The Crestone Eagle • March, 2021
Skies Over Crestone: March 2021
March 1: This is the season for spotting the zodiacal light, which will be visible in our dark skies above the western horizon after sunset. It will be a faint pyramid of light extending up to Taurus and Gemini. It looks like the Milky Way, but as you can check for yourself, it definitely is not the same. The Zodiacal light is produced by sunlight scattered off of dust particles floating in a flat disk between us and the sun. These particles are produced by asteroids colliding with each other, and it is our sun’s version of the rings of Saturn. It should be visible for the next two weeks.
March 2: Look for Mars passing close to the Seven Sisters of the Pleiades
March 14: 2am, start of daylight savings time, whether you like it or not.
March 18: An hour after sunset the moon forms a parallelogram with Aldebaran, Mars and the Pleiades.
March 19: The moon again, an hour after sunset forms a triangle with Aldebaran and Mars.
March 20: Spring Equinox, 3:37am, MDT
Perseverance on Mars
It was a nail-biting 7-minute descent on February 18. Mars has been a graveyard for landers and rovers and about half of the attempts by various countries to land on the surface have failed. Russia has had at least 6 failures. Europe has failed twice. The US is the only country to have successfully placed rovers on the ground, having lost only one rover out of 5 attempts. Perseverance was our most ambitious and dangerous attempt to land a very complicated exploratory vehicle. It is a 2300 lb. automobile-sized laboratory filled with instruments, and many high resolution cameras. It even carried a miniature helicopter on its belly. During its descent its heat shield had to endure temperatures as high as 3,800°F. When it was about 7 miles above the ground, the spacecraft deployed a huge parachute, slowing the heaviest payload in the history of Mars exploration from a speed of 1304mph to about 200mph. Eight retrorockets on the descent stage then fired and Perseverance was lowered gently on three nylon ropes. Once the rover’s wheels touched the ground, the ropes were severed and the descent stage flew away to a safe distance. It was a dazzling success. The engineers and scientists at NASA and JPL erupted with shouts of joy.
The rover’s landing site, Jezero Crater, is a 30 mile-wide impact cater. More than 3.5 billion years ago a river breached the wall of the crater and formed a lake. The large bowl of the crater is also home to one of the best-preserved Martian examples of a delta, a sedimentary structure that forms when rivers enter open bodies of water and deposit rocks, sand and—potentially—organic carbon in layers. Jezero’s fan-shaped delta is one of the prime targets in the hunt for signs of past life. As the flowing water entered the lake it slowed down, and material it carried settled down into the bottom of the lake. Also, like rings around a bathtub, carbonate minerals deposited around the crater’s ancient shoreline. When carbonates precipitate out of water, they can trap things that are in it, including evidence of life.
One of the most innovative features of this mission is the tiny helicopter known as ingenuity, a 4lb helicopter that will hopefully demonstrate powered flight in the thin atmosphere of Mars. The Red Planet’s gravity is about one-third that of Earth’s, but its atmosphere is just 1% the density of Earth’s, making it harder to generate the lift required to get off the ground. When it is first powered up will be another nail-biter. It is equipped with two counter-rotating carbon fiber blades, each 4 feet long, moving at 2500 rpm. It can take color images with a 13-megapixel camera, the same type commonly found in smartphones, and can explore the area much faster than the rover. The low temperatures on Mars may be another problem. Nights on Mars can reach temperatures as cold as that at the South Pole, minus 130°F, and there has been fear that parts of the helicopter could seize-up in that temperature. Ingenuity’s team on Earth has tested the helicopter at Martian temperatures and believes it should work on Mars.
Nearly fifty years ago in the 1970s, the US placed two biological labs, Viking 1 and 2 on the surface of Mars. Three elaborate biology experiments were designed to look for evidence of life. They discovered unexpected and surprising chemical activity in the Martian soil, but they provided no clear evidence for the presence of living microorganisms in soil near the landing sites. It was a demonstration of the limited abilities of pre-programed robots to carry out exploratory biological experiments. Humans could have done so much better, responding to surprising results with new questions. If living field biologists with proper equipment had been on Mars, the project may have detected evidence of life. Now with more sophisticated experiments, sitting on a former lake, and nearly 50 years of advances in astrobiology, that search may be successful.
But more may be needed, especially if some more unexpected puzzles emerge. Samples of soil and rock need to be studied in terrestrial laboratories with instruments too large and complex to send to Mars. Perseverance will place samples of rock and soil in sealed tubes on the surface to be picked up in the future by another sometime in the next decade. That rover will transfer them to the Mars Ascent Vehicle (MAV). This is all wonderfully similar to the adventures of Matt Damon in the movie The Martian. The MAV blasts the samples into Martian orbit where they are captured by an orbiter, which will then leave Mars and deliver the sample containers to Earth, possibly by 2031. It is a sobering insight into the difficulties of future human missions to Mars. Perhaps we need another John F. Kennedy to turn our dreams of visiting Mars into reality.