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Dawn spacecraft

Dawn spacecraft revealed groundbreaking findings on early solar system

The Dawn spacecraft was a groundbreaking mission launched by NASA in 2007 to explore the early days of our solar system by studying two of the largest objects in the asteroid belt – Vesta and Ceres. This $500 million spacecraft equips ion propulsion technology. This allows it to achieve impressive acceleration and make a significant contribution to the field of space exploration. During its eleven-year mission, Dawn provided critical data on the formation and evolution of celestial bodies, including key findings about Vesta and Ceres, the location of their formation, the potential for oceans on dwarf planets, and the discovery of organic molecules on Ceres.

Asteroid Vesta
NASA’s Dawn spacecraft took this image of asteroid Vesta on July 24, 2011, from a distance of about 3,200 miles (5,100 kilometers). Dawn entered orbit around Vesta on July 15, 2011. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

First, we should know;

What is the Dawn spacecraft?

Dawn spacecraft was a mission launched by NASA in September 2007 to study two of the largest objects in the asteroid belt – Vesta and Ceres. The spacecraft used ion propulsion, a space propulsion breakthrough. The total cost of the spacecraft is $500 million, which includes $370 million for building and launching the spacecraft and $130 million for 11 years of operations and data analysis. At launch, the spacecraft weighed 1,647.1 pounds and carried 937 pounds of xenon propellant for the ion propulsion system. The spacecraft’s pointing control at launch was achieved with four reaction wheels, augmented by 100.5 pounds of hydrazine.

Vesta Snowman Crater
Dawn took this picture of a group of craters resembling a snowman on asteroid Vesta on Aug. 20, 2011. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

What is the functional structure of the Dawn spacecraft?

The ion propulsion system of the spacecraft consisted of three thrusters. Each of which measured 13 inches in length and 16 inches in diameter, weighing 20 pounds each. The system produced a thrust ranging from 0.07 to 0.33-ounce propulsion system allowing the spacecraft to achieve an acceleration of 0 – 60 mph in 4 days at full thrust.

“It is a tribute to all those involved in the design and operations of this remarkable spacecraft,” said Marc Rayman. He is the chief engineer for the Dawn mission and former project manager for Deep Space 1, in a statement. “I am delighted that it will be Dawn that surpasses DS1’s record.”

The launch of the Dawn spacecraft was on September 27, 2007, at 7:34 a.m. United Launch Alliance, Denver provided EDT from Cape Canaveral Air Force Station, Florida, Pad 17B, aboard a Delta II Heavy 2925H-9.5 rocket, including a Star 48 upper stage. The mission had two extended missions, the first from July 2016 to October 2017, and the second from October 2017 to November 2018. The spacecraft’s mission came to an end on November 1, 2018, after completing its objectives. The Dawn spacecraft was a remarkable technological achievement and a significant milestone in the exploration of the solar system.

Now let’s find out;

What did the Dawn spacecraft discover?

NASA’s Dawn mission began in 2007 to study early solar system processes. The spacecraft visited two-time capsules of the solar system, Vesta and Ceres, which are the largest bodies of the main asteroid belt. Dawn’s mission aimed to build a detailed picture of the early days of the solar system. It was formed 4.6 billion years ago. Dawn mapped these planet-like worlds from orbit. As it provides key pieces of data that scientists could not obtain using telescopes or brief flybys.

Ceres Occator Crater
This image of Ceres was made in September 2017 from views that Dawn took at about 240 miles (385 kilometers) above the surface. At the center is Occator Crater, home to the brightest area on Ceres. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA


Location is Key:

NASA’s Dawn mission discovered that the location of the formation of celestial bodies in the early solar system is essential to understanding their evolution. Scientists studied Vesta and Ceres to determine their histories, and the findings from the mission indicate that Vesta likely formed in the inner solar system and remained there. Whereas Ceres likely formed farther from the Sun and drifted inward. They differ in local action and determined the amount of water present in the bodies, which played a crucial role in how they cooled. Vesta cooled slowly and formed a metallic core and rocky mantle and crust. While Ceres cooled rapidly and formed a stratified interior consisting of a water-rich rock mantle and a water-rich ice and hydrate outer shell. These findings have implications for early solar system and planetary migration models.

