The Mariner 4 probe was launched in 1964 and traveled toward Mars. It was the first satellite to take up close pictures of another planet.
Credit: NASA

On Earth, the blue and green planet of our solar system, we are celebrating Red Planet Day today, November 28. The red planet is a nickname for Mars, the fourth planet from the sun. On November 28, 1964, NASA launched the first mission toward Mars, with the Mariner 4 probe. We call it “the Red Planet” because the surface of Mars has a reddish color due to the weathered iron-rich minerals present in the Martian dust and surface rocks. The iron oxidizes creating rust. We should call it the rusty planet! Many ancient peoples associated the planet with war and conflict because of its blood-red appearance. Indeed, Mars is the Latin name for the ancient Roman god of war.

Mars, like Earth, has clouds in its atmosphere and deposits of ice at its poles. But unlike Earth, Mars has little to no liquid water on its surface. The rustlike color of Mars comes from the large amount of iron in the planet’s soil.
Credit: NASA/JPL/Malin Space Science Systems

Humans have been studying Mars for centuries. Visible from Earth with the unaided eye, Mars has always captivated us! Of all the planets in our solar system, Mars has the surface environment that most closely resembles that of Earth. Mars has weather and seasons and landforms that appear familiar. Salty water may flow just below the planet’s surface. Like Earth, the sun, and the rest of the solar system, Mars is about 4.6 billion years old.

Mars has a special place in popular culture, one that is unique among the planets. This fascination with Mars probably developed because the planet is relatively close to and similar to Earth. Early observations with Earth-based telescopes inspired popular speculation that Mars was home to all kinds of life, even alien civilizations. Many works of science fiction have played upon these ideas, showing humans visiting Mars or malevolent Martians invading Earth.

A Martian landscape includes jagged rocks, sand dunes, and hazy clouds. The image, taken by the United States rover Curiosity, has been adjusted to show the natural color of the planet, as it would appear to an observer on the surface.
Credit: NASA/JPL-Caltech/MSSS

In the 1960’s, the U.S. Mariner spacecraft showed Mars to be a cold, desert planet devoid of visible life. But Mars continues to fascinate people with hints of past surface water and the possibility that microscopic life once existed or still exists there. Experts also view Mars as the next likely target for human space exploration and perhaps even as a stepping stone to exploring the rest of the solar system.

Robotic spacecraft began detailed observation of Mars in the 1960′s. The United States launched to Mars the Mariner 4 probe in 1964 and Mariners 6 and 7 in 1969. The pictures they returned showed a barren surface, covered with craters like those on the moon. There was no sign of liquid water or life. The spacecraft observed few of the planet’s most interesting features because they happened to fly by only heavily cratered regions. But when Mariner 9 went into orbit around Mars in 1971, people’s view of Mars completely changed. Mariner 9 mapped about 80 percent of Mars and made the first discoveries of the planet’s canyons and volcanoes. It also found the first evidence for water, taking photographs of the outflow channels and valley networks.

The Parker Solar Probe approaches the sun in this artist’s depiction. The probe’s path takes it nearer to the sun than any other human-made object, allowing it to make close-up observations of solar activity.
NASA

The Parker Solar Probe has done the unthinkable. It became the first spacecraft to touch the sun! Scientists reported the announcement on Dec. 14, 2021, at the press conference at the 2021 American Geophysical Union Fall Meeting in New Orleans, Louisiana. The probe was built and operated by the Johns Hopkins Applied Physics Laboratory. The probe flew through the upper atmosphere of the sun, called the corona, to collect samples. The samples will allow scientists to understand more about the sun, just like landing on the moon paved the way for scientists to learn about the moon.

The National Aeronautics and Space Administration (NASA) launched the Parker Solar Probe in 2018. The probe completed its first orbit of the sun in 2019. The probe is the fastest human-made object in the solar system. The sun’s gravity is expected to accelerate the probe to extreme speeds of up to 430,000 miles (700,000 kilometers) per hour. Three years after the launch, the probe has arrived at the sun.

