From Brown University: “Differences between the Moon’s near and far sides linked to colossal ancient impact”
April 8, 2022
Kevin Stacey
kevin_stacey@brown.edu
401-863-3766
A new study reveals that an ancient collision on the Moon’s south pole changed patterns of convection in the lunar mantle, concentrating a suite of heat-producing elements on the nearside. Those elements played a role in creating the vast lunar mare visible from Earth. CREDIT: Matt Jones. https://www.eurasiareview.com
New research shows how the impact that created the Moon’s South Pole–Aitken basin is linked to the stark contrast in composition and appearance between the two sides of the Moon.
The face that the Moon shows to Earth looks far different from the one it hides on its far side. The nearside is dominated by the lunar mare — the vast, dark-colored remnants of ancient lava flows. The crater-pocked far side, on the other hand, is virtually devoid of large-scale mare features. Why the two sides are so different is one of the Moon’s most enduring mysteries.
Now, researchers have a new explanation for the two-faced Moon — one that relates to a giant impact billions of years ago near the Moon’s south pole.
A new study published in the journal Science Advances shows that the impact that formed the Moon’s giant South Pole–Aitken (SPA) basin would have created a massive plume of heat that propagated through the lunar interior. That plume would have carried certain materials — a suite of rare-Earth and heat-producing elements — to the Moon’s nearside. That concentration of elements would have contributed to the volcanism that created the nearside volcanic plains.
“We know that big impacts like the one that formed SPA would create a lot of heat,” said Matt Jones, a Ph.D. candidate at Brown University and the study’s lead author. “The question is how that heat affects the Moon’s interior dynamics. What we show is that under any plausible conditions at the time that SPA formed, it ends up concentrating these heat-producing elements on the nearside. We expect that this contributed to the mantle melting that produced the lava flows we see on the surface.”
The study was a collaboration between Jones and his advisor Alexander Evans, an assistant professor at Brown, along with researchers from Purdue University, The University of Arizona Lunar and Planetary Laboratory & Department of Planetary Sciences, Stanford University and NASA JPL/Caltech.
The Moon’s nearside (left) is dominated by vast volcanic deposits, while the far side (right) has far fewer). Why the two sides are so different is an enduring lunar mystery.
The differences between the near and far sides of the Moon were first revealed in the 1960s by the Soviet Luna missions and the U.S. Apollo program. While the differences in volcanic deposits are plain to see, future missions would reveal differences in the geochemical composition as well. The nearside is home to a compositional anomaly known as the Procellarum KREEP terrane (PKT) — a concentration of potassium (K), rare earth elements (REE), phosphorus (P), along with heat-producing elements like thorium. KREEP seems to be concentrated in and around Oceanus Procellarum, the largest of the nearside volcanic plains, but is sparse elsewhere on the Moon.
Some scientists have suspected a connection between the PKT and the nearside lava flows, but the question of why that suite of elements was concentrated on the nearside remained. This new study provides an explanation that is connected to the South Pole–Aitken basin, the second largest known impact crater in the solar system.
For the study, the researchers conducted computer simulations of how heat generated by a giant impact would alter patterns of convection in the Moon’s interior, and how that might redistribute KREEP material in the lunar mantle. KREEP is thought to represent the last part of the mantle to solidify after the Moon’s formation. As such, it likely formed the outermost layer of mantle, just beneath the lunar crust. Models of the lunar interior suggest that it should have been more or less evenly distributed beneath the surface. But this new model shows that the uniform distribution would be disrupted by the heat plume from the SPA impact.
According to the model, the KREEP material would have ridden the wave of heat emanating from the SPA impact zone like a surfer. As the heat plume spread beneath the Moon’s crust, that material was eventually delivered en masse to the nearside. The team ran simulations for a number of different impact scenarios, from dead-on hit to a glancing blow. While each produced differing heat patterns and mobilized KREEP to varying degrees, all created KREEP concentrations on the nearside, consistent with the PKT anomaly.
The researchers say the work provides a credible explanation for one of the Moon’s most enduring mysteries.
“How the PKT formed is arguably the most significant open question in lunar science,” Jones said. “And the South Pole–Aitken impact is one of the most significant events in lunar history. This work brings those two things together, and I think our results are really exciting.”
See the full article here .
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Brown University is a private Ivy League research university in Providence, Rhode Island. Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.
At its foundation, Brown University was the first college in North America to accept students regardless of their religious affiliation. The university is home to the oldest applied mathematics program in the United States, the oldest engineering program in the Ivy League, and the third-oldest medical program in New England. The university was one of the early doctoral-granting U.S. institutions in the late 19th century, adding masters and doctoral studies in 1887. In 1969, Brown adopted its “Open Curriculum” after a period of student lobbying. The new curriculum eliminated mandatory “general education” distribution requirements, made students “the architects of their own syllabus” and allowed them to take any course for a grade of satisfactory (Pass) or no-credit (Fail) which is unrecorded on external transcripts. In 1971, Brown’s coordinate women’s institution, Pembroke College, was fully merged into the university.
