Commercial Resupply Services ( CRS ) are a series of flights awarded by NASA for the delivery of cargo and supplies to the International Space Station (ISS) on commercially operated spacecraft.
98-554: SpaceX CRS-21 , also known as SpX-21 , was a Commercial Resupply Service mission to the International Space Station which launched on 6 December 2020. The mission was contracted by NASA and was flown by SpaceX using a Cargo Dragon 2 . This was the first flight for SpaceX under NASA's CRS Phase 2 contract awarded in January 2016. This was also the first Cargo Dragon of the new Dragon 2 variant, as well as
196-406: A nucleus and rarely harbour membrane -bound organelles . Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved from an ancient common ancestor . These evolutionary domains are called Bacteria and Archaea . The word bacteria
294-543: A potential difference analogous to a battery. The general lack of internal membranes in bacteria means these reactions, such as electron transport , occur across the cell membrane between the cytoplasm and the outside of the cell or periplasm . However, in many photosynthetic bacteria, the plasma membrane is highly folded and fills most of the cell with layers of light-gathering membrane. These light-gathering complexes may even form lipid-enclosed structures called chlorosomes in green sulfur bacteria . Bacteria do not have
392-404: A terminal electron acceptor in a redox reaction . Chemotrophs are further divided by the types of compounds they use to transfer electrons. Bacteria that derive electrons from inorganic compounds such as hydrogen, carbon monoxide , or ammonia are called lithotrophs , while those that use organic compounds are called organotrophs . Still, more specifically, aerobic organisms use oxygen as
490-466: A Dragon capsule's ability to remain in orbit, receive and respond to ground commands, and communicate with NASA's Tracking and Data Relay Satellite System . On 15 August 2011, SpaceX announced that NASA had combined the objectives of the COTS Demo Flight 2 and following Flight 3 into a single mission. The rescoped COTS Demo Flight 2 successfully launched on 22 May 2012, delivering cargo to
588-744: A bacterial strain. However, liquid growth media are used when the measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms. Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led
686-533: A combined, not-to-exceed value of $ 14 billion. NASA officials explained that selecting three companies rather than two for CRS-2 increases cargo capabilities and ensures more redundancy in the event of a contractor failure or schedule delay. The CRS-2 flights commenced in November 2019 with the launch of Cygnus NG-12 mission. Inside-cargo is typically transported to and from the space station in "the form factor of single Cargo Transfer Bag Equivalent (CTBE) [which
784-517: A competitive range determination to remove Boeing and Lockheed Martin. Orbital ATK (later purchased by Northrop Grumman), Sierra Nevada, and SpaceX were awarded CRS-2 contracts in January 2016 with initial task orders awarded in June 2016. Each of the three companies is guaranteed at least six cargo missions under the CRS-2 contract. As of December 2017, NASA had awarded $ 2.6 billion on three contracts with
882-424: A disorganised slime layer of extracellular polymeric substances to a highly structured capsule . These structures can protect cells from engulfment by eukaryotic cells such as macrophages (part of the human immune system ). They can also act as antigens and be involved in cell recognition, as well as aiding attachment to surfaces and the formation of biofilms. The assembly of these extracellular structures
980-413: A few micrometres in thickness to up to half a metre in depth, and may contain multiple species of bacteria, protists and archaea. Bacteria living in biofilms display a complex arrangement of cells and extracellular components, forming secondary structures, such as microcolonies , through which there are networks of channels to enable better diffusion of nutrients. In natural environments, such as soil or
1078-415: A few species are visible to the unaided eye—for example, Thiomargarita namibiensis is up to half a millimetre long, Epulopiscium fishelsoni reaches 0.7 mm, and Thiomargarita magnifica can reach even 2 cm in length, which is 50 times larger than other known bacteria. Among the smallest bacteria are members of the genus Mycoplasma , which measure only 0.3 micrometres, as small as
SECTION 10
#17327905936251176-426: A fixed size and then reproduce through binary fission , a form of asexual reproduction . Under optimal conditions, bacteria can grow and divide extremely rapidly, and some bacterial populations can double as quickly as every 17 minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse
1274-418: A large domain of prokaryotic microorganisms . Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth , and are present in most of its habitats . Bacteria inhabit the air, soil, water, acidic hot springs , radioactive waste , and the deep biosphere of Earth's crust . Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and
