Thousands of shooting stars per hour scraped a yellowed Martian sky last month as a comet blazed through the red planet's atmosphere at 35 miles per second.

Unfortunately, no one was there to experience the spectacular pass of Siding Spring on Oct. 19, and the remote images and data from the close encounter were not nearly so dramatic.

Still, the space agency has learned surprising things from its extremely rare observations of a comet composed of the matter that formed the inner solar system, scientists said Friday.

The comets dust slammed into the upper atmosphere, creating a massive and dense ionospheric layer, and literally changed the chemistry of the upper atmosphere of Mars, said Jim Green, director of the NASA Planetary Science Division.

The agency and its European counterpart used more than a dozen instruments and a suite of telescopes to chronicle Siding Spring's extremely close flyby, when it came within about 87,000 miles of the Martian surface.

But first, they had to make sure their orbiters - Odyssey, Mars Reconnaissance, MAVEN, and the European Space Agencys Mars Express were out of harm's way on the lee side of the comet's passage. Once the menace of hurtling particles subsided, they got to work.

But data took several days to reach Earth.

We were all wondering what we would see, realizing that the comet had faded in intensity, wondering if we would see anything at all; were all leaning into our screens, said astrophysicist Nick Schneider or the University of Colorado, who is in charge of MAVEN's Imaging Ultraviolet Spectrograph.

Amid the routine, background emissions, scientists suddenly saw this booming signal" of ionized magnesium in the atmosphere of Mars. They also detected iron, sodium, potassium, chromium, manganese, nickel and zinc -- the unambiguous signatures of a comet, Schneider said.

By looking at the brightness and extent of the ultraviolet emissions, researchers estimated that "a few tons, of dust covered at least a hemisphere of the planet," said Schneider. "So it was not an isolated impact," he added.

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NASA dazzled, puzzled by comet Siding Spring data