Friday July 20 marked the 43rd anniversary of Apollo 11’s landing on the Moon. Certainly one of the milestones of human accomplishment, the 250,000 mile trip to the Moon marks the furthest humans have traveled, in person, from our home planet. This December 15th will mark the 40th anniversary of the Apollo 17 astronauts leaving the Moon’s surface, the last time humans placed a footprint in the lunar regolith. I have to admit a feeling of sadness that this high-water mark of human achievement occurred so long ago and that the outlook for us returning to the moon, or going farther, in the next 20 years requires a willingness to invest in that mission that I am not sure we have in the United States today.

While human exploration naturally excites the passions of the poet and pirate in each of us, the scientist in me realizes that robotic space missions are very cost effective and have made possible some incredible discoveries. NASA continues to do cutting-edge science and make breathtaking achievements despite the end of the Apollo and Space Shuttle eras. Last month NASA announced that Voyager I and II (11 and 9 billion miles from the Earth respectively) are beginning to sense a change in the amount and type of radiation in the region of space they are entering. This change indicates the spacecrafts are approaching the boundary that demarcates the region protected by the Sun’s magnetic field – the heliosphere and interstellar space. The exact location of the edge of the solar system is an important finding and a fitting conclusion to the careers of two robotic spacecraft that visited the outer, gas-giant planets and their moons. Voyager I and II returned some of the most memorable astronomical images in the decade before the Hubble Space Telescope. Some examples, shown to the right, are images capturing an erupting volcano on Jupiter’s moon Io and revealing the tantalizing cantaloupe-like terrain of Neptune’s moon Triton.

Launched last November, the aptly-named Curiosity rover is due to land on Mars around 1:30am EDT on August 6th. The Spirit and Opportunity rovers explored Mars for over 7 years. While Spirit is no longer operational, Opportunity continues to travel across the Martian surface. Considering that engineers determined their expected operational lifetime to be three months, their longevity has been an accomplishment in itself. Now, a much larger rover will be landing next month. The one-ton curiosity rover cannot come to bouncing halt on the surface like previous rovers. Instead, NASA engineers designed a “sky-crane” method for dropping the rover from a rocket-propelled platform. This video gives an excellent visualization of the challenges the rover will face during its 7 minute decent. If all goes as planned, for the next Martian year (approximately two Earth years), Curiosity will be exploring the bottom of Gales crater analyzing soil and rocks there to determine if the Martian surface could have supported life in the past. Unlike previous solar-powered rovers, Curiosity is nuclear-powered which will allow for a more robust and reliable power – dust and the Martian winters would often limit the amount of power the earlier rovers could generate.

NASA continues space exploration with increasingly sophisticated robots making the long and dangerous treks between and beyond planets. At the same time, Virgin Galactic is booking sub-orbital flights for space tourists (over 500 have made deposits) and building a spaceport in New Mexico. Their innovative launcher and rocket, shown to the left, look very promising and are environmentally more sustainable than previous launch vehicles. In May, SpaceX  made history successfully launching and docking the first commercial vehicle to the International Space Station. The reusable Dragon spacecraft is shown attached to the ISS in the image to the right. So, there are a number of reasons to be excited about the future of space exploration even if it has been 40 years since humans last walked on the Moon.