Mae Jemison, Jeanette J. Epps, Joan Higginbotham, Yvonne Cagle, Stephanie Wilson, and finally Nichelle Nichols, she is not an astronaut, but she starred in Star Trek, becoming inspiration for a lot of African American women to become astronauts and astrophysicists
On Aug. 3, 2004, NASA’s Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft began a seven-year journey, spiraling through the inner solar system to Mercury. One year after launch, the spacecraft zipped around Earth, getting an orbit correction from Earth’s gravity and getting a chance to test its instruments by observing its home planet.
This image is a view of South America and portions of North America and Africa from the Mercury Dual Imaging System’s wide-angle camera aboard MESSENGER. The wide-angle camera records light at eleven different wavelengths, including visible and infrared light. Combining blue, red, and green light results in a true-color image from the observations. The image substitutes infrared light for blue light in the three-band combination. The resulting image is crisper than the natural color version because our atmosphere scatters blue light. Infrared light, however, passes through the atmosphere with relatively little scattering and allows a clearer view. That wavelength substitution makes plants appear red. Why? Plants reflect near-infrared light more strongly than either red or green, and in this band combination, near-infrared is assigned to look red.
Apart from getting a clearer image, the substitution reveals more information than natural color. Healthy plants reflect more near-infrared light than stressed plants, so bright red indicates dense, growing foliage. For this reason, biologists and ecologists occasionally use infrared cameras to photograph forests.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Caption: Holli Riebeek
Mars’ northern-most sand dunes are beginning to emerge from their winter cover of seasonal carbon dioxide (dry) ice. Dark, bare south-facing slopes are soaking up the warmth of the sun.
The steep lee sides of the dunes are also ice-free along the crest, allowing sand to slide down the dune. Dark splotches are places where ice cracked earlier in spring, releasing sand. Soon the dunes will be completely bare and all signs of spring activity will be gone.
This image was acquired by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter on Jan. 16, 2014. The University of Arizona, Tucson, operates the HiRISE camera, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for the NASA Science Mission Directorate, Washington.
Image Credit: NASA/JPL-Caltech/Univ. of Arizona
Caption: Candy Hansen
Interest in photochemical synthesis has been motivated in part by the realization that sunlight is effectively an inexhaustible energy source.Chemists have also long recognized distinctive patterns of reactivity that are uniquely accessible via photochemical activation. However, most simple organic molecules absorb only ultraviolet (UV) light and cannot be activated by the visible wavelengths that comprise most of the solar energy that reaches Earth’s surface. Consequently, organic photochemistry has generally required the use of UV light sources.
Over the past several years, there has been a resurgence of interest in synthetic photochemistry, based on the recognition that the transition metal chromophores that have been so productively exploited in the design of technologies for solar energy conversion can also convert visible light energy into useful chemical potential for synthetic purposes. Visible light enables productive photoreactions of compounds possessing weak bonds that are sensitive toward UV photodegradation. Furthermore, visible light photoreactions can be conducted by using essentially any source of white light, including sunlight, which obviates the need for specialized UV photoreactors. This feature has expanded the accessibility of photochemical reactions to a broader range of synthetic organic chemists. A variety of reaction types have now been shown to be amenable to visible light photocatalysis via photoinduced electron transfer to or from the transition metal chromophore, as well as energy-transfer processes. The predictable reactivity of the intermediates generated and the tolerance of the reaction conditions to a wide range of functional groups have enabled the application of these reactions to the synthesis of increasingly complex target molecules.
This general strategy for the use of visible light in organic synthesis is already being adopted by a growing community of synthetic chemists. Much of the current research in this emerging area is geared toward the discovery of photochemical solutions for increasingly ambitious synthetic goals. Visible light photocatalysis is also attracting the attention of researchers in chemical biology, materials science, and drug discovery, who recognize that these reactions offer opportunities for innovation in areas beyond traditional organic synthesis. The long-term goals of this emerging area are to continue to improve efficiency and synthetic utility and to realize the long-standing goal of performing chemical synthesis using the sun.
