelities of her husband Jupiter.

A doodle on July 5, 2016 cheered the Juno spacecraft's insertion into Jupiter orbit on that day. Nearing Jupiter, the giant planet's gravity accelerated the probe to around 265,000 km/h (165,000 mph). For a time Juno was the fastest-moving human-made object ever.

Jupiter is not only our biggest planet, but also the most dangerous. It has an intense magnetic field and highly dangerous radiation levels. Previous visitors to Jupiter kept at a fairly safe distance, but Juno needed to get close with instruments protected. So the probe was built with titanium shields and extra protection for the most delicate electronics and solar panels. And the flybys (called perijoves) are designed to minimize the probe's time in the radiation belts.

Although seven previous spacecraft had visited Jupiter, on the first flyby Juno obtained the very first images of Jupiter's north pole. More amazing close-ups of Jupiter have followed.

Philae
Philae was the lander that the European spacecraft Rosetta carried to comet 67P/Churyumov-Gerasimenko. The spacecraft was named for the Egyptian Rosetta stone that was the key to understanding hieroglyphs, and the Philae obelisk helped to refine the translation. The European Space Agency (ESA) hoped that their mission might find a key to understanding the evolution of the Solar System and the origin of life on Earth.

Philae landed on the comet on November 12, 2014. Unfortunately, it failed to attach to the surface and bounced off before its final landing in an unknown place without sunlight to recharge the battery. Philae sent data and pictures back to Rosetta until the battery ran down. Attempts to locate the lander were in vain.

There were a few brief communications from Philae the following year as the comet got closer to the Sun, but it was only in September 2016 that he was located. That was less than a month before the mission ended with Rosetta making a controlled landing onto the comet.

New Horizons
New Horizons set off for Pluto, then still classified as a planet, in 2006. With three billion miles to travel, it was launched on a powerful launch rocket and went straight into an escape trajectory at nearly 59,000 km/h (36,400 mph). Obviously eager to get on with the job, it was the fastest spacecraft ever to leave Earth orbit.

Over nine years later, on July 14, 2015, New Horizons did its flyby of Pluto and its moons. By then Pluto was classified as a dwarf planet and seen as the gateway to the Kuiper Belt. [Doodle by Kevin Laughlin]

The public was fascinated, and scientists were completely bowled over. Everything seemed to surpass their wildest imaginings. Pluto had a strange and varied terrain, signs of geological activity, and features that will keep planetary scientists scratching their heads for years to come. Even its tiny moons are a puzzle, as was the large moon Charon.

After saying good-bye to Pluto, New Horizons headed for another Kuiper Belt Object 2014 MU69 for a flyby at the start of 2019.

Hubble Space Telescope
The Hubble Space Telescope was built by NASA with contributions from ESA, the European Space Agency. Launched into low Earth orbit in 1990, Hubble had got off to a rocky start with a fault in the mirror. Unfortunately, NASA had not tested it properly before launch. Fortunately, it was designed to be serviced by astronauts using the space shuttle. They were able to save Hubble with some adaptive optics, the equivalent of a pair of glasses. Altogether there were five service missions before the space shuttles were scrapped.

The doodle celebrated Hubble's 20th anniversary in 2010.

The space telescope proved to be a superb research tool, as well a great favorite of the public for its memorable images. Located beyond the distorting effects of Earth's atmosphere it produces very high resolution images of distant objects.