1372-408: A membrane-bound nucleus, and their genetic material is typically a single circular bacterial chromosome of DNA located in the cytoplasm in an irregularly shaped body called the nucleoid . The nucleoid contains the chromosome with its associated proteins and RNA . Like all other organisms , bacteria contain ribosomes for the production of proteins, but the structure of the bacterial ribosome
1470-528: A particular organism or group of organisms ( syntrophy ). Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase , a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. The second phase of growth
1568-415: A process called transformation . Many bacteria can naturally take up DNA from the environment, while others must be chemically altered in order to induce them to take up DNA. The development of competence in nature is usually associated with stressful environmental conditions and seems to be an adaptation for facilitating repair of DNA damage in recipient cells. Second, bacteriophages can integrate into
1666-510: A result Russia's invasion of Ukraine, Northrop Grumman was left with only two remaining Antares 230+ launch vehicles which were used for the CRS NG-18 and CRS NG-19 missions. Northrop Grumman acquired three flights from SpaceX with the Falcon 9 rocket while a replacement first stage and its engine are developed for its Antares 330 rocket. Northrop Grumman plans to launch further missions using
1764-425: A single continuous stretch of DNA. Although several different types of introns do exist in bacteria, these are much rarer than in eukaryotes. Bacteria, as asexual organisms, inherit an identical copy of the parent's genome and are clonal . However, all bacteria can evolve by selection on changes to their genetic material DNA caused by genetic recombination or mutations . Mutations arise from errors made during
1862-427: A single linear chromosome, while some Vibrio species contain more than one chromosome. Some bacteria contain plasmids , small extra-chromosomal molecules of DNA that may contain genes for various useful functions such as antibiotic resistance , metabolic capabilities, or various virulence factors . Bacteria genomes usually encode a few hundred to a few thousand genes. The genes in bacterial genomes are usually
1960-649: A source of electrons and a substrate for carbon anabolism . In many ways, bacterial metabolism provides traits that are useful for ecological stability and for human society. For example, diazotrophs have the ability to fix nitrogen gas using the enzyme nitrogenase . This trait, which can be found in bacteria of most metabolic types listed above, leads to the ecologically important processes of denitrification , sulfate reduction , and acetogenesis , respectively. Bacterial metabolic processes are important drivers in biological responses to pollution ; for example, sulfate-reducing bacteria are largely responsible for
2058-797: A thick peptidoglycan cell wall like a Gram-positive bacterium, but also a second outer layer of lipids. In many bacteria, an S-layer of rigidly arrayed protein molecules covers the outside of the cell. This layer provides chemical and physical protection for the cell surface and can act as a macromolecular diffusion barrier . S-layers have diverse functions and are known to act as virulence factors in Campylobacter species and contain surface enzymes in Bacillus stearothermophilus . Flagella are rigid protein structures, about 20 nanometres in diameter and up to 20 micrometres in length, that are used for motility . Flagella are driven by
SECTION 20
#17327905936252156-417: A three- dimensional random walk . Bacterial species differ in the number and arrangement of flagella on their surface; some have a single flagellum ( monotrichous ), a flagellum at each end ( amphitrichous ), clusters of flagella at the poles of the cell ( lophotrichous ), while others have flagella distributed over the entire surface of the cell ( peritrichous ). The flagella of a group of bacteria,
2254-584: A variety of other research including studies on how space conditions affect the interaction between microbes and minerals. Beginning with the CRS-2 contract, NASA reports major hardware (failed or expended hardware for diagnostic assessment, refurbishment, repair, or no longer needed) returning from the International Space Station. The CRS-21 mission returned 2,002 kg (4,414 lb) of cargo to Earth. This cargo included: Treadmill Data Avionics Unit : Failed avionics unit that supports
2352-414: Is a continuation of a previous experiment. This experiment will study cardiomyocytes in human heart tissue and its reaction to a zero-g environment. NASA Astronaut Kate Rubins was present for the experiment on station a few years ago, and she said that, paraphrased, few things on station make her gasp, but this is one thing that does. Subsa-Brains studies the effects of micrometeorites and space junk and
