14 DAY TRIAL // With the recent flurry of activity focused on Mars, I could not stop wondering about why other planets in the solar system are not receiving the same amount of attention the Red Planet does. There are 6 other planets besides Mars and Earth, and only some of them have been explored at all so far.
While the Red Planet boasts 5 missions, with 2 underway and 3 more planned, Mercury and Venus are being investigated by single spacecraft, NASA's MESSENGER and ESA's Venus Express, respectively. Jupiter has the Juno probe on the way, and Cassini has been doing a good job at Saturn for a long time.
But what of the two ice giants in the solar system, Uranus and Neptune. Thus far, these planets have only been glimpsed at, thanks to flybys conducted by the Voyager probes. The reason why these worlds are inaccessible is that they are extremely far away, requiring huge spacecraft speeds to reach.
This also implies the use of massive amounts of energy to decelerate any explorer vehicle to the point where it can be captured by their gravitational pulls. Uranus, for example, lies 20 times farther away from the Sun than the Earth does, while Neptune rotates around the star once every 165 years.