Jules Verne’s travellers in his 1864 science fiction novel Journey to the Centre of the Earth encountered “crystals… like globes of light”. One hundred and fifty years later, the study of crystals is poised to shine new light on the deep Earth.
The journey to our planet’s centre began a century ago when William Henry Bragg and his son, William Lawrence, used X-ray diffraction to reveal the atomic configuration of common minerals such as halite, diamond, fluorite and calcite. Decades of challenging experimental work to unravel how the structures of such minerals are altered by the extreme pressures and temperatures found in the deep Earth culminated in 2004 when researchers discovered that the main mineral of the lower mantle, iron-bearing magnesium silicate ((Mg,Fe)SiO3) perovskite, transforms to a compact configuration known as post-perovskite at conditions similar to those at the core–mantle boundary.
Post-perovskite’s characteristics explain many of the unusual seismic properties of a distinct 200-kilometre-thick zone at the base of the mantle, a layer that might be a remnant of Earth’s formation. This region plays a key but poorly understood part in the thermal structure of the planet.
Ten years on from its discovery, the post-perovskite story remains incomplete. The roles of crystal deformation, chemical variation and temperature in controlling the deep mantle’s characteristics are yet to be fully understood. And work on the iron alloys that make up the core is only just beginning. New crystallographic techniques will usher in a deeper understanding of crystal structures and their connection to our planet’s architecture, composition and evolution.
Illustration by Édouard Riou from Jules Verne’s Journey to the Centre of the Earth
On Feb. 19, 2014 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite flew over the Great Lakes and captured this striking false-colored image of the heavily frozen Great Lakes – one of the hardest freeze-ups in four decades.
According to the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory (GLERL), ice cover on North America’s Great Lakes peaked at 88.42% on Feb. 12-13 – a percentage not recorded since 1994. The ice extent has surpassed 80% just five times in four decades. The average maximum ice extent since 1973 is just over 50%.
Unusually cold temperatures in the first two months of the year, especially in January, are responsible for the high ice coverage. Very cold air blowing over the surface of the water removes heat from the water at the surface. When the surface temperature drops to freezing, a thin layer of surface ice begins to form. Once ice formation begins, persistently cold temperatures, with or without wind, is the major factor in thickening ice.
This false-color image uses a combination of shortwave infrared, near infrared and red (MODIS bands 7,2,1) to help distinguish ice from snow, water and clouds. Open, unfrozen water appears inky blue-black. Ice is pale blue, with thicker ice appearing brighter and thin, melting ice appearing a darker true-blue. Snow appears blue-green. Clouds are white to blue-green, with the colder or icy clouds appearing blue-green to blue.
Image Credit: NASA/Jeff Schmaltz, MODIS Land Rapid Response Team, NASA GSFC
The Stories That Galaxies Tell on @NautilusMag
The biggest merger to ever hit these parts is coming—a union that promises to be more tumultuous than that of Richard Burton and Elizabeth Taylor, offer more star power than Brangelina, and deliver more jet propulsion than the new American Airlines–US Airways conglomerate. We’re talking about the coming together of the Milky Way galaxy and its nearest large neighbor, Andromeda, in a collision that scientists now deem inevitable. This celestial amalgamation will begin in about 4 billion years and finish within another 2 billion, producing a new, larger elliptical galaxy in place of the two spirals that originally conjoined.
Illustration by Mikel Jaso
On Feb. 24, 2014, the sun emitted a significant solar flare, peaking at 7:49 p.m. EST. NASA’s Solar Dynamics Observatory (SDO), which keeps a constant watch on the sun, captured images of the event. These SDO images from 7:25 p.m. EST on Feb. 24 show the first moments of this X-class flare in different wavelengths of light — seen as the bright spot that appears on the left limb of the sun. Hot solar material can be seen hovering above the active region in the sun’s atmosphere, the corona.
Solar flares are powerful bursts of radiation, appearing as giant flashes of light in the SDO images. Harmful radiation from a flare cannot pass through Earth’s atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel.
Image Credit: NASA/SDO