Ongoing Explorations

January 12

NASA’s New Horizons mission is scheduled to begin scanning Pluto and its entourage of moons. It will fly past Pluto later in the year.

March

MESSENGER will conclude four years of orbiting Mercury this month. The date will be dictated by spacecraft fuel supplies and other factors.

July 14

New Horizons is scheduled to become the first spacecraft to visit Pluto. The spacecraft, which launched in January 2006, will pass just 6,200 miles (10,000 km) from the dwarf planet, and about twice as far from its largest moon, Charon. Because of the extreme distance, though, it will take months for the craft to transmit all of its readings to Earth.

October 28

The Cassini spacecraft is scheduled to make its closest approach to Saturn’s moon Enceladus in several years today, passing just 30 miles (50 km) above the icy moon. Geysers of liquid water and ice shoot into space from an underground reservoir near the moon’s south pole.

Ongoing

Have we visited all the planets in the solar system?

Yes, space probes have visited all of the eight official planets of the solar system.

Here is a listing of the planet visited, most recent spacecraft, and year of visit (or year the mission ended):

• Mercury — Messenger, currently in orbit
• Venus — Venus Express, currently in orbit
• Mars — Mars Reconnaissance Orbiter, currently in orbit
• Jupiter — Galileo, 1995
• Saturn — Cassini, currently in orbit
• Uranus — Voyager 2, 1986
• Neptune — Voyager 2, 1989

Are there plans to return to the Moon?

President Barack Obama canceled NASA’s effort to return astronauts to the Moon by 2020, so no new American Moon missions are likely. China has indicated an interest in sending its own explorers, known as taikonauts, to the Moon in the next decade or so.

In preparation for future manned exploration, the Space Agency had launched several robotic missions to map potential landing sites, map mineral resources, and hunt for possible water at the lunar poles. Future missions in this effort are likely to be cut as well.

Will we ever visit other stars?

The prospects for interstellar travel are quite daunting, primarily because stars are so incredibly far away. The nearest star lies more than 24 trillion miles away. At the fastest speed our spacecraft currently attain — around 100,000 miles an hour or so — it would take almost 28,000 years to get there. Even at only five percent of the speed of light (an unimaginable engineering feat of almost 34 million miles an hour), the trip would still take almost 82 years, with an equally lengthy return trip.

Our best bet may be to build an enormous colony-type spacecraft capable of sustaining a crew for the decades necessary to reach even the nearest stars. Others believe the distance problem may be avoidable altogether through some exotic twist of physics, such as traveling through a wormhole. While either of these plans might seem unlikely at the present, hope springs eternal among scientists and astronomers. Given adequate time and resources, perhaps an interstellar journey does in fact lie in our future.