The goals of the mission are 1) to study how energy and heat flow through the corona; 2) to gather information on plasma (the gaslike substance the sun is composed of) and magnetic fields near the sun; and 3) to learn more about how high-energy particles travel outward from the sun.

It uses a set of instruments known as FIELDS, which has antennas to measure electric fields and magnetometers to measure magnetic fields. The probe is also equipped with a pair of cameras to capture images of the sun. The probe carries various instruments for studying particles in the solar wind—that is, the continuous flow of particles from the sun.

The sun’s corona can be as hot as 4,000,000 °F (2,200,000 °C). Because of the corona’s low density (concentration of matter), the Parker Solar Probe will not experience the sun’s most intense heat. However, it will encounter temperatures of up to 2,500 °F (1,377 °C)—hotter than lava from a volcano.

The Parker probe is planned to approach the sun 24 times by the mission’s end. Hopefully, the Parker probe can stand the heat and gather more information about the corona and solar winds.

June 7, 2018

Last month, on May 5, the United States National Aeronautics and Space Administration (NASA) launched a new Mars probe called Insight from Vandenberg Air Force Base in California. InSight is short for Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport. InSight, a probe that will study the formation of Mars, is NASA’s first interplanetary mission launched from the west coast of the United States. All previous such launches took place at Cape Canaveral Air Force Station in Florida.

This artist’s rendition shows the InSight lander operating on the surface of Mars. The probe is scheduled to land on Mars on Nov. 26, 2018. Credit: NASA/JPL-Caltech

The InSight mission cost just $814 million, a relatively small sum in the multibillion-dollar science of space exploration. The bargain probe will break new ground, however, quite literally, by drilling into the Martian surface. It will sample temperatures, measure the magnetic field, and record seismic levels, all to help scientists understand the planet’s formation. The data may also shed light on the formation of Earth and our solar system.

A NASA Atlas V rocket carrying InSight breaks through the clouds above Vandenberg Air Force Base in California on May 5, 2018. Credit: Cory Huston, NASA

Earth has three major layers: the crust, the mantle, and the core. Planetary scientists think our solar system’s other rocky planets—Mercury, Venus, and Mars—also have these layers. Scientists are unsure, however, how thick the layers are in the other planets. Earth has churned itself up through the process of plate tectonics, changing the chemical makeup and size of its layers over time. But Mars, the fourth planet from the sun, has experienced much less seismic activity. The planet’s present structure, then, should somewhat resemble its original composition when the solar system was formed.

Beginning in late November 2018, NASA’s InSight probe will study the formation of Mars, the fourth planet from the sun. Credit: NASA/JPL/Malin Space Science Systems

InSight carries three instruments vital to its mission. The Seismic Experiment Interior Structure (SEIS) sensor will study seismic waves from marsquakes (the Martian equivalent of earthquakes) to determine the structure of the interior of Mars. The Heat Flow and Physical Properties Package (HP³) will drill down almost 15 feet (5 meters) below the Martian surface—the deepest extraterrestrial excavation to date. As it drills, HP³ will record temperature changes to see how much heat remains from Mars’s formation billions of years ago. Scientists can determine the age of rocks, fossils, and other objects by measuring the radioactive elements in them, a science called radiogeology. A third InSight instrument will measure Mars’s magnetic field.

In an unusual arrangement, a robotic arm will move SEIS and HP³ from docks on the body of the lander to the surface of Mars. Tethers will control and power the instruments. Other than that, InSight’s design is pretty standard. Engineers reused much of the design of NASA’s Pheonix lander, which, in 2008, studied the history of water on Mars. By reusing this successful design, engineers saved many millions of dollars on the mission.

Two CubeSats (miniature satellites) hitched a ride on InSight’s rocket and are also traveling to Mars. The CubeSats are the first such satellites to venture beyond Earth’s orbit, and they will help transfer data from InSight during the probe’s landing.

InSight is scheduled to land on Mars on Nov. 26, 2018. Despite NASA’s strong recent record for Mars missions and the use of the proven Phoenix platform, success is far from guaranteed. Over the years, nearly two-thirds of all Mars missions have failed before completing their planned observations.