On March 2, Science Daily reported scientists studying the Atlantic Ocean have found an area — thousands of square kilometers in extent — where the planetary crust is missing. By itself, this would be just another fascinating discovery, but that such large features of our ocean’s bottom are not already mapped suggests skewed priorities in publicly funded exploration.

Though oceans cover 71 percent of the Earth’s surface and offer mankind massive environmental and commercial benefits, only 5 percent of the ocean floor has been mapped. Only 10 percent of U.S. territorial waters have been mapped, and only half of that in high resolution. And yet the Moon, Mars and even some moons of Jupiter, which offer humanity value only on the longest time horizons, already have been mapped.

Now consider that NASA’s 2006 budget was $16.5 billion, while the National Oceanic and Atmospheric Administration, which conducts ocean research, had a 2006 budget request of only $3.6 billion. Some scientists have estimated we could map 90 percent of the ocean floor at a resolution of 100 meters over the next 20 years at a total cost of $8million to $16 billion dollars — less than one year of NASA’s budget. That is a mission we should pursue.

We already know we will get environmental benefits: recent small-scale missions have identified many new species, some with entirely novel biochemistries. These organisms offer us an understanding of ecology and evolution unlikely to be gleaned from studying outer space. And think about the advantages for human welfare and prosperity: advances in biotechnology, new mineral resources and new fossil fuel deposits are all likely there for the taking at the bottom of our oceans.

T hen there’s global warming. Wouldn’t it be nice to know if greenhouse gases (or nuclear waste, for that matter) can be efficiently stored on the ocean bottom, or subducted back into the Earth’s crust?

Finally, consider the logistics of exploration and colonization. The high-pressure environment of the deep-oceans is certainly no cake-walk, but it must be easier than the hard vacuum of space. To travel to the bottom of the ocean, gravity takes you where you want to go. No huge, polluting rockets punching holes in the ozone layer or emitting massive amounts of pollution.

If we colonize the ocean floor, we would have water, oxygen and probably food and energy sources waiting on our arrival. An ocean-bottom colony would be safe from virtually any threat to humanity, short of a planet-cracking meteor overhead. Gravity will take supplies down, and buoyancy will take products up. If we need to mount a rescue mission, well, the U.S. Navy has plenty of ships.

Now consider the space program: T he present goal of the U.S. space program is the establishment of a manned Moon-base as a staging point for an eventual manned mission to Mars. What benefits would we derive from such exploration? Environmental benefits?

Other than pretty pictures of the Earth seen from space, the farther we travel from Earth, the less we learn about it. Yes, we can learn about the ocean from orbiting satellites, and we can learn about global warming by studying other planetary climates, but it is a pretty roundabout way of studying the Earth.

Commercial benefits? From what we know, there is little on the Moon or Mars that we do not have in abundance on the Earth, where it is far cheaper to obtain. There would undoubtedly be new technological discoveries as a result of the exploration, but that is true whether we send probes into space, or down into the high-pressure environment of the deep ocean.

What about colonization to give us a Plan B in case of wars, plagues, etc., make Earth uninhabitable? That is s till science fiction — even if water and oxygen can be produced on the Moon or Mars from rock and ice, the technology for producing food and other sustaining goods on site is many decades (if not centuries) away.

W hat if anything goes wrong? We can barely rescue astronauts on the space station, much less the Moon or Mars. And just imagine losing a rocket-load of Mars colonists.

Steven Hawking has argued that humanity needs to get off the Earth in order to gain protection from disasters like wars, pandemics and global warming. Yet the benefits of looking downward are less costly, more immediate and may offer far greater benefits than from looking upward. Before we gallivant into outer space, we should fully explore the inner space of our own oceans. Our national exploration investments and the mission we give our exploratory agencies should reflect that priority.

Captain Kirk can wait.

Kenneth P. Green is a resident scholar with the American Enterprise Institute.