From The Harvard Gazette (US) : “Spacecraft enters sun’s corona for the first time in history”

From The Harvard Gazette (US)

At

Harvard University (US)

December 14, 2021
Nadia Whitehead

1
Artist’s conception of The Parker Solar Probe | NASA (US) spacecraft approaching the sun. Credit: Steve Gribben The National Aeronautics and Space Agency(US)/The Johns Hopkins University Applied Physics Laboratory (US)/

Harvard-led team engineered key instrument to verify craft crossed over into the 2 million degrees F environment

A spacecraft launched by NASA has done what was once thought impossible. On April 28, the Parker Solar Probe successfully entered the corona of the sun — an extreme environment that’s roughly 2 million degrees Fahrenheit.

The historic moment was achieved thanks to a large collaboration of scientists and engineers, including members of The Harvard Smithsonian Center for Astrophysics (US) who built and monitor a key instrument onboard the probe: the Solar Probe Cup. The cup collects particles from the sun’s atmosphere that helped scientists verify that the spacecraft had indeed crossed into the corona.

“The goal of this entire mission is to learn how the sun works. We can accomplish this by flying into the solar atmosphere,” says Michael Stevens, an astrophysicist at the CfA who helps monitor the cup. “The only way to do that is for the spacecraft to cross the outer boundary, which scientists call the Alfvén point. So, a basic part of this mission is to be able to measure whether or not we crossed this critical point.”

The corona is the outermost layer of the sun’s atmosphere where strong magnetic fields bind plasma and prevent turbulent solar winds from escape. The Alfvén point is when solar winds exceed a critical speed and can break free of the corona and the sun’s magnetic fields. Prior to April 28, the spacecraft had been flying just beyond this point.

“If you look at close-up pictures of the sun, sometimes you’ll see these bright loops or hairs that seem to break free from the sun but then reconnect with it,” Stevens explains. “That’s the region we’ve flown into — an area where the plasma, atmosphere and wind are magnetically stuck and interacting with the sun.”

“The goal of this entire mission is to learn how the sun works. We can accomplish this by flying into the solar atmosphere,” says Michael Stevens, an astrophysicist at the CfA who helps monitor the cup. “The only way to do that is for the spacecraft to cross the outer boundary, which scientists call the Alfvén point. So, a basic part of this mission is to be able to measure whether or not we crossed this critical point.”

The corona is the outermost layer of the sun’s atmosphere where strong magnetic fields bind plasma and prevent turbulent solar winds from escape. The Alfvén point is when solar winds exceed a critical speed and can break free of the corona and the sun’s magnetic fields. Prior to April 28, the spacecraft had been flying just beyond this point.

“If you look at close-up pictures of the sun, sometimes you’ll see these bright loops or hairs that seem to break free from the sun but then reconnect with it,” Stevens explains. “That’s the region we’ve flown into — an area where the plasma, atmosphere and wind are magnetically stuck and interacting with the sun.”

According to data collected by the cup, the spacecraft entered the corona three times on April 28, at one point for up to five hours. A scientific paper describing the milestone has been accepted for publication in the Physical Review Letters.

CfA astrophysicist Anthony Case, the instrument scientist for the Solar Probe Cup, says the instrument itself is an incredible feat of engineering.

“The amount of light hitting the Parker Solar Probe determines how hot the spacecraft will get,” Case explains. “While much of the probe is protected by a heat shield, our cup is one of only two instruments that stick out and have no protection. It’s directly exposed to the sunlight and operating at a very high temperature while it’s making these measurements; it’s literally red-hot, with parts of the instrument at more than 1,800 degrees Fahrenheit [1,000 degrees Celsius], and glowing red-orange.”

To avoid degradation, the device is constructed of materials that have high melting points, like tungsten, niobium, molybdenum and sapphire.

But the success of the Parker Solar Probe represents much more than technological innovation. There are many mysteries about Earth’s closest star that scientists are hoping the probe can help solve.

For example, “We don’t actually know why the outer atmosphere of the Sun is so much hotter than the sun itself,” Stevens says. “The sun is 10,000 degrees Fahrenheit [5,500 degrees Celsius], but its atmosphere is about 3.6 million degrees Fahrenheit [2 million degrees Celsius].”

He adds, “We know that the energy comes from the churning magnetic fields bubbling up through the surface of the sun, but we do not know how the sun’s atmosphere absorbs this energy.”

In addition, outbursts from the Sun, like solar flares and high-speed solar winds, can have a direct impact on Earth, disrupting power grids and radio communication.

The Parker Solar Probe can help better understand all these phenomena as it continues to orbit the sun and take measurements and data for scientists to analyze here on Earth.

Case says, “The plasma around the Sun can act as a laboratory that teaches us about processes taking place in almost every astronomical object across the entire universe.”

The historic achievement of the Parker Solar Probe was announced at a press conference on Tuesday at the fall meeting of the American Geophysical Union (AGU). The press conference panel included former CfA scientist Justin Kasper and Kelly Korreck who is currently on rotation at NASA headquarters. Both worked on the probe during their tenure at the CfA.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Harvard University campus

Harvard University (US) is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s bestknown landmark.

Harvard University (US) has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

The Massachusetts colonial legislature, the General Court, authorized Harvard University (US)’s founding. In its early years, Harvard College primarily trained Congregational and Unitarian clergy, although it has never been formally affiliated with any denomination. Its curriculum and student body were gradually secularized during the 18th century, and by the 19th century, Harvard University (US) had emerged as the central cultural establishment among the Boston elite. Following the American Civil War, President Charles William Eliot’s long tenure (1869–1909) transformed the college and affiliated professional schools into a modern research university; Harvard became a founding member of the Association of American Universities in 1900. James B. Conant led the university through the Great Depression and World War II; he liberalized admissions after the war.

