It makes us recall the Apollo Moon landings of 1969-1972. It's hard to place a value on the national pride and prestige that going to the Moon accrued, or the benefit to the soul of such cutting-edge adventure and exploration. No one doubts that we'd all be poorer if people hadn't kicked up the dust on Tranquility.
But what did we learn? Was it worth 24 billion dollars and at least three lives? Granted, the space program brought innovations that found their way into industry and everyday life: things like Velcro and Teflon. And there were computer advances - even if Apollo's computer "Disky" had just 74 kilobytes of memory and four kilobytes of something that sort of resembled RAM.
But the new information didn't increase Earth's food supply, solve our energy problems or increase our life expectancies. Apollo involved discovery, adventure and science of the noblest sort: the kind done for the sheer human yearning to learn and to know. Still, it's natural to ask, "What did Apollo teach us about the Moon?"
The Apollo science harvest is not widely disseminated. NASA was probably remiss in not having in its budget a personable science speaker along with a skilled production crew, whose sole job was to translate the discoveries into Peoplespeak and make them fascinating to the layperson. Then again, maybe most people are simply not that interested in science to begin with.
The dozen most important Moon discoveries:
1. Four centuries of telescopic views from Earth and space probe flybys had convinced astronomers that lunar mountains were pointy and sharp. It's how artists had always depicted the Moon. The lack of lunar air, water, rain, wind - any sort of erosion - supported these observations. But the actual Moon has only rounded mountains, more resembling the Catskills than the Rockies. Turns out that eons of countless small meteor impacts have acted like tiny hammers, pounding everything into a totally worn appearance.
2. Thanks to seismometers planted on the Moon's surface, we learned that whenever the Moon gets a hard impact, the moonquake it produces goes on and on. Moonquakes continue for up to two-and-a-half hours. The Moon rings like a giant gong.
3. The Moon's surface is everywhere covered with fine dust, as smooth as baby powder.
4. The Moon's night and day temperatures are easy to remember. In most places the ground reaches 250 degrees Fahrenheit by day and minus-250° by night. This 500-degree range is much larger than ever seen on Earth, Mars or Venus.
5. Moon rocks are anhydrous, meaning that they contain no water whatsoever. You can't even create water using anything you'd find in a Moon rock. The rocks are also devoid of volatiles (alcohol compounds) and organic compounds (those that contain carbon).
6. Moon rocks were all formed from high-heat events. There is no sedimentary rock: nothing formed in layers or by slowly solidifying wet materials as on Earth, such as limestone, sandstone or shale.
7. The lunar soil or regolith covers the surface to a depth of five to 80 feet. Unlike Earth soil, it contains no air spaces. It is mostly oxygen and silicon, SiO2, like a superfine sand.
8. All questions about the Moon's age have been answered. The oldest rocks have the same age as the Earth: 4.6 billion years. The youngest found were 3.2 billion years old, which coincided with the time when volcanic lava flowed most recently.
9. All craters come from meteor impacts.
10. The Moon is utterly lifeless. This had always been assumed; but after Apollo, we knew it for sure.
11. The Moon is leaving us. Thanks to the laser corner cubes left behind at three of the Apollo landing sites, timed pulses from Earth determine the Moon's distance with one-inch accuracy. This shows that the Moon is slowly spiraling away from Earth at the rate of one-and-a-half inches per year.
12. Before landing there, scientists feared that the Moon's surface might either be a thin crust that would collapse under the weight of a spacecraft, or else be a deep, quicksandlike fine powder that a visitor would sink into, to be swallowed up. Both fears proved groundless. The top few inches of powder are as fine as talcum; beneath that the material is so compact, dense and free of air spaces that it can support any amount of weight. The bearing capacity is similar to a few inches of fine beach sand atop a slab of granite.
What do you think? Go back? Or been there, done that, let's move on?