Steven A. Hauck

The recent U.S. executive order “Restoring Gold Standard Science” poses a significant threat to the U.S. national economy and security. The order replaces the scientific experts who lead U.S. governmental scientific organizations with non‐scientific political appointees who would have the power to decide what science could and could not be published. In doing so, the executive order threatens to reverse more than 80 years of scientific advancements that have given the U.S. its world‐leading military, technology, and economy. The justifications provided in the executive order for this change in policy are false or misleading in their assessment and representation of the current state of U.S. scientific scholarship. Hypocritical in its aims, the executive order claims to promote integrity in science while at the same time calling to remove the “Framework for Federal Scientific Integrity Policy and Practice” that currently ensure veracity and credibility in science. The executive order is also unconstitutional, threatening to take away the First Amendment rights of scientists by punishing them if they publish truthful and accurate science that is contrary to the administration's political agenda. Such censorship of scientists has been attempted by failed governments of the past such as Nazi Germany, the Soviet Union, and early communist China, always with disastrous consequences for their citizens. “Restoring Gold Standard Science” needs to be rescinded to avoid catastrophic consequences for the U.S. economy and national security.

Addressing global challenges and advancing knowledge in the Earth and space sciences requires an equitable, diverse, and inclusive scholarly community where researchers must be freely able to conduct, collaborate on, share, review, and discuss their research on important economic and societal topics such as climate change. The current Executive Orders in the United States focus on censoring research and researchers by banning specific words, removing access to data sets, or by restricting what type of research can be funded or published, therefore compromising the knowledge that researchers are able to produce. As Editors‐in‐Chief of AGU publications we stand by our mission to support the publication of evidence‐based, rigorously vetted research without political pressure. Collectively, our peer‐reviewed journals and books provide inclusive publication outlets for the global research community to advance Earth and space sciences and to strengthen the public's trust in scientific evidence.

Mercury holds valuable clues to the distribution of elements at the birth of the solar system and how planets form and evolve in close proximity to their host stars. This Mercury Lander mission concept returns in situ measurements that address fundamental science questions raised by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission’s pioneering exploration of Mercury. Such measurements are needed to understand Mercury's unique mineralogy and geochemistry, characterize the proportionally massive core's structure, measure the planet's active and ancient magnetic fields at the surface, investigate the processes that alter the surface and produce the exosphere, and provide ground truth for remote data sets. The mission concept achieves one full Mercury year (∼88 Earth days) of surface operations with an 11-instrument, high-heritage payload delivered to a landing site within Mercury's widely distributed low-reflectance material, and it addresses science goals encompassing geochemistry, geophysics, the Mercury space environment, and geology. The spacecraft launches in 2035, and the four-stage flight system uses a solar electric propulsion cruise stage to reach Mercury in 2045. Landing is at dusk to meet thermal requirements, permitting ∼30 hr of sunlight for initial observations. The radioisotope-powered lander continues operations through the Mercury night. Direct-to-Earth communication is possible for the initial 3 weeks of landed operations, drops out for 6 weeks, and resumes for the final month. Thermal conditions exceed lander operating temperatures shortly after sunrise, ending operations. Approximately 11 GB of data are returned to Earth. The cost estimate demonstrates that a Mercury Lander mission is feasible and compelling as a New Frontiers–class mission.

Science is at its best when shared widely both within the scientific community and to the broader public. To maintain trust in science while simultaneously maximizing openness, it is important that every paper is carefully vetted. For this we rely on many volunteers, especially our peer reviewers. Their work is key for maintaining the integrity of scientific journals and to ensure the highest standards of scientific rigor. Reviewers verify that the assumptions, the methods, and the inferences made in our papers are sound. Many spend hours going over derivations, analyses, and evaluating the novelty and significance of the submitted manuscript. In 2019, JGR Planets benefited from 901 reviews provided by 584 unique reviewers. On behalf of the entire editorial board of JGR Planets and the entire planetary science community, we want to express here our most heartfelt gratitude to all of you. Thank you!

In 2016, JGR: Planets became the first AGU journal to begin accepting plain language summaries as a component of research and review articles. Authors began widely participating in this new approach to sharing planetary science in clear language with growth from 18% to 52% of published articles having a summary from the first to last quarters of 2017. In 2018, JGR: Planets joined several other AGU journals in making a plain language summary an expectation of all papers. Plain language summaries are an opportunity to make the rationale for, relevance of, and results from our work clear to a broad audience including students, science journalists, funders, and colleagues outside our specialty, among others. As adoption of and familiarity with, plain language summaries expands the impact of our work within our community and our society will grow too.

A new special collection in JGR: Planets explores how ice has played a key role in the development of the landscape on the surface of Ceres.

The outgoing Editor-in-Chief of JGR: Planets reflects on the journal’s role serving the planetary science community and expresses appreciation for all those who contribute to its success.

Peer review is an act of serving the community. Each peer review leads to sharper, more accurate, more impactful science, and clearer communication. Reviews from independent colleagues help bring the strengths and opportunities for improvement in scientific work into focus. Each year in planetary science, new ideas and places are explored; new understanding of our planet, its neighbors, and distant exoplanets is uncovered. Ensuring that the lessons of those discoveries can lead to new breakthroughs rests on the accuracy and accessibility of science we share. In 2018, we were humbled by the 756 peer reviews from 460 individuals that JGR: Planets received. Thank you for your efforts, your insights, and your service on behalf of the planetary science community.

Geodetic analysis of radio tracking measurements of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft while in orbit about Mercury has yielded new estimates for the planet's gravity field, tidal Love number, and pole coordinates. The derived right ascension (α = 281.0082° ± 0.0009°; all uncertainties are 3 standard deviations) and declination (δ = 61.4164° ± 0.0003°) of the spin pole place Mercury in the Cassini state. Confirmation of the equilibrium state with an estimated mean (whole planet) obliquity ϵ of 1.968 ± 0.027 arcmin enables the confident determination of the planet's normalized polar moment of inertia (0.333 ± 0.005), which indicates a high degree of internal differentiation. Internal structure models generated by a Markov Chain Monte Carlo process and consistent with the geodetic constraints possess a solid inner core with a radius (r_ic) between 0.3 and 0.7 that of the outer core (r_oc).

NASA's MESSENGER spacecraft orbited Mercury from 2011 to 2015 and has provided new insights into the interior of the innermost planet. Mercury has a large metallic core ~2,000 km in radius covered by a thin layer of rock only ~420 km thick. Furthermore, a surprisingly large fraction of this outer layer was produced by melting of deeper rocks, forming a light crust ~35 km thick. The core is now known to produce a magnetic field that has intriguing similarities and differences compared to Earth's field. Some rocks near the surface are magnetized, and the strongest magnetizations are likely to be >3.5 billion years old. This new understanding of Mercury's interior is helping reveal how rocky planets operate.