Countdown to the Fastest Human-Made Object: Parker Solar Probe’s Date with the Sun

A groundbreaking moment in space exploration will arrive in just under a year. On December 24, 2024, NASA’s revolutionary Parker Solar Probe will achieve the closest-ever human-made approach to the Sun. Travelling at a blistering 195 km/s, the probe will race past our star a mere 6.1 million km away, moving faster than any previous spacecraft at 435,000 mph.

This will shatter multiple records as the probe flies through the Sun’s blazing outer atmosphere for longer than ever to unlock clues about the solar corona’s heating and the solar wind’s acceleration.

The Parker Solar Probe has ventured closer towards actually “touching” the Sun than anyone previously imagined possible. Already, it has withstood a fierce bombardment of solar radiation, which will only intensify further in the lead-up to December 2024.

Its cutting-edge carbon heat shield and clever orbital trajectory corrections have prepared it to fulfil an extraordinarily ambitious quest. By its mission’s end, it will have spent seven years completing 24 daring orbits, coming within 6.2 million km of our star’s surface after enduring temperatures up to 1377°C. The data it gathers could revolutionize prediction abilities for solar storms, providing a lifeline for safeguarding astronauts and infrastructure in space and on Earth.

Preparing to “Touch the Sun”

To pull off its death-defying solar passes, the Parker probe relies on bleeding-edge engineering solutions for protection and precise positioning. Measuring just 3.3 ft x 9.8 ft x 7.5 ft, there is little margin for error.

Above: As NASA’s intrepid Parker Solar Probe completed its ninth close solar pass in 2022, its cameras glimpsed mysterious coronal streamers from a revelatory vantage point within the Sun’s outer atmosphere. These giant structures appear as bright twisting plasma tendrils anchored at one end in the solar surface and cascading outward. During previous flybys farther from the Sun, the probe had only captured oblique perspectives of their dazzling glow.

Parker’s payload of four instrument suites peers out from behind a 4.5-inch thick, carbon-composite heat shield spanning 8 feet in diameter. This shield’s carbon foam core and multiple reflective and refractive layers allow it to withstand searing coronial temperatures over 2,500°F while maintaining internal instruments at a cool 85°F. Weighing just 160 pounds, this lightweight yet hardy shield points permanently at the Sun to cast life-saving shade.

The probe’s early trajectory relied on 7 gravity assists from flybys of Venus, each ratcheting its path closer to the Sun. Timing these manoeuvres to utilize Venus’s orbital position has taken considerable accuracy. Most recently, in November 2021, Parker swung past Venus for the 5th time, correcting its trajectory to bring perihelion just 11.1 solar radii away from the Sun’s centre.

While the last of its scheduled Venus will occur on November 6 2024, effectively cementing its final solar trajectory, most course calibrations are complete. Thanks to the Sun’s immense gravitation, Parker’s orbit will continue decaying inwards. The spacecraft completes a full revolution every 3 months, building up speed, which will peak at 430,000 mph in late 2024.

A Moment in the Sun: Goals for Historical December 2024 Flyby

As PARKER crosses its ultimate perihelion on Christmas Eve 2024, it will claim the title of fastest-ever human creation at 176.5 km/s. Hurtling past the Sun at this breakneck pace, it will log invaluable scientific measurements that no earlier mission could replicate. For over a week around its closest approach, Parker’s instruments can soak up data on the immediate environment of solar material and energy flows.

Previous brief forays into the outermost atmospheric region of the Sun, its corona, left many questions about the extreme heating observed there needing to be solved. Temperatures leap from thousands to millions of degrees higher than at the solar surface. What physical processes prompt this counterintuitive thermal inversion? Parker’s longest-ever direct looks into the corona aim to capture clues like electromagnetic waves and nanoflares that betray the energy sources tantalizing scientists.

In addition to solar heating riddles, Parker offers an unmissable opportunity to shed light on the mystery of solar wind acceleration. As the supersonic torrent of charged particles perpetually blows outward from the Sun, what gives them their initial kick to such outrageous speeds? Whether through magnetohydrodynamic shocks, reconnection events, or other phenomena, December 2024 presents the best chance of elucidating the solar wind’s origins.

These astrophysical questions and their answers bear immense practical value. NASA’s quest to sustain human presence in space, especially reviving crewed lunar exploration, demands accurate forecasting of hazardous space weather spawned by solar outbursts. Parker lays the essential groundwork to model and predict this tumultuous space climate by decoding the physics underlying solar outflow variability. Both billionaire-led commercial space travel ambitions and governmental orbiting infrastructure benefit enormously from enhanced awareness of coming solar storms.

Beyond 2024: Probe’s Ongoing Contributions

While the December 2024 milestone will crown its gravity-assist manoeuvring efforts, the industrious Parker Solar Probe’s work will continue long after. Until projected retirement in 2025, it will utilize solar panels and chemical propulsion to regulate positioning, capturing data during indirect incoming and outgoing phases around perihelion events. Routine telemetry, even at great distances, also allows it to uplink stored measurements from closer encounters.

Its resilience against the harsh space environment in the Vulcanoids region will push engineering limits. Parker’s two completed science phases in 2018 and 2019 have scored fascinating first-time observations. These include witnessing “switchbacks” – spontaneous flips in solar magnetic field polarity and plasma flows hinting at acceleration forces. Parker also stunned scientists with beautiful images from its WISPR instrument revealing Venus’s gleaming nightside geography.

Most recently, in 2021, telltale plasma characteristics signalled the spacecraft’s passage through the Sun’s critical Alfvén boundary for the first time. Crossing this elusive zone demonstrated Parker’s definitive beginning to “touch” the Sun through its magnetic connection to the solar surface.

Pushing Boundaries of Solar Science

The probe demonstrates incredible engineering prowess as exceptionally as the astrophysicist whose namesake it bears. Dr. Eugene Parker’s groundbreaking solar wind theory in 1958 set this spacecraft in motion to confront the star he had studied his whole career. In proving the concepts Parker wrote down 65 years ago, this ambitious mission partakes in a circularity that the late scientist would have found poetic.

On route to its December 2024 solar rendezvous, Parker has already substantially expanded heliospheric knowledge frontiers. But its best and most ravelling findings from measuring plasmas and radio signatures in the Sun’s outer sanctum lie ahead. As data pours in from ever-closer passes, revelations about coronal heating, particle acceleration, and space weather processes grow imminent. The spacecraft still has history left to make when its last Venus gravity slingshot.

December 2023