By Robert Thorson

NASA just swept up some pretty expensive dust. The broom they used was a spacecraft aptly named Stardust, which returned to Earth on Jan. 15 after a seven-year journey. One side of the scientists’ broom contains interstellar dust streaming in from the emptiness of space. The other side holds dust from the close encounter with the Wild 2 comet.

I look forward to hearing what the analyses will reveal about cosmic history and the birth of our solar system. But sometimes I wonder if the excitement isn’t more about the sophisticated and flawless engineering challenge rather than the dust itself, however cool their dust might be. It will consist largely of the raw material from which our solar system was created.

Celebrating astro dust as the Holy Grail of planetary science is like celebrating the pigments chosen by the old masters to create their famous paintings. Or like celebrating the flour used to bake a beautiful wedding cake. Stellar dust, paint pigments and wheat flour: All are ingredients whose histories are shorter, less complex and less interesting than the histories of the finished products. Stardust is to earth history what paint is to the Mona Lisa. Raw material.

The timeworn grit that settles in our cars and homes travels around the world on the wind, rivers and waves. It’s recycled into and out of living creatures, the foundations of the Earth and the depths of the sea. It knows what it’s like to be inside an earthworm, to be squeezed into rock and to dissolve in a stream so that an ocean can grow coral.

Theoretically, one finger swipe of dust from my windowsill could contain a shard of ash recycled from the 1883 Krakatoa eruption, a speck of red clay from the deforested Amazon, a fleck of dandruff from an ice-age mammoth and a pollen grain from a bouquet of this year’s funeral flowers.

My kind of dust has been properly seasoned by time. According to biblical teachings, this is the stuff that God used to make Adam, and that Jesus used to make the blind man see. Dust from the ground. The stuff that makes tulips blossom every spring.

I don’t begrudge the space scientists and engineers their fun. I love the cosmic overtones that resonate from the concept of stardust, that Earth is part of something grander and more ancient. I love the fact that my chemistry shares something with Pluto’s chemistry. I love the theories that can explain why the inner planets are rocky and terrestrial, the middle ones are gas giants, and the most distant are icy dwarves.

I can even get excited about the nuclear processes that fuel our sun. But my excitement with NASA’s stardust fades a bit when I realize that the same old stuff has been settling on the moon since it chilled into solid rock and was trampled by the astronauts as if it were soil.

Sure, the dust NASA just collected is more pristine and primordial than the stuff that falls to Earth each day. But that makes it less interesting to me, rather than more interesting.

Consider the first picture of a newborn baby taken at the hospital or birthing center. Does that photograph or an analysis of that human tissue tell us how that personal life will play itself out? No. Consider, hypothetically, a picture of Earth from outer space, taken shortly after its birth about 4,550 million years ago. Does that photo or an analysis of that gathered stardust tell us how Earth and life will co-evolve? No.

Baby pictures aren’t taken to predict what will happen. They’re taken to be looked back upon as the beginning of personal history. So it is with NASA’s stardust, which I’m glad they collected. Its analysis will help us appreciate the beginnings of what turned out to be a wonderfully chaotic and complex planetary history.