2450-465: Is a protein crystallization experiment by the American pharmaceutical company Bristol Myers Squibb . NASA astronauts will study the crystallization of monoclonal antibodies in space, with the aim of improving drug formulation and delivery for patients on Earth. Monoclonal antibodies are lab-created proteins designed to interact with specific targets, called antigens . Monoclonal antibodies are used in
2548-663: Is a test of the system for white blood cell testing on the Moon and Mars. The systems were developed under Earth's gravity, and still need to be tested in zero-g's. The Brain Organoid experiment is a continuation of the first Brain Organoid experiment. Its goal is to validate the first round of experiments and to continue the research recorded during those first tests. The program studies the early developed human brain, its movements in microgravity, and can help address and create better models of neurodegenerative disorders. Cardinal Heart
2646-480: Is caused by a toxin released by the bacteria that grow from the spores. Clostridioides difficile infection , a common problem in healthcare settings, is caused by spore-forming bacteria. Bacteria exhibit an extremely wide variety of metabolic types. The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy , but these traits often do not correspond with modern genetic classifications. Bacterial metabolism
2744-412: Is classified into nutritional groups on the basis of three major criteria: the source of energy , the electron donors used, and the source of carbon used for growth. Phototrophic bacteria derive energy from light using photosynthesis , while chemotrophic bacteria breaking down chemical compounds through oxidation , driving metabolism by transferring electrons from a given electron donor to
2842-613: Is considerably less. CRS-2 launches commenced in 2019 and will extend to at least 2024. Three more CRS-2 missions for Dragon 2 covering up to CRS-29 were announced in December 2020. When NASA issued the Commercial Resupply Services phase 2 (CRS-2) request for proposal (RFP) in September 2014, it received interest from five companies: Lockheed Martin, Boeing, Orbital ATK, Sierra Nevada, and SpaceX. NASA made
2940-536: Is dependent on bacterial secretion systems . These transfer proteins from the cytoplasm into the periplasm or into the environment around the cell. Many types of secretion systems are known and these structures are often essential for the virulence of pathogens, so are intensively studied. Some genera of Gram-positive bacteria, such as Bacillus , Clostridium , Sporohalobacter , Anaerobacter , and Heliobacterium , can form highly resistant, dormant structures called endospores . Endospores develop within
3038-534: Is determined by the bacterial cell wall and cytoskeleton and is important because it can influence the ability of bacteria to acquire nutrients, attach to surfaces, swim through liquids and escape predators . Multicellularity . Most bacterial species exist as single cells; others associate in characteristic patterns: Neisseria forms diploids (pairs), streptococci form chains, and staphylococci group together in "bunch of grapes" clusters. Bacteria can also group to form larger multicellular structures, such as
SpaceX CRS-21 - Misplaced Pages Continue
3136-441: Is different from that of eukaryotes and archaea. Some bacteria produce intracellular nutrient storage granules, such as glycogen , polyphosphate , sulfur or polyhydroxyalkanoates . Bacteria such as the photosynthetic cyanobacteria , produce internal gas vacuoles , which they use to regulate their buoyancy, allowing them to move up or down into water layers with different light intensities and nutrient levels. Around
3234-414: Is essential to the survival of many bacteria, and the antibiotic penicillin (produced by a fungus called Penicillium ) is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan. There are broadly speaking two different types of cell wall in bacteria, that classify bacteria into Gram-positive bacteria and Gram-negative bacteria . The names originate from the reaction of cells to
3332-659: Is intended to help inform robustness of a similar valve design on the Orion spacecraft . Commercial Resupply Services The first phase of CRS contracts (CRS-1) were signed in 2008 and awarded $ 1.6 billion to SpaceX for twelve Dragon 1 and $ 1.9 billion to Orbital Sciences for eight Cygnus flights, covering deliveries to 2016. The first operational resupply missions were flown by SpaceX in 2012 ( CRS SpX-1 ) and Orbital in 2014 ( CRS Orb-1 ). In 2015, NASA extended CRS-1 to twenty flights for SpaceX and twelve flights for Orbital ATK . A second phase of contracts ( CRS-2 )
3430-529: Is made of about 20 proteins, with approximately another 30 proteins required for its regulation and assembly. The flagellum is a rotating structure driven by a reversible motor at the base that uses the electrochemical gradient across the membrane for power. Bacteria can use flagella in different ways to generate different kinds of movement. Many bacteria (such as E. coli ) have two distinct modes of movement: forward movement (swimming) and tumbling. The tumbling allows them to reorient and makes their movement
