Parker Solar Probe to break speed records near the sun

The first vehicles that allowed humans to achieve much greater speed than on foot were horse-drawn carriages and boats powered by human muscle or wind. With the advent of the industrial revolution, engine-powered vehicles began to emerge. Eventually, airplanes were developed, and a few decades later, rockets were built, allowing us to reach extremely high speeds.

To send a probe into orbit, the vehicle must accelerate to about 4.9 miles per second. To fly to the Moon, the speed must reach about 6.7 miles per second. Without gravitational assistance, we can reach Mars by accelerating to about 7 miles per second. The fastest vehicle launched from Earth was the New Horizons probe, which visited Pluto. After its launch in 2006, it achieved a speed of almost 11 miles per second, though it still relied on the gravity of Jupiter during its journey.

On Earth, we achieve significantly lower speeds. One kilometer per second is equivalent to about 2,237 miles per hour, more than the maximum speed of most fighter jets. Passenger planes typically travel at speeds of around 621 miles per hour. On highways, the speed limit is 87 miles per hour, and the cruising speed of high-speed trains is about 217 miles per hour. In contrast, walking speed is only about 3.7 miles per hour.

Rockets remain the fastest mode of travel, as overcoming Earth's gravity requires high speeds. However, our technological capabilities, particularly achieving rapid high thrust through combustion, and economic factors impose limitations similar to those at the dawn of space flight. In many cases, we rely on a powerful ally—nature, specifically gravity.

On December 24, 2024 something unprecedented will occur. The Parker Solar Probe will reach a speed of 120 miles per second, which is just over 429,000 miles per hour. At that time, it will pass record-breakingly close to the Sun at a distance of 3.8 million miles from the photosphere, the layer we see during the day. Although there are no humans aboard the probe, if such a speed could be attained in Earth's atmosphere (overlooking issues like friction, acceleration, deceleration, and deadly stresses on a passenger), we could cover the distance between Warsaw and New York in 35 seconds. At this speed, we could also circle the planet more than 17 times in an hour.

Life on Earth depends on our daytime star, the Sun. Understanding its behavior, which provides phenomena like the northern lights, is crucial in the era of digital technology, satellites in Earth orbit, and planned manned interplanetary journeys. One of the most enigmatic elements of the Sun is the corona, its outermost layer.

People can see it with the naked eye during total solar eclipses as a jagged halo. The Parker Solar Probe was launched in 2018, and three years later, it became the first human-made vehicle to enter the Sun's corona and study it directly. This achievement occurred exactly 60 years after the concept of such a mission was conceived. The probe was named in honor of Eugene Parker, the scientist who predicted the existence of the solar wind. Parker passed away in 2022.

So far, the Parker Solar Probe has orbited the Sun 21 times. It has studied the so-called Alfvén surface, the area where the solar wind is generated, revealing its irregular shape. The probe also discovered a zone around the Sun where interplanetary dust heats to the point of sublimation, turning into gas.

The probe has also studied the behavior of the magnetic field inside the corona, uncovering the mechanism of magnetic reconnection that drives the solar wind. Its orbit through various regions of the solar corona has demonstrated the complexity of the paths high-energy particles take before embarking on a journey away from the star. Until now, these were all just theories and hypotheses. Data from the probe has also suggested the likely source of the Geminid meteor shower, which peaked in mid-December.

During its first orbit around the Sun, the Parker Solar Probe achieved a speed of 59 miles per second, breaking the previous record of 44 miles per second set by the Helios-B probe in the 1970s. However, our home star cannot be moved to serve as a gravitational slingshot in any mission. The record speed is possible because of an orbit that wraps closely around the Sun's surface. Consequently, the probe's orbit has been steadily tightened since its launch. The gravitational assist maneuver from Venus, which placed the Parker Solar Probe in the closest-ever orbit around the Sun, took place on November 6, 2024.

It's important to note that the probe's speed is not constant. It accelerates at the closest point in its orbit to the Sun (called perihelion) but significantly slows down as it moves away from the star. When the probe reaches the farthest point of its current orbit before turning back toward the Sun to gather speed again, it will travel at about 7 miles per second. Even though the Parker Solar Probe will accelerate to 120 miles per second, this does not mean it will fly off into the far reaches of space like the Voyagers launched from Earth. For that to happen, the probe would need to travel at about 384 miles per second relative to the Sun. Today, even a return to the vicinity of Earth is impossible, but it is unnecessary.

What will happen on December 24 will remain a mystery until Friday, December 27, when communication with the probe will be reestablished, and scientists will download the first data. Then, after about 88 days, in March 2025, the probe will return near the Sun and continue its mission several more times.

It's important to note that all speeds are given relative to a specific reference point. The direction of movement is also significant. The speeds achieved by probes launched from Earth are usually given relative to our planet.

The speed of the Parker Solar Probe is measured relative to the Sun. If we wanted to determine the resultant speed relative to even larger structures, the result would be surprising. The Solar System orbits the center of the Milky Way at a speed of 143 miles per second, and our galaxy moves even faster relative to the center of the Virgo Supercluster.