Camera that photographed Pluto is a technological masterpiece

Q: Like most amateur astronomers, I was mesmerized by the recent pictures of Pluto sent back by the New Horizons space probe. What surprised me the most was the clarity and obviously sufficient lighting of the planet and its moons. I thought that Pluto only received about 1 percent of the amount of sunlight that we earthlings enjoy. Can you explain?

A: When you send a $700 million spacecraft on a nine-year journey through the harsh conditions of space, you obviously can’t simply screw on a $69.99 point-and-shoot from Walmart to take a few touristy photos.

So meet Ralph, a camera so incredible that it took Lisa Hardaway and her team at Ball Aerospace in Colorado nearly two years to design and build. Paired with Alice, an ultraviolet imaging spectrometer that can analyze a planet’s atmosphere, it not only had to survive a dangerous journey but also deliver photos showing detailed features in unbelievably low light.

As fans of TV’s earliest days probably can guess, the two instruments were named after the Kramdens on Jackie Gleason’s classic, “The Honeymooners.” But instead of “To the moon, Alice!” as a frustrated Ralph would often bellow at his wife, this pair went all the way to Pluto to produce the close-up pictures that began to stun scientists last summer.

It likely was an almost indescribable triumph for the engineers who set out on what may have seemed a mission impossible. The camera had to be lightweight, use little power, withstand the cold and radiation of space and still take images that would blow the faint smudges we have been limited to by even the best telescopes out of the water.

Her team exceeded expectations, Hardaway has said repeatedly. Unlike its namesake TV character, Ralph came in at a svelte 22.7 pounds, below even what NASA imagined. It uses just 6.3 watts of power — about the same as your typical nightlight.

Proving more challenging were the conditions of space, which would grow increasingly colder the farther the craft flew toward its destination. Hardaway realized that the cold would make different materials shrink at different rates, so the camera would have to be fashioned almost entirely from one material.

“We actually built the mirrors and the chassis out of aluminum so that as they shrank, they would shrink together to maintain the same focal length,” she told The Atlantic last summer. “We could do a reasonable test on Earth and still expect the same quality image.”

For the mirrors, Ball sharpened the normally dull metal with diamonds. The lens was one of the few pieces made from glass.

Then came the final constraint: taking photos under extreme lighting conditions. As you note, the side of Pluto facing the sun receives only about 1 percent of the light that we do on Earth. But even more challenging, scientists also wanted to see the other side, which is lit only by sunlight bouncing off its moon Charon. Engineers said this would like taking a picture of Earth using the light from a quarter moon. Not very bright, in other words.

On Earth, you could simply adjust the aperture and f-stop on your camera to try to compensate for the conditions you’re facing. In an older film camera, you could used a faster-speed film.

“We don’t have any of those options,” Hardaway said. “We had to get it so that the detectors could take a minimal amount of photos (light particles) and turn it into an image.”

So along with specially designed mirrors and lenses, the camera was packed with three ultrasensitive black-and-white and four color imagers that could produce those sharp pictures you enjoy so much. These were fed by a magnifying telescope with a resolution more than 10 times more powerful than the human eye.

Put it all together and the New Horizons was able to take and transmit photos with the resolution of about 820 feet per pixel, allowing us to see features as small as half a city block from 3 billion miles away. The craft also produced stereo images to determine surface topography, examined Pluto’s atmosphere and looked for rings and additional moons.

The results, as you have seen, were truly out of this world.

Q: I don’t want to embarrass you, but I still must ask about a question you posed at the recent trivia night for SAVE. You said Mexico City was the first foreign capital invaded by U.S. troops in 1847. We and others argued that it was Tripoli years earlier, but you would not change your mind. Do you still think you were correct?

A: Despite the line from “The Marines’ Hymn” (“to the shores of Tripoli”), yes, I remain semper fi to my decision.

Today, Tripoli is the capital of Libya, but back in the early 19th century during the two wars with the Barbary States, Tripoli was the name of both a major seaport and an entire province in the Ottoman Empire.

In the first Barbary War (1801-1805), President Thomas Jefferson ordered U.S. Navy ships to help blockade the port of Tripoli. This eventually led to attacks on Tripoli’s own fleet and shelling of the city, but I find no evidence we invaded the city. In fact, the only military action in the city seemed to be when Lt. Stephen Decatur had to sneak in and out one night to burn the USS Philadelphia, which had been captured. A later attempt to send in the explosives-packed USS Intrepid to blow up the harbor ended in disaster.

As a result, the turning point came in the spring of 1805 when nine U.S. Marines led a force of 500 mercenaries to seize the Tripolitan city of Derna (not Tripoli). This apparently was the first time the U.S. flag was raised on foreign soil and led to the famous line in “The Marines’ Hymn.” A treaty was signed a month later.

So, barring further proof, that’s my answer and I’m sticking to it.

Today’s trivia

Where is the smallest U.S. national park?

Answer to Sunday’s trivia: During the Cold War, the familiar red star on the Heineken beer label was perceived as communistic, so the Dutch brewer replaced it with a white star in a red border. Caught up in the passion of the times, people didn’t realize that the red star was a symbol of brewers in the Middle Ages and was said to have mystical powers to protect the quality of their beers. Once the silly brouhaha ended, the red star returned.

This story was originally published May 3, 2016 at 2:49 PM with the headline "Camera that photographed Pluto is a technological masterpiece."