Readers Respond to the February 2025 Issue

Scientific American

20-05-2025

ORBITAL DEBRIS
The article ' How to Recycle Space Junk,' by Moriba Jah, addresses how cluttering space with detritus will have, and is having, a deleterious effect on various activities, particularly in low Earth orbit. Why not design major satellites with a small thruster that, when a satellite nears the end of its life, will push it into a trajectory that will take it into the sun? Oh, pollution of the sun, you say? Can that occur from sending a chunk of metal and silicon—even one that is boxcar-size or bigger—into a fusion furnace?
HAROLD SHAW PENOBSCOT, ME.
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Jah rightly focuses on junk in Earth orbit. Attention should also be given to junk in orbit about or on the surfaces of other bodies in the solar system, however. This is especially true of bodies that may have human-occupied facilities on their surface or in orbit about them in the future.
JAMES W. SCOTT VERNON, N.J.
JAH REPLIES: Shaw's idea is intriguing. There are a few significant challenges to consider, however. The approach would require a considerable amount of energy because Earth's orbital velocity around the sun is extremely high, and a satellite would need to be deorbited to head into our star. That is far more energy-intensive than just pushing it slightly into a lower orbit. And the trajectory would require a very precise launch window. Otherwise the satellite could just end up in a different orbit around Earth and, worse, could collide with other satellites. Moreover, although this plan could indeed have a very minimal effect on the sun's fusion process, the risks of creating a concentrated debris field in certain regions of space or inadvertently triggering an unwanted chain reaction would remain. And the environmental cost of the needed fuel could be significant. An alternative, which is currently being researched, involves using robotic 'tugboats' that would rendezvous with defunct satellites to push them into a safer orbit or to reenter Earth's atmosphere, where they would burn up. Another idea is to capture space debris with specialized nets or harpoons.
Scott is absolutely right that as human exploration and activity expand to bodies such as our moon and Mars, we must consider the potential for space debris to accumulate there as well. Such objects not only would pose a collision risk to future spacecraft but also could complicate the long-term sustainability of lunar and Martian settlements. Methods for mitigating space junk around the moon or Mars could include 'cleanup' missions using robotic systems to collect and deorbit it or even the development of infrastructure to prevent it from accumulating in the first place. New international frameworks will need to be developed to address these challenges.
REPRESENTATION IN SCIENCE
In ' Marie Curie's Hidden Network ' [Q&A], Clara Moskowitz talks to author Dava Sobel about her book regarding Curie and the women who worked in the famous scientist's laboratory. In the discussion, Sobel emphasizes that Curie's approach to recruiting female scientists was characterized by a neutral stance—that 'she had nothing against hiring [women].'
When observing videos of enthusiastic groups in technical roles, I often find myself morbidly counting the people of color. Women have become relatively better represented in science, but people of color remain glaringly less so. Ideally, candidates are chosen based on résumés and credentials. But studies consistently show that résumés with names suggesting people of color receive significantly less interest than otherwise identical ones. This effect is often demonstrably subconscious, suggesting that to be selected, such individuals need to stand out—echoing Curie, who went on to win two Nobel Prizes, defying stereotypes.
As we navigate into an uncertain future, let us take a moment to recognize that it required a scientist of Madame Curie's extraordinary caliber to remind us of the essential work that is still needed to harness the full potential of all available human capital.
K. CYRUS ROBINSON TAMPA, FLA.
TEEN BRAIN DEVELOPMENT
' Growing the Adolescent Mind,' by Mary Helen Immordino-Yang, identifies adolescence as a time of opportunity for growth. 'Transcendent thinking' is used throughout the article to describe the ability to 'muse in an abstract way' about a given situation, including by considering different cognitive perspectives. This phrasing is misleading. 'Transcendent thinking' usually refers to mystical or 'peak' experiences, which are ineffable, holistic, and outside of time and space.
Immordino-Yang also claims a cause-and-effect process in which reflective, emotional thinking makes brain networks communicate more effectively. It could instead be that changing brain connections allow for the expansion of reflective and emotional thinking. The author notes neuroscientist Antonio Damasio's work with a patient known as EVR, whose case involved the latter causation: as described in the article, brain surgery changed EVR's social and emotional intelligence.
Encouraging adolescents to see the bigger picture is important, but we must work with their current brain capacity.
FREDERICK TRAVIS FAIRFIELD, IOWA
IMMORDINO-YANG REPLIES: Travis points out a common misunderstanding. My colleagues and I coined 'transcendent thinking' to describe thinking that is abstract and 'transcends,' or 'moves beyond,' the concrete here and now. 'Transcendental' refers to mystical or out-of-this-world experiences (although some have used 'transcendent' this way).
It is also a good point that we cannot prove that teens' transcendent thinking causes brain development. It cannot be only that changing brain connections allows this thinking to occur, however. In my team's study of teenagers in Los Angeles, the level of transcendent thinking at the beginning of the study predicts future brain development, irrespective of the teens' brain development at the start. The level of transcendent thinking also does not correlate with brain maturation at the study's start. Our data are consistent with an at least partly causal explanation, and we are now working to demonstrate this conclusively at the University of Southern California's Center for Affective Neuroscience, Development, Learning and Education (https://candle.usc.edu).
A SPLOTCH, A BLOTCH
It's interesting that the February issue has two feature articles about 'blobs': ' Anatomy of a Supernova,' by Clara Moskowitz, and ' A New Understanding of the Cell,' by Philip Ball. But the two types of blobs couldn't be more different and are many orders of magnitude different in size.
CHRIS LANDRY HUDSON, N.H.
ERRATA
' Redefining Time,' by Jay Bennett [March], should have given the full English name of BIPM as the International Bureau of Weights and Measures.
In ' The Missing Planets,' by Dakotah Tyler [March], the deck summarizing the article should have said that exoplanet demographics reveal a puzzling lack of worlds in a certain size range.