Editor’s note: A version of this has been previously published on the author’s website.
For a quiescent planet, Mars certainly has been grabbing the headlines lately.
Two orbiters, two landers and a helicopter approach
On Oct. 27, NASA announced the rover Perseverance and its small helicopter Ingenuity had reached the halfway point on a curving trajectory toward landing at the Martian Jezero Crater. At that time they had traveled 146.3 million miles since the July 30 launch. Also in July, the United Arab Emirates and China shot probes toward the fourth rock from the Sun.
The UAE’s (Hope) is to study Mars’ upper atmosphere and look for climate change from orbit while the Chinese project, Tianwen-1 (Questions to Heaven), includes an orbiter and a lander that will search for water ice, report Arab News and the Xinhua News Agency, respectively.
America’s efforts are the most ambitious of the three countries. The helicopter Ingenuity is an experimental aircraft intended as a technology demonstration, and will not carry out scientific research on Mars. According to NASA, it is “to test — for the first time ever — powered flight in the thin Martian air,” independent of Perseverance. On the ground, the rover will be “searching for signs of ancient life and collecting samples of rock and sediment in tubes for potential return to Earth,” the agency adds. If Ingenuity succeeds, future Mars landers may use little ’copters in their surveys.
The reason for launching robotic explorers this year is that the orbits of Earth and Mars brought the planets into an alignment that allows a relatively quick trip — seven months for the American craft.
Every 26 months, Mars and Earth line up with the sun in what is called an opposition. The word may seem to imply the planets are on opposite sides of the sun but it doesn’t; it means the sun and Mars are on opposite sides of the Earth in the order Sol, Earth, Mars. While not as spectacular as the Mars opposition of 2003, the one on Oct. 13 was great. Mars “will not be this big and bright again for 15 years,” said astronomers of Lowell Observatory, located on Mars Hill near Flagstaff, Arizona.
What made it outstanding was that the nearest the two planets drew to one another in their orbits happened on Oct. 6, a week before opposition. Mars was especially bright in the sky because the sun shone directly on it from our perspective, and it was larger than usual because of the close approach, as National Public Radio noted.
AI locates small features
A groundbreaking study of the Martian surface made news worldwide on Oct. 4 when the site earthsky.org carried an article about a new way to detect tiny craters using artificial intelligence. The article was written by Amy Oliver, who is a member of the Utah Astronomy Club, the visitor and science center manager at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and the public affairs officer of the Harvard-Smithsonian Center for Astrophysics. A Utah native, Oliver is a NASA solar system ambassador for Utah and Arizona.
She wrote that for years NASA scientists had been combing slowly through photos taken by the Mars Reconnaissance Orbiter, looking for tiny features of the landscape — a process that ate research time at up to 40 minutes per photo. Now the task is assisted by an artificial intelligence program, “an automated fresh-impact crater analyzer,” used by scientists at the Jet Propulsion Laboratory in Pasadena, California. It can analyze a photo in about five seconds and flag small items that otherwise might be overlooked.
The program’s discoveries have been verified by follow-up images. But the analyzer doesn’t have all the observation skills of a scientists, the article says, quoting Ingrid Dubar of JPL and Brown University, in Providence, Rhode Island. The results are double-checked against high-resolution images of the same sites.
The view from Earth
During the opposition period throughout October and into November, Mars has attracted presumably millions of humanoid eyes. Its position high in a dark section of the constellation Pisces also provides a rare opportunity for amateur astrophotographers. Ordinarily the planet is so small and dim as to present poor opportunities, but this opposition was an exception. It has been big and bright.
Between Oct. 4 and Nov. 1, I spent much of 10 nights with a telescope in the backyard of my Salt Lake City home, trying to get pictures of the orangish dot.
Most of my pictures were duds. Mars shone so fiercely that first attempts with my sensitive astronomical camera produced glaring, overexposed photos, just white disks in the black. Even shooting at the camera’s fastest speed of 1/1000 of a second, the planet was blank.
Next, I taped a cardboard mask over the end of the telescope (the lens called a “corrector plate”), which reduced the ‘scope’s effective diameter from 12 inches to about three. It cut down the light enough to get views but I regretted I couldn’t use the full aperture, which would have given better detail.
Later, to use the telescope’s full diameter, I hooked on an old Nikon D70 camera whose light sensitivity is adjustable. I tried three different configurations but none was satisfactory with Mars.
Meanwhile, some astonishing views were made by other Utah amateurs. A notable example was taken by Don J. Colton of the Utah Astronomy Club that picked out the solar system’s largest volcano, Olympus Mons, and three smaller volcanoes nearby.
The best of my Mars photos were downloaded into a laptop the night of Oct. 18-19, taken with the astronomical camera when most of the telescope’s opening was blocked against the glare.
The resulting picture is a stack of the best of 300 subexposures taken between 1 and 2 a.m. on Oct. 19; in Universal Coordinated Time, that translates to 7 to 8 a.m. on Oct. 19 UTC. The exact time is important because a Mars Profiler posted by Sky & Telescope Magazine allows one to identify features as they show up on the rotating planet at precise times.
The south pole, largely carbon dioxide ice, is the bright spot at the bottom of my picture around the 7 o’clock position — the pole is tilted relative to our viewpoint.
In 2004, the European Space Agency announced that water ice is present as well as frozen CO2 at the southernmost region. Readings from ESA’s Mars Express, Europe’s first spacecraft to orbit Mars, “showed that hundreds of square kilometres of ‘permafrost’ surround the south pole. Permafrost is water ice, mixed into the soil of Mars, and frozen to the hardness of solid rock by the low Martian temperature,” said ESA. “This is the reason why water ice has been hidden from detection until now — because the soil with which it is mixed cannot reflect light easily and so it appears dark.”
What look like continents are differences in surface brightness — often caused by features such as upthrusts, canyons and rough terrain. Astronomers have mapped and named dozens over the centuries.
In my photo, the dark mark that projects northward prominently on the left is called Syrtis Major, described by the Encyclopedia Britannica as extending north from the equator for 930 miles and reaching 620 miles west to east. “It is an extensive regional slope elongated north to south that drops 2.5 miles from its western boundary (Aeria) to its eastern edge (Isidis),” the encyclopedia adds.
Blending with Sytris Major on its right along the equator is a form termed Mare Tyrrhenum, part of an area that is mostly “heavily cratered highlands,” says marspedia.org. The dark elongated figure to its right, reaching to the right edge of the planet, is named Mare Cimmerium. Mare means sea, and like the marie on the Moon, those of Mars are bone dry.
To the south of Sytris Major and Tyrrhenum is a vast impact basin called Hellas (the ancient name for Greece). “With a diameter of about 1,400 miles and a depth reaching the lowest elevations on Mars, Hellas is one of the largest impact craters in the solar system,” says NASA. The light oval within Hellas, visible in my photo by the planet’s edge at 9 o’clock , is the Hellas Plane.
For me, the thrill was in taking pictures of recognizable landforms on a planet 40 million miles away.
Joe Bauman, a former Deseret News science reporter, writes an astronomy blog at the-nightly-news.com and is an avid amateur astronomer. His email is firstname.lastname@example.org.