3528-468: Is made primarily of phospholipids . This membrane encloses the contents of the cell and acts as a barrier to hold nutrients, proteins and other essential components of the cytoplasm within the cell. Unlike eukaryotic cells , bacteria usually lack large membrane-bound structures in their cytoplasm such as a nucleus , mitochondria , chloroplasts and the other organelles present in eukaryotic cells. However, some bacteria have protein-bound organelles in
3626-496: Is motile in liquid or solid media. Several Listeria and Shigella species move inside host cells by usurping the cytoskeleton , which is normally used to move organelles inside the cell. By promoting actin polymerisation at one pole of their cells, they can form a kind of tail that pushes them through the host cell's cytoplasm. A few bacteria have chemical systems that generate light. This bioluminescence often occurs in bacteria that live in association with fish, and
3724-447: Is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair , antioxidant metabolism and nutrient transport . The final phase is the death phase where
3822-440: Is the logarithmic phase , also known as the exponential phase. The log phase is marked by rapid exponential growth . The rate at which cells grow during this phase is known as the growth rate ( k ), and the time it takes the cells to double is known as the generation time ( g ). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth
3920-694: Is the plural of the Neo-Latin bacterium , which is the Latinisation of the Ancient Greek βακτήριον ( baktḗrion ), the diminutive of βακτηρία ( baktēría ), meaning "staff, cane", because the first ones to be discovered were rod-shaped . The ancestors of bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, about 4 billion years ago. For about 3 billion years, most organisms were microscopic, and bacteria and archaea were
4018-632: Is the prime contractor, with Thales Alenia Space manufacturing the pressurized shell and Boeing providing the berthing mechanism. It is the second commercial module of the ISS, after the Bigelow Expandable Activity Module (BEAM), which was attached to the ISS in April 2016 and is expected to stay at the ISS until at least 2028. The Bishop Airlock began construction in 2015, and was berthed to Tranquility on 19 December 2020 by
SpaceX CRS-21 - Misplaced Pages Continue
4116-470: Is the] unit for size of bag used to transport cargo from visiting vehicles , such as SpaceX Dragon , Northrop Grumman Cygnus , or JAXA H-II Transfer Vehicle (HTV). The bags are sized at 48 cm × 41 cm × 23 cm (19 in × 16.25 in × 9 in) and limited in transport mass to 27 kg (60 lb) each. CTBE units are also used to price, and charge, commercial users of US Orbital Segment stowage space. As
4214-547: The Automated Transfer Vehicle , to be jointly developed with Thales Alenia Space . Three companies were awarded contracts on January 14, 2016. Sierra Nevada Corporation 's Dream Chaser , the SpaceX Dragon 2 , and Orbital ATK Cygnus were selected, each for a minimum of six launches. The maximum potential value of all the contracts was indicated to be $ 14 billion, but the minimum value
4312-528: The Canadarm2 . BioAsteroid is an experiment designed to test the infrastructure and tools needed for asteroid, lunar, and Martian rock biomining . It will use microorganisms (the bacterium S. desiccabilis and the fungus P. simplicissimum ) to extract metals from L- chondrite , testing the possibility to use this technique to obtain resources that will allow long-term and long-distance human space exploration and extraterrestrial settlements. Hemocue
4410-629: The Cargo Dragon . The CRS-21 mission carries 2,972 kg (6,552 lb) of cargo to ISS. Nanoracks Bishop Airlock , formerly known as Bishop Airlock Module, is a payload airlock attached to the Tranquility module of the ISS, commercially developed and operated by Nanoracks . The Bishop Airlock provides five times the satellite deployment volume previously available, when the Japanese Kibō airlock served that role alone. Nanoracks
4508-472: The Gram stain , a long-standing test for the classification of bacterial species. Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids . In contrast, Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins . Most bacteria have
4606-624: The fixation of nitrogen from the atmosphere . The nutrient cycle includes the decomposition of dead bodies ; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps , extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane , to energy. Bacteria also live in mutualistic , commensal and parasitic relationships with plants and animals. Most bacteria have not been characterised and there are many species that cannot be grown in
