Written By: Isaiah Hazelwood, Science Staff Writer
Space exploration is difficult: despite half a century of research and development, only 21 people have left low Earth orbit and only a handful more robotic explorers have done the same. Mars, the planet in our solar system which has received the most attention, is still mostly unknown with only 55 robots sent to investigate it, 25 of those probes successfully entering orbit or landing, and technology still far from letting humans visit. However, as the solar system’s motion regularly brings Earth and Mars closer together, new chances to send more robotic explorers and examine the planet in new ways appear. Last month provided one of these windows, and scientists around the world renewed their interest on Mars as the United States landed their rover Perseverance on the planet’s surface, the United Arab Emirates has brought their satellite Hope into orbit, and China coordinated a satellite and lander pair to get both views of the planet.
Perseverance and Ingenuity
The United States’ National Aeronautics and Space Association (NASA) is the leading group in space exploration, with dozens of ongoing projects. Since the 1960s, NASA has launched 25 Mars missions consisting of 15 orbiters, of which 9 successfully entered orbit, and 9 landers, of which all but one successfully landed on the surface intact. NASA previously landed their Curiosity rover in 2012, and for the past 8 years it has examined Gale crater, a possible ancient lakebed. The Perseverance rover, launched from Cape Canaveral, Florida in July 2020, landed on February 18 in Jezero crater, an ancient lake near an ancient river delta. Despite the robots’ visual similarities and similar landing locations, they have very different equipment and goals. While Curiosity investigated the geology of Gale crater and the past environment of Mars, Perseverance is examining Jezero crater for signs of past microbial life, preparing soil samples for recovery in a future mission, and examining new technologies including oxygen generation and powered flight.
NASA used its SkyCrane method, which it previously used with Curiosity, to land Perseverance on Mars safely. Perseverance was launched in a heat shield capsule, which protects it from the 1,300 degrees Celsius temperatures created as it falls through the atmosphere of Mars at 1,500 kilometers per hour. 11 kilometers above the ground, a parachute was deployed to slow the rover’s fall while its onboard Lander Vision System used radar to track the rover’s location and speed to adjust its fall and its destination. Since radio signals from Earth require 11 minutes to travel the vast distance to Mars, the team at NASA cannot direct the rover as it lands, so the Lander Vision System must control the descent and find a good landing site without any human intervention. At two kilometers above ground, the heat shield separated from the powered descent vehicle holding the rover below it. The powered descent vehicle used a set of rockets to carefully hover 60 feet over the previously identified best landing site, where it lowered the rover to the ground on nylon cords before cutting the cords and flying away to crash outside the crater. Thanks to advancements in the powered descent and Lander Vision System, Perseverance had a much more controlled landing which greatly reduced the uncertainty in its landing zone compared to past rovers.
Like the Curiosity rover, Perseverance has a six-wheel base, pole-mounted panoramic camera, and array of scientific tools powered by the waste heat of a piece of radioactive plutonium. However, its other tools are different from those on Curiosity. Its arm carries an Ultraviolet spectrometer and an X-ray spectrometer, which can analyze rocks, identify organic compounds, and perform chemical analyses, and a hollow-core drill which can collect rock samples. The underbelly of the rover contains a system to store up to 42 rock samples, and the rover can package and cache samples on the ground for recovery by another robot in a future mission. To examine below the ground, a radar imager allows measurements of the planet’s underground structure to centimeters of precision without moving a pebble. Besides these tools for measuring martial geology, the rover carries a weather monitoring device which can measure temperature, pressure, wind, and properties of dust in the air.
The Perseverance rover also carries two experimental technologies being tested for the first time on Mars. The first is a new device which can generate oxygen from carbon dioxide in the atmosphere. While extremely energy intensive and able to produce only 10 grams of oxygen per hour, the device offers proof that the proposed system can generate oxygen and provides more preparation for human arrival on Mars. The second is a miniature helicopter named Ingenuity, currently stored in the belly of Perseverance until scientists want to test it later this year. With Mars’ thin atmosphere providing less air to fly in, Ingenuity is very light and has large fast-spinning blades to provide enough force for liftoff. It recharges through solar panels and can theoretically fly for up to 90 seconds on one charge. Due to the distance between Mars and Earth which delays human radio commands, Ingenuity must fly and land completely autonomously.
Despite Perseverance leading the edge of scientific discovery in a distant place, it has many references back to Earth. Its parachute had an unusual pattern of red and white stripes which, when deciphered, gives the motto of NASA’ Jet Propulsion Laboratory (JPL), “Dare Mighty Things.” On the rover’s body, a metal plaque holds an image of the Earth, Mars, and the Sun alongside 3 miniature silicon chips etched with the names of 11 million people who applied for NASA to include their name on the rover. A NASA logo, JPL logo, and U.S. flag are placed on various sides of the rover, and a plate etched with the Rod of Asclepius is hidden on the rover’s left side as a tribute to health care workers amid the COVID-19 pandemic.
The United Arab Emirates (UAE) is a new player in space exploration, having founded their space agency a mere 6 years ago. However, they are rapidly emerging as an important player as their Hope probe entered orbit around Mars on February 9th, making them the 5th space agency to successfully send a robotic investigator to the planet. With future plans to send a robotic explorer to the Moon by 2024 and conduct additional Mars missions, the UAE’s accomplishments in space will likely appear in the news again soon.
The Hope satellite is powered by a pair of extendable solar panels and has a particularly high orbit above Mars. From this high vantage point, it has a better view of Mars overall which suits its goal: monitoring the global climate and weather patterns of Mars. The probe carries an infrared spectrometer, which can measure the lower atmosphere, a visible light and ultraviolet imager, which captures images of Mars and monitors dust storms in the atmosphere, and an ultraviolet spectrometer, which can measure the concentration of specific elements in the atmosphere. Combining these instruments and its unique perspective, the Hope probe has already returned breathtaking images of Mars.
China’s space exploration program gained attention in the last two years for successfully becoming the first nation to land a rover on the far side of the Moon, then launching another lunar explorer which successfully returned 2 kilograms of lunar soil to earth. The Tianwen 1 explorer, which is the nation’s first Mars mission, was named after the ancient Chinese Tianwen by Qu Yuan and translates to “Heavenly Questions.”
The explorer contains both a satellite and a rover, which both entered a temporary orbit on February 24th and will continue to examine the planet from this orbit for 3 months before the rover is released onto Mars’ surface. The orbiter carries an extendable solar panel and a set of cameras and spectrometers to observe Mars’ upper atmosphere, while the rover carries a smaller set of solar panels, a camera and a multi-wavelength spectrometer, ground-penetrating radar to examine below the surface of Mars, and instruments to monitor Mars’ weather and magnetic field. If the explorer successfully lands in the upcoming summer, it will make China the second nation to land a rover on the surface of Mars.