The 1980s brought about an existential crisis for U.S. planetary exploration. As we see above, NASA’s planetary science budget was cut to the bone and the entire enterprise was nearly abandoned. NASA was able to develop and launch the Galileo spacecraft in the 1980s, demonstrating that large projects may be viable even at historically low funding levels, but Galileo faced a tremendous amount of budgetary adversity. And like a snake that swallowed a goat, the planetary science community had to wait for Galileo to pass through before new missions could begin. In fact, NASA launched only one other planetary science mission in the 1980s (Magellan), resulting in a “lost decade” of planetary exploration. The volume of talent and capability abandoned to attrition during this time is difficult to measure. Planetary science made up 32 percent of a depleted space science budget in this lost decade, but just three percent of a historically low NASA budget, reflecting the priority NASA leadership and lawmakers placed on scientific exploration of the solar system.

By the second half of the 1990s, planetary science experienced a moderate increase in funding, resulting in an increased flight rate for new missions. A new generation of space enthusiasts marveled at the first photographs from Mars in more than a decade as NASA distributed video from the Mars Pathfinder’s rover Sojourner over an increasingly popular internet. Pathfinder was the first mission of the incredibly successful Discovery program, focused on small planetary missions. NASA also launched the flagship mission Cassini, which became the first spacecraft to orbit Saturn and is still operating today. During the 1990s, planetary science represented 33 percent of the space science budget, and 4 ½ percent of NASA’s total budget.

While many have referred to the ‘60s and ‘70s as the “Golden Age” of planetary exploration, I think a case could be made that the real golden age began in the first decade of this century. Looking again at the plot above, we see that NASA’s planetary science budget hit its highest level historically in 2005, and the list of successful missions since then is impressive. A fleet of spacecraft went to Mars to orbit, land, and rove on the planet, providing an unparalleled scientific return. MESSENGER became the first spacecraft to orbit Mercury, and New Horizons, launched in 2006, will arrive at Pluto next year, the first spacecraft to visit the dwarf planet. From 2000 to 2009, NASA’s Planetary Science Division received 34 percent of the agency’s increasing space science budget and nine percent of NASA’s total budget.

So clearly, prioritization (as demonstrated by funding) has real consequences. And more, there seems to be a floor to the level of funding we can allocate to planetary science and still maintain a viable program (the early 1980s). By contrast, we have seen the effects of a moderate prioritization (the 1990s) and a higher prioritization (the mid-2000s). In my next post I hope to dig a bit deeper into just what we get for our investment in planetary science.