The university is composed of ten academic faculties plus the Radcliffe Institute for Advanced Study. Arts and Sciences offers study in a wide range of academic disciplines for undergraduates and for graduates, while the other faculties offer only graduate degrees, mostly professional. Harvard has three main campuses: the 209-acre (85 ha) Cambridge campus centered on Harvard Yard; an adjoining campus immediately across the Charles River in the Allston neighborhood of Boston; and the medical campus in Boston’s Longwood Medical Area. Harvard University (US)’s endowment is valued at $41.9 billion, making it the largest of any academic institution. Endowment income helps enable the undergraduate college to admit students regardless of financial need and provide generous financial aid with no loans The Harvard Library is the world’s largest academic library system, comprising 79 individual libraries holding about 20.4 million items.

Harvard University (US) has more alumni, faculty, and researchers who have won Nobel Prizes (161) and Fields Medals (18) than any other university in the world and more alumni who have been members of the U.S. Congress, MacArthur Fellows, Rhodes Scholars (375), and Marshall Scholars (255) than any other university in the United States. Its alumni also include eight U.S. presidents and 188 living billionaires, the most of any university. Fourteen Turing Award laureates have been Harvard affiliates. Students and alumni have also won 10 Academy Awards, 48 Pulitzer Prizes, and 108 Olympic medals (46 gold), and they have founded many notable companies.

Colonial

Harvard University (US) was established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. In 1638, it acquired British North America’s first known printing press. In 1639, it was named Harvard College after deceased clergyman John Harvard, an alumnus of the University of Cambridge(UK) who had left the school £779 and his library of some 400 volumes. The charter creating the Harvard Corporation was granted in 1650.

A 1643 publication gave the school’s purpose as “to advance learning and perpetuate it to posterity, dreading to leave an illiterate ministry to the churches when our present ministers shall lie in the dust.” It trained many Puritan ministers in its early years and offered a classic curriculum based on the English university model—many leaders in the colony had attended the University of Cambridge—but conformed to the tenets of Puritanism. Harvard University (US) has never affiliated with any particular denomination, though many of its earliest graduates went on to become clergymen in Congregational and Unitarian churches.

Increase Mather served as president from 1681 to 1701. In 1708, John Leverett became the first president who was not also a clergyman, marking a turning of the college away from Puritanism and toward intellectual independence.

19th century

In the 19th century, Enlightenment ideas of reason and free will were widespread among Congregational ministers, putting those ministers and their congregations in tension with more traditionalist, Calvinist parties. When Hollis Professor of Divinity David Tappan died in 1803 and President Joseph Willard died a year later, a struggle broke out over their replacements. Henry Ware was elected to the Hollis chair in 1805, and the liberal Samuel Webber was appointed to the presidency two years later, signaling the shift from the dominance of traditional ideas at Harvard to the dominance of liberal, Arminian ideas.

Charles William Eliot, president 1869–1909, eliminated the favored position of Christianity from the curriculum while opening it to student self-direction. Though Eliot was the crucial figure in the secularization of American higher education, he was motivated not by a desire to secularize education but by Transcendentalist Unitarian convictions influenced by William Ellery Channing and Ralph Waldo Emerson.

20th century

In the 20th century, Harvard University (US)’s reputation grew as a burgeoning endowment and prominent professors expanded the university’s scope. Rapid enrollment growth continued as new graduate schools were begun and the undergraduate college expanded. Radcliffe College, established in 1879 as the female counterpart of Harvard College, became one of the most prominent schools for women in the United States. Harvard University (US) became a founding member of the Association of American Universities in 1900.

The student body in the early decades of the century was predominantly “old-stock, high-status Protestants, especially Episcopalians, Congregationalists, and Presbyterians.” A 1923 proposal by President A. Lawrence Lowell that Jews be limited to 15% of undergraduates was rejected, but Lowell did ban blacks from freshman dormitories.

President James B. Conant reinvigorated creative scholarship to guarantee Harvard University (US)’s preeminence among research institutions. He saw higher education as a vehicle of opportunity for the talented rather than an entitlement for the wealthy, so Conant devised programs to identify, recruit, and support talented youth. In 1943, he asked the faculty to make a definitive statement about what general education ought to be, at the secondary as well as at the college level. The resulting Report, published in 1945, was one of the most influential manifestos in 20th century American education.

Between 1945 and 1960, admissions were opened up to bring in a more diverse group of students. No longer drawing mostly from select New England prep schools, the undergraduate college became accessible to striving middle class students from public schools; many more Jews and Catholics were admitted, but few blacks, Hispanics, or Asians. Throughout the rest of the 20th century, Harvard became more diverse.

Harvard University (US)’s graduate schools began admitting women in small numbers in the late 19th century. During World War II, students at Radcliffe College (which since 1879 had been paying Harvard University (US) professors to repeat their lectures for women) began attending Harvard University (US) classes alongside men. Women were first admitted to the medical school in 1945. Since 1971, Harvard University (US) has controlled essentially all aspects of undergraduate admission, instruction, and housing for Radcliffe women. In 1999, Radcliffe was formally merged into Harvard University (US).

21st century

Drew Gilpin Faust, previously the dean of the Radcliffe Institute for Advanced Study, became Harvard University (US)’s first woman president on July 1, 2007. She was succeeded by Lawrence Bacow on July 1, 2018.