4704-444: The spirochaetes , are found between two membranes in the periplasmic space. They have a distinctive helical body that twists about as it moves. Two other types of bacterial motion are called twitching motility that relies on a structure called the type IV pilus , and gliding motility , that uses other mechanisms. In twitching motility, the rod-like pilus extends out from the cell, binds some substrate, and then retracts, pulling
4802-551: The vacuum and radiation of outer space , leading to the possibility that bacteria could be distributed throughout the Universe by space dust , meteoroids , asteroids , comets , planetoids , or directed panspermia . Endospore-forming bacteria can cause disease; for example, anthrax can be contracted by the inhalation of Bacillus anthracis endospores, and contamination of deep puncture wounds with Clostridium tetani endospores causes tetanus , which, like botulism ,
4900-698: The 2000s funding was authorized for the Commercial Orbital Transportation Services program, followed by the Commercial Crew Development program. On 23 December 2008, NASA announced the initial awarding of cargo contracts - twelve flights to SpaceX and eight flights to Orbital Sciences Corporation . PlanetSpace , which was not selected, submitted a protest to the Government Accountability Office . On 22 April 2009,
4998-526: The Dream Chaser spaceplane itself. Boeing's proposal likewise used a cargo version of its CST-100 crew vehicle. Lockheed Martin proposed a new cargo spacecraft called Jupiter , derived from the designs of the NASA's MAVEN and Juno spacecraft. It would have included a robotic arm based on Canadarm technology and a 4.4-meter (14 ft) diameter cargo transport module called Exoliner based on
SECTION 50
#17327905936255096-450: The GAO publicly released its decision to deny the protest, allowing the program to continue. The Antares and Falcon 9 launch vehicles and Cygnus and Dragon cargo spacecraft were developed using Space Act Agreements under NASA's Commercial Orbital Transportation Services (COTS) program. The first flight contracted by NASA, COTS Demo Flight 1 , took place on 8 December 2010, demonstrating
5194-793: The Gram-negative cell wall, and only members of the Bacillota group and actinomycetota (previously known as the low G+C and high G+C Gram-positive bacteria, respectively) have the alternative Gram-positive arrangement. These differences in structure can produce differences in antibiotic susceptibility; for instance, vancomycin can kill only Gram-positive bacteria and is ineffective against Gram-negative pathogens , such as Haemophilus influenzae or Pseudomonas aeruginosa . Some bacteria have cell wall structures that are neither classically Gram-positive or Gram-negative. This includes clinically important bacteria such as mycobacteria which have
5292-539: The ISS on 12 January 2021 at 14:05 UTC. SpaceX recovery teams were on standby for the parachute-assisted splashdown on 14 January 2021 at 01:26 UTC in the Gulf of Mexico , west of Tampa, Florida . Dragon returned to Earth with 2,002 kg (4,414 lb) of cargo, according to NASA . NASA contracted for the CRS-21 mission from SpaceX and therefore determines the primary payload, date of launch, and orbital parameters for
5390-668: The ISS. The spacecraft reentered on 31 May, landed in the Pacific Ocean, and was recovered, completed CRS certification requirements. Orbital Sciences first launched the Antares rocket from the Mid-Atlantic Regional Spaceport on 21 April 2013 with a test payload. Orbital Sciences completed the Cygnus Orb-D1 demonstration flight on 29 September 2013, and the operational Cygnus CRS Orb-1
5488-579: The Rodent Research-23 mission, along with used habitats and transporters that support future research missions and analysis. Minus Eighty Laboratory Freezer for ISS (MELFI) Electronics Unit : Failed cold stowage item requiring ground repair to enable future cold stowage missions. Thermal Amine Bulk Water Save Valve : Failed valve that supports efficient usage of the Thermal Amine system returning to ground for repair. The returned valve
5586-425: The archaeal/eukaryotic lineage. The most recent common ancestor (MRCA) of bacteria and archaea was probably a hyperthermophile that lived about 2.5 billion–3.2 billion years ago. The earliest life on land may have been bacteria some 3.22 billion years ago. Bacteria were also involved in the second great evolutionary divergence, that of the archaea and eukaryotes. Here, eukaryotes resulted from
5684-455: The atmosphere and one cubic metre of air holds around one hundred million bacterial cells. The oceans and seas harbour around 3 x 10 bacteria which provide up to 50% of the oxygen humans breathe. Only around 2% of bacterial species have been fully studied. Size . Bacteria display a wide diversity of shapes and sizes. Bacterial cells are about one-tenth the size of eukaryotic cells and are typically 0.5–5.0 micrometres in length. However,
