The topic of space exploration has gotten much media attention lately, mainly focused on the uncertain fate of future US manned space efforts in light of the cancellation of NASA's Constellation program in the administration's new budget. After the current flight of the shuttle "Endeavor" and the four remaining shuttle missions this year, the fleet will be retired and transporting astronauts to and from the International Space Station will depend on Russia, or on unproven spacecraft from commercial start-ups like SpaceX and Blue Origin. Yet without diminishing the importance of these concerns for our long-term access to space, yesterday's delayed launch of the Solar Dynamics Observatory satellite deserved more attention than it got. The SDO mission is part of NASA's "Living with a Star" program, which is aimed at expanding our knowledge about how the sun affects life on earth, with implications for energy and our understanding of the environment, including climate change.
It's hard to think of anything we take more for granted than the Sun, yet as the material on the SDO mission website explains, we don't fully understand the variability and internal mechanics of our planet's primary source of light and heat--and thus directly or indirectly of all the energy we use except for that derived from nuclear and geothermal power. Variations in the amount of solar energy the earth receives as a result of the eccentricity of our orbit around it have long been understood to influence long-term climate patterns, including ice ages, while the impact of fluctuations due to variability in the sun's actual output remains more controversial. Climate skeptics have suggested that much of the warming of the last several decades, along with the recent temperature plateau, could be related to the approximately 11-year sunspot cycle. Meanwhile NASA scientists have assessed the impact of solar variability on climate to be significantly less than that from the accumulation of atmospheric greenhouse gases. SDO should improve our understanding of solar variability and its consequences here on earth. (I should mention that observed recent short-term variability of a few Watts per square meter isn't sufficient to have a noticeable effect on the power output of solar panels.)
The more immediate energy concern that SDO should help to clarify is the risk that currently-unpredictable solar activity, including strong solar flares and resulting geomagnetic storms, poses to power grids--smart and otherwise--and communications equipment on earth and in orbit. At the extreme, a solar flare of the magnitude of the Carrington Event of 1859 could disrupt critical energy infrastructure in much the same manner as an Electromagnetic Pulse (EMP) from a high-altitude nuclear explosion. As dependent as we all are on increasingly complex and inter-connected electrical and electronic systems, anything that improves the ability of scientists to forecast a sudden spike in solar radiation could be worth its weight in gold.
NASA's capacity to conduct missions with immediate benefits on earth, such as SDO and the forthcoming Glory mission to measure key aspects of the earth's energy balance, is crucial, but then so is building on the legacy of four decades of manned spaceflight. I have distinctly mixed feelings about the altered priorities in NASA's new budget, though I'm pleased that funding for space as a whole was preserved. The possibility that this shift will spur a vibrant private space industry that could significantly reduce the cost of reaching earth orbit is exciting, because among other things that could make large-scale space solar power practical and affordable. At the same time I worry that we shouldn't cede America's preeminent position in human space exploration at a time when other nations are setting ambitious goals in this arena.