The discovery of liquid water percolating across the surface of Mars puts an exclamation point on what scientists have been finding during the last couple of decades: the solar system is wet. Very wet.
This has important implications for two of NASA’s most important missions: human exploration and the search for life. Here’s how:
When the Apollo astronauts landed on the moon in the late 1960s and early 1970s they found a dry, gray surface. However since then probes sent to the surface of the moon have found “significant” amounts of water locked away in the moon’s soil.
Over the eons comets striking the moon have deposited as much as 10 billion tons of water at the poles, roughly the volume of Utah’s Great Salt Lake. That’s enough fuel to launch the equivalent of a space shuttle, every day, for more than 2,000 years.
The presence of water on the moon is a potential game-changer for human exploration of the solar system. Astronauts can drink it, of course. It also could shield their habitats from radiation. Broken apart, water provides breathable oxygen and hydrogen for fuel cells. But above all else for nations seeking to explore far from home, the water is a tempting cache of fuel. Oxygen and hydrogen are the most powerful rocket fuels known to man.
NASA, working with private companies, could use the moon and its fuel as a staging point for human exploration into the solar system, because potentially it’s a lot cheaper to fill up at the moon, rather than launching all of your fuel from the Earth’s surface.
Many people in the space industry want to develop these lunar resources before sending humans further into the solar system, saying it provides a more sustainable path for exploration.
In recent decades scientists have been steadily revising their assessment of Mars as a cold, dry and dead world.
They have found ice at the poles and, increasingly, beneath the surface at more temperate areas of the planet. Now, with the news this week, there is evidence of periodic small flows of very salty water on the surface.
“All of the scientific discoveries we’re making on Mars are giving us a much better view that Mars has resources that are useful to future travelers,” said John Grunsfeld, NASA’s chief of scientific missions. “The water really is crucial.”
Like on the moon, the presence of water beneath the surface could allow astronauts to make their own rocket fuel to return home to Earth.
Unlike on the moon, the possibility of aquifers beneath the surface of Mars increases the likelihood of microbial life existing there today. The increases the urgency to explore this world for life.
The bottom line is that Mars sits at the sweet spot for NASA. It is not only an inviting target for human exploration — indeed it is the furthest we can reasonably expect humans to travel within the next 50 to 100 years — Mars also could harbor life today.
Many planetary scientists now believe Jupiter’s moon Europa is the most likely place, aside from Earth, for life to exist in the solar system.
Europa harbors vast oceans beneath its ice sheets, more water than exists on Earth. The average depth of the Pacific Ocean is about 2 miles. On Europa the oceans are up to 60 miles deep. At the inky bottom of Earth’s oceans, near volcanically active areas, life teems around hydrothermal vents. Scientists believe similar features line the bottom of Europa’s ocean.
Now NASA is planning a fly-by mission to Europa that will launch early in the 2020s. And while it’s not talking publicly about it, that mission is also very likely to include a lander that will probe the moon’s icy surface.
Further out in the solar system, Enceladus is a tiny moon of Saturn. It is notable for geysers of water at its pole.
Earlier this year scientists found evidence of a global ocean on Enceladus under an icy crust.
Although smaller than Europa, Titan offers another promising location for life to exist with water and, near its core, a source of heat.
Further out still, around Neptune, geysers on the moon Triton spew nitrogen gas into space.
This indicates the moon is volcanically active and has enough internal heat to sustain a subsurface ocean. But does one exist? We don’t know as Triton has only been visited by Voyager 2 way back in 1989.
Nevertheless there’s definitely interest among scientists in exploring this world further.
Ok, so we’re not going to find life on Pluto. And it’s difficult to imagine humans visiting the small planet during the next century, or beyond.
But come on, New Horizons found ICE MOUNTAINS on Pluto. As in mountains made out of ice.
How cool is that?
While it won’t facilitate exploration any time soon, the stunning diversity of terrain on Pluto is sure to inspire the next generation of explorers.