5782-520: The bacteria have come into contact with in the past, which allows them to block virus replication through a form of RNA interference . Third, bacteria can transfer genetic material through direct cell contact via conjugation . In ordinary circumstances, transduction, conjugation, and transformation involve transfer of DNA between individual bacteria of the same species, but occasionally transfer may occur between individuals of different bacterial species, and this may have significant consequences, such as
5880-444: The bacteria perform separate tasks; for example, about one in ten cells migrate to the top of a fruiting body and differentiate into a specialised dormant state called a myxospore, which is more resistant to drying and other adverse environmental conditions. Biofilms . Bacteria often attach to surfaces and form dense aggregations called biofilms and larger formations known as microbial mats . These biofilms and mats can range from
5978-401: The bacteria run out of nutrients and die. Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacteria Carsonella ruddii , to 12,200,000 base pairs (12.2 Mbp) in the soil-dwelling bacteria Sorangium cellulosum . There are many exceptions to this; for example, some Streptomyces and Borrelia species contain
SECTION 60
#17327905936256076-412: The bacterial chromosome, introducing foreign DNA in a process known as transduction . Many types of bacteriophage exist; some infect and lyse their host bacteria, while others insert into the bacterial chromosome. Bacteria resist phage infection through restriction modification systems that degrade foreign DNA and a system that uses CRISPR sequences to retain fragments of the genomes of phage that
6174-502: The breakdown of oil spills , the production of cheese and yogurt through fermentation , the recovery of gold, palladium , copper and other metals in the mining sector ( biomining , bioleaching ), as well as in biotechnology , and the manufacture of antibiotics and other chemicals. Once regarded as plants constituting the class Schizomycetes ("fission fungi"), bacteria are now classified as prokaryotes . Unlike cells of animals and other eukaryotes , bacterial cells do not contain
6272-437: The cell forward. Motile bacteria are attracted or repelled by certain stimuli in behaviours called taxes : these include chemotaxis , phototaxis , energy taxis , and magnetotaxis . In one peculiar group, the myxobacteria, individual bacteria move together to form waves of cells that then differentiate to form fruiting bodies containing spores. The myxobacteria move only when on solid surfaces, unlike E. coli , which
6370-629: The cytoplasm of the cell; generally, a single endospore develops in each cell. Each endospore contains a core of DNA and ribosomes surrounded by a cortex layer and protected by a multilayer rigid coat composed of peptidoglycan and a variety of proteins. Endospores show no detectable metabolism and can survive extreme physical and chemical stresses, such as high levels of UV light , gamma radiation , detergents , disinfectants , heat, freezing, pressure, and desiccation . In this dormant state, these organisms may remain viable for millions of years. Endospores even allow bacteria to survive exposure to
6468-419: The cytoplasm which compartmentalise aspects of bacterial metabolism, such as the carboxysome . Additionally, bacteria have a multi-component cytoskeleton to control the localisation of proteins and nucleic acids within the cell, and to manage the process of cell division . Many important biochemical reactions, such as energy generation, occur due to concentration gradients across membranes, creating
6566-537: The damage they can cause, as well as the process to repair the tissue, called brazing, and if it still works in a zero-gravity environment. Three-Dimensional Microbial Monitoring (3DMM) is a project that aims to construct a three-dimensional map of bacteria and metabolites that are present at various locations throughout the ISS, and determine how the spaceflight environment affects the various species identified. Monoclonal Crystal Research in Microgravity (MCRM)
6664-411: The dominant forms of life. Although bacterial fossils exist, such as stromatolites , their lack of distinctive morphology prevents them from being used to examine the history of bacterial evolution, or to date the time of origin of a particular bacterial species. However, gene sequences can be used to reconstruct the bacterial phylogeny , and these studies indicate that bacteria diverged first from
6762-526: The elongated filaments of Actinomycetota species, the aggregates of Myxobacteria species, and the complex hyphae of Streptomyces species. These multicellular structures are often only seen in certain conditions. For example, when starved of amino acids, myxobacteria detect surrounding cells in a process known as quorum sensing , migrate towards each other, and aggregate to form fruiting bodies up to 500 micrometres long and containing approximately 100,000 bacterial cells. In these fruiting bodies,