Admission is among the most selective in the United States; in 2021, the university reported an acceptance rate of 5.4%.
The university comprises the College; the Graduate School; Alpert Medical School; the School of Engineering; the School of Public Health and the School of Professional Studies. Brown’s international programs are organized through The Watson Institute for International and Public Affairs at Brown University , and the university is academically affiliated with the UChicago Marine Biological Laboratory in Woods Hole, Massachusetts (US) and The Rhode Island School of Design. In conjunction with the Rhode Island School of Design, Brown offers undergraduate and graduate dual degree programs.
Brown’s main campus is located in the College Hill neighborhood of Providence, Rhode Island. The university is surrounded by a federally listed architectural district with a dense concentration of Colonial-era buildings. Benefit Street, which runs along the western edge of the campus, contains one of the richest concentrations of 17th and 18th century architecture in the United States.
As of November 2019, nine Nobel Prize winners have been affiliated with Brown as alumni, faculty, or researchers, as well as seven National Humanities Medalists and ten National Medal of Science laureates. Other notable alumni include 26 Pulitzer Prize winners, 18 billionaires, one U.S. Supreme Court Chief Justice, four U.S. Secretaries of State, 99 members of the United States Congress, 57 Rhodes Scholars, 21 MacArthur Genius Fellows, and 37 Olympic medalists.
The foundation and the charter
In 1761, three residents of Newport, Rhode Island, drafted a petition to the colony’s General Assembly:
“That your Petitioners propose to open a literary institution or School for instructing young Gentlemen in the Languages, Mathematics, Geography & History, & such other branches of Knowledge as shall be desired. That for this End… it will be necessary… to erect a public Building or Buildings for the boarding of the youth & the Residence of the Professors.”
The three petitioners were Ezra Stiles, pastor of Newport’s Second Congregational Church and future president of Yale University; William Ellery, Jr., future signer of the United States Declaration of Independence; and Josias Lyndon, future governor of the colony. Stiles and Ellery later served as co-authors of the college’s charter two years later. The editor of Stiles’s papers observes, “This draft of a petition connects itself with other evidence of Dr. Stiles’s project for a Collegiate Institution in Rhode Island, before the charter of what became Brown University.”
The Philadelphia Association of Baptist Churches were also interested in establishing a college in Rhode Island—home of the mother church of their denomination. At the time, the Baptists were unrepresented among the colonial colleges; the Congregationalists had Harvard University and Yale University, the Presbyterians had the College of New Jersey (later Princeton University), and the Episcopalians had The William & Mary College and King’s College (later Columbia University). Isaac Backus, a historian of the New England Baptists and an inaugural trustee of Brown, wrote of the October 1762 resolution taken at Philadelphia:
“The Philadelphia Association obtained such an acquaintance with our affairs, as to bring them to an apprehension that it was practicable and expedient to erect a college in the Colony of Rhode-Island, under the chief direction of the Baptists; … Mr. James Manning, who took his first degree in New-Jersey college in September, 1762, was esteemed a suitable leader in this important work.”
James Manning arrived at Newport in July 1763 and was introduced to Stiles, who agreed to write the charter for the college. Stiles’ first draft was read to the General Assembly in August 1763 and rejected by Baptist members who worried that their denomination would be underrepresented in the College Board of Fellows. A revised charter written by Stiles and Ellery was adopted by the Rhode Island General Assembly on March 3, 1764, in East Greenwich.
In September 1764, the inaugural meeting of the corporation—the college’s governing body—was held in Newport’s Old Colony House. Governor Stephen Hopkins was chosen chancellor, former and future governor Samuel Ward vice chancellor, John Tillinghast treasurer, and Thomas Eyres secretary. The charter stipulated that the board of trustees should be composed of 22 Baptists, five Quakers, five Episcopalians, and four Congregationalists. Of the 12 Fellows, eight should be Baptists—including the college president—”and the rest indifferently of any or all Denominations.”
At the time of its creation, Brown’s charter was a uniquely progressive document. Other colleges had curricular strictures against opposing doctrines, while Brown’s charter asserted, “Sectarian differences of opinions, shall not make any Part of the Public and Classical Instruction.” The document additionally “recognized more broadly and fundamentally than any other [university charter] the principle of denominational cooperation.” The oft-repeated statement that Brown’s charter alone prohibited a religious test for College membership is inaccurate; other college charters were similarly liberal in that particular.
