Robotic spacecraft: 250px|right|thumb|An artist's interpretation of the [[MESSENGER spacecraft at Mercury]]Shiva crater: The Shiva Crater is a geologic structure, which is hypothesized by Sankar ChatterjeeChatterjee, S. (1997) Multiple impacts at the KT boundary and the death of the dinosaurs.Ganymede (moon)Christmas on the International Space Station: Christmas on the International Space Station covers the celebration of Christmas on the International Space Station. Christmas is a seasonal religious celebration, and is celebrated each year by the International Space Station crew, their families, and ground-staff.Closed ecological systemMars Orbiter Laser Altimeter: [Martian hemispheres by MOLA.jpg|right|thumb|260px|MOLA topographic images of the two hemispheres of Mars.Mary Voytek: Dr. Mary A.Interstellar cloud: Interstellar cloud is the generic name given to an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium.Saturn A-1: Saturn A-1, studied in 1959, was projected to be the first version of Saturn I and was to be used if necessary before the S-IV liquid hydrogen second stage became available. The first stage, proposed for the Juno V rocket, but finally used for the first Saturn rocket, would propel the Saturn A-1 into space, with the first stage of a Titan I missile continuing the flight and finally, a Centaur C high-energy double-engine third stage could perform a small burn to send a payload into its final orbit, or it can perform a big burn to take a payload out of Earth orbit to other planets.Chondrule: Chondrules in the chondrite Grassland|200px|thumb|Chondrules in the chondrite Grassland. A millimeter scale is shown.Protein quaternary structure: In biochemistry, quaternary structure is the number and arrangement of multiple folded protein subunits in a multi-subunit complex. It includes organisations from simple dimers to large homooligomers and complexes with defined or variable numbers of subunits.Moonlight: [22-12-47-moonlight.jpg|thumb|A photograph taken by moonlight with an exposure time of fifty minutes.List of Antarctic ice streams: This is a list of Antarctic ice streams.NebulaUltra-high-energy cosmic ray: In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray particle with a kinetic energy greater than eV, far beyond both its rest mass and energies typical of other cosmic ray particles.Stratosphere: The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down.Gijs Kuenen: Johannes Gijsbrecht Kuenen (born 9 December 1940, Heemstede) is a Dutch microbiologist who is professor emeritus at the Delft University of Technology and a visiting scientist at the University of Southern California. His research is influenced by, and a contribution to, the scientific tradition of the Delft School of Microbiology.Micro-g environment: The term micro-g environment (also µg, often referred to by the term microgravity) is more or less a synonym of weightlessness and zero-G, but indicates that g-forces are not quite zero, just very small. The symbol for microgravity, µg, was used on the insignias of Space Shuttle flights STS-87 and STS-107, because these flights were devoted to microgravity research in low Earth orbit.List of largest volcanic eruptions: In a volcanic eruption, lava, tephra (volcanic bombs, lapilli, and ash), and various gases are expelled from a volcanic vent or fissure. While many eruptions only pose dangers to the immediately surrounding area, Earth's largest eruptions can have a major regional or even global impact, with some affecting the climate and contributing to mass extinctions.List of Gemini astronauts: The following astronauts flew on the 10 manned Gemini missions:Bacillus alcalophilus: Bacillus alcalophilus is a Gram-positive, rod-shaped species of bacteria. Likely strains of this species have been isolated from highly alkaline waste water.Bacterial spore: A bacterial spore is a spore or spore-like structure produced by bacteria. These include endospores, Akinetes, and spores produced by Actinobacteria and Azotobacter.Marine fungi: Marine fungi are species of fungi that live in marine or estuarine environments. They are not a taxonomic group but share a common habitat.Fujiyama (roller coaster)Corynebacterium amycolatum: Corynebacterium amycolatum is a Gram-positive, nonspore-forming, aerobic or facultatively anaerobic bacillus capable of fermentation with propionic acid as the major end product of its glucose metabolism. One of its best known relatives is Corynebacterium diphtheriae, the causative agent of diphtheria.Clavibacter michiganensis: Clavibacter michiganensis is an aerobic non-sporulating Gram-positive plant pathogenic actinomycete that currently constitutes the only species within the genus Clavibacter. The other former Clavibacter species have been reclassified to genera Leifsonia, Rathayibacter and Curtobacterium.Exogenous bacteria: Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. They exist in aquatic and terrestrial environments, as well as the atmosphere.