6860-501: The energy released by the transfer of ions down an electrochemical gradient across the cell membrane. Fimbriae (sometimes called " attachment pili ") are fine filaments of protein, usually 2–10 nanometres in diameter and up to several micrometres in length. They are distributed over the surface of the cell, and resemble fine hairs when seen under the electron microscope . Fimbriae are believed to be involved in attachment to solid surfaces or to other cells, and are essential for
6958-602: The entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea. This involved the engulfment by proto-eukaryotic cells of alphaproteobacterial symbionts to form either mitochondria or hydrogenosomes , which are still found in all known Eukarya (sometimes in highly reduced form , e.g. in ancient "amitochondrial" protozoa). Later, some eukaryotes that already contained mitochondria also engulfed cyanobacteria -like organisms, leading to
7056-641: The evolution of different growth strategies (see r/K selection theory ). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal and cyanobacterial blooms that often occur in lakes during the summer. Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomyces that inhibit the growth of competing microorganisms. In nature, many organisms live in communities (e.g., biofilms ) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential for growth of
7154-465: The first Cargo Dragon flight that was docked at the same time as a Crew Dragon spacecraft ( SpaceX Crew-1 ). This mission used Booster B1058.4, becoming the first NASA mission to reuse a booster previously used on a non-NASA mission. This was also first time SpaceX launched a NASA payload on a booster with more than one previous flight. SpaceX plans to reuse the Cargo Dragons up to five times. It
7252-570: The formation of chloroplasts in algae and plants. This is known as primary endosymbiosis . Bacteria are ubiquitous, living in every possible habitat on the planet including soil, underwater, deep in Earth's crust and even such extreme environments as acidic hot springs and radioactive waste. There are thought to be approximately 2×10 bacteria on Earth, forming a biomass that is only exceeded by plants. They are abundant in lakes and oceans, in arctic ice, and geothermal springs where they provide
7350-453: The gut. However, several species of bacteria are pathogenic and cause infectious diseases , including cholera , syphilis , anthrax , leprosy , tuberculosis , tetanus and bubonic plague . The most common fatal bacterial diseases are respiratory infections . Antibiotics are used to treat bacterial infections and are also used in farming, making antibiotic resistance a growing problem. Bacteria are important in sewage treatment and
7448-486: The introduction of a larger Enhanced Cygnus, enabled Orbital ATK to cover their initial CRS contracted payload obligation by OA-7. During August 2015, Orbital ATK disclosed that they had received an extension of the resupply program for four extra missions. These flights enable NASA to cover ISS resupply needs until CRS-2 begins. NASA began a formal process to initiate Phase 2 of the Commercial Resupply Services, or CRS-2, in early 2014. Later that year, an "Industry Day"
7546-409: The laboratory. The study of bacteria is known as bacteriology , a branch of microbiology . Like all animals, humans carry vast numbers (approximately 10 to 10 ) of bacteria. Most are in the gut , though there are many on the skin. Most of the bacteria in and on the body are harmless or rendered so by the protective effects of the immune system , and many are beneficial , particularly the ones in
7644-627: The largest viruses . Some bacteria may be even smaller, but these ultramicrobacteria are not well-studied. Shape . Most bacterial species are either spherical, called cocci ( singular coccus , from Greek kókkos , grain, seed), or rod-shaped, called bacilli ( sing . bacillus, from Latin baculus , stick). Some bacteria, called vibrio , are shaped like slightly curved rods or comma-shaped; others can be spiral-shaped, called spirilla , or tightly coiled, called spirochaetes . A small number of other unusual shapes have been described, such as star-shaped bacteria. This wide variety of shapes
7742-716: The light probably serves to attract fish or other large animals. Bacteria often function as multicellular aggregates known as biofilms , exchanging a variety of molecular signals for intercell communication and engaging in coordinated multicellular behaviour. The communal benefits of multicellular cooperation include a cellular division of labour , accessing resources that cannot effectively be used by single cells, collectively defending against antagonists, and optimising population survival by differentiating into distinct cell types. For example, bacteria in biofilms can have more than five hundred times increased resistance to antibacterial agents than individual "planktonic" bacteria of
7840-499: The new Antares 300 series (Antares 330) rockets with booster