Dawn’s Findings on Vesta:

The Dawn mission revealed important findings about the dwarf planet Vesta, including the confirmation that the giant basin in Vesta’s southern hemisphere, Rheasilvia, is more than 310 miles in diameter and 12 miles deep. The mission also discovered a second impact basin what we call Veneneia.  Rheasilvia partially covered it.

Christopher Russell, the principal investigator for Dawn. He stated that: “We went to Vesta to fill in the blanks of our knowledge about the early history of our solar system”.

The data from the Dawn spacecraft shows that these giant impacts created dozens of canyons. Hence, rivals the size of the Grand Canyon, and the surface of the southern hemisphere appears younger than the northern hemisphere due to the massive impact that carved Rhea Silvia. Furthermore, Dawn found water-rich minerals on Vesta’s surface. Since asteroids or comets from the outer solar system delivered them to planets.

view of the floor of Occator Crater on Ceres
This view of the floor of Occator Crater on Ceres is based on images taken by Dawn in 2018. Occator Crater is 57 miles (92 kilometers) across. The salty liquid released during the freezing of the water-rich floor formed bright pits and mounds. It followed the crater-forming impact about 20 million years ago. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/USRA/LPI

Dwarf Planets and Oceans:

Dawn’s findings indicate that not only icy moons, but also dwarf planets could have sustained oceans for a significant portion of their existence, and may still possess them. Ceres are an essential element in understanding ocean worlds. As its crust consists of a combination of ice, minerals, salts, and other substances, making it a relic of an “ocean world”.  It retains the chemical composition of its previous ocean and evidence of surface interactions. The observations made by Dawn suggest that some amount of salty liquid could still exist beneath its surface. Ceres, as an advanced dwarf planet, has the potential to offer insights into the environmental conditions of other ocean worlds.

Organic Molecules at Ceres:

Scientists remain curious about the organics discovered by Dawn at Ceres. According to the Dawn team, these organics were likely generated in the dwarf planet’s deep ocean, beginning from its innards. The organics were mostly aliphatic carbon-hydrogen chains. Ceres’ loose surface material contains considerable quantities of carbon globally, despite the organics being found in a small zone. Despite this, the origin of the organics found on Ceres remains unknown.

Lastly, we should conclude this by,

Where is the dawn spacecraft now?

The Dawn spacecraft was a pioneering mission that greatly expanded our understanding of the early solar system and the evolution of celestial bodies. The mission ended on Nov. 1, 2018. The mission was a great success. It was no longer able to communicate with Earth due to the reason the spacecraft ran out of fuel. Furthermore, experts say the spacecraft is still orbiting around Ceres.

When the mission came to an end, Thomas Zurbuchen, the associate administrator for NASA’s Science Mission Directorate in Washington, D.C says: “Today, we celebrate the end of our Dawn mission — its incredible technical achievements, the vital science it gave us. And the entire team who enabled the spacecraft to make these discoveries”. Moreover, he says: “The astounding images and data that Dawn collected from Vesta and Ceres are critical to understanding the history and evolution of our solar system.”

Dawn's mission statistics
Dawn’s end of mission statistics. Credit: NASA/JPL-Caltech

The spacecraft’s ion propulsion technology and advanced instruments allowed it to gather a wealth of scientific data during its 11 years of operation including more than 51,000 hours of ion engine thrusting, 172 GB of science data, 3,052 orbits around Vesta and Ceres, and over 100,000 images. Additionally, the spacecraft traveled over 4.3 billion miles since its launch in 2007. It reached a record distance of 367+ million miles from Earth. The success of the Dawn mission stands as a testament to the ingenuity and perseverance of NASA’s scientists and engineers. It continues to push the boundaries of our knowledge of the universe.

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