The college was founded as Rhode Island College, at the site of the First Baptist Church in Warren, Rhode Island. James Manning was sworn in as the college’s first president in 1765 and remained in the role until 1791. In 1766, the college authorized Rev. Morgan Edwards to travel to Europe to “solicit Benefactions for this Institution.” During his year-and-a-half stay in the British Isles, the reverend secured funding from benefactors including Thomas Penn and Benjamin Franklin.
In 1770, the college moved from Warren to Providence. To establish a campus, John and Moses Brown purchased a four-acre lot on the crest of College Hill on behalf of the school. The majority of the property fell within the bounds of the original home lot of Chad Brown, an ancestor of the Browns and one of the original proprietors of Providence Plantations. After the college was relocated to the city, work began on constructing its first building.
A building committee, organized by the corporation, developed plans for the college’s first purpose-built edifice, finalizing a design on February 9, 1770. The subsequent structure, referred to as “The College Edifice” and later as University Hall, may have been modeled on Nassau Hall, built 14 years prior at the College of New Jersey. President Manning, an active member of the building process, was educated at Princeton and might have suggested that Brown’s first building resemble that of his alma mater.
The College
Founded in 1764, the college is Brown’s oldest school. About 7,200 undergraduate students are enrolled in the college, and 81 concentrations are offered. For the graduating class of 2020 the most popular concentrations were Computer Science; Economics; Biology; History; Applied Mathematics; International Relations and Political Science. A quarter of Brown undergraduates complete more than one concentration before graduating. If the existing programs do not align with their intended curricular interests, undergraduates may design and pursue independent concentrations.
35 percent of undergraduates pursue graduate or professional study immediately, 60 percent within 5 years, and 80 percent within 10 years. For the Class of 2009, 56 percent of all undergraduate alumni have since earned graduate degrees. Among undergraduate alumni who go on to receive graduate degrees, the most common degrees earned are J.D. (16%), M.D. (14%), M.A. (14%), M.Sc. (14%), and Ph.D. (11%). The most common institutions from which undergraduate alumni earn graduate degrees are Brown University, Columbia University, and Harvard University.
The highest fields of employment for undergraduate alumni ten years after graduation are education and higher education (15%), medicine (9%), business and finance (9%), law (8%), and computing and technology (7%).
Brown and RISD
Since its 1893 relocation to College Hill, Rhode Island School of Design (RISD) has bordered Brown to its west. Since 1900, Brown and RISD students have been able to cross-register at the two institutions, with Brown students permitted to take as many as four courses at RISD to count towards their Brown degree. The two institutions partner to provide various student-life services and the two student bodies compose a synergy in the College Hill cultural scene.
Rankings
Brown University is accredited by the New England Commission of Higher Education. For their 2021 rankings, The Wall Street Journal/Times Higher Education ranked Brown 5th in the Best Colleges 2021 edition.
The Forbes Magazine annual ranking of America’s Top Colleges 2021—which ranked 600 research universities, liberal arts colleges and service academies—ranked Brown 26th overall and 23rd among universities.
U.S. News & World Report ranked Brown 14th among national universities in its 2021 edition.[162] The 2021 edition also ranked Brown 1st for undergraduate teaching, 20th in Most Innovative Schools, and 18th in Best Value Schools.
Washington Monthly ranked Brown 37th in 2020 among 389 national universities in the U.S. based on its contribution to the public good, as measured by social mobility, research, and promoting public service.
For 2020, U.S. News & World Report ranks Brown 102nd globally.
In 2014, Forbes Magazine ranked Brown 7th on its list of “America’s Most Entrepreneurial Universities.” The Forbes analysis looked at the ratio of “alumni and students who have identified themselves as founders and business owners on LinkedIn” and the total number of alumni and students.
LinkedIn particularized the Forbes rankings, placing Brown third (between The Massachusetts Institute of Technology and Princeton University) among “Best Undergraduate Universities for Software Developers at Startups.” LinkedIn’s methodology involved a career-path examination of “millions of alumni profiles” in its membership database.
In 2020, U.S. News ranked Brown’s Warren Alpert Medical School the 9th most selective in the country, with an acceptance rate of 2.8 percent.
According to 2020 data from The Department of Education, the median starting salary of Brown computer science graduates was the highest in the United States.
In 2020, Brown produced the second-highest number of Fulbright winners. For the three years prior, the university produced the most Fulbright winners of any university in the nation.
Research
Brown is member of The Association of American Universities since 1933 and is classified among “R1: Doctoral Universities – Very High Research Activity”. In FY 2017, Brown spent $212.3 million on research and was ranked 103rd in the United States by total R&D expenditure by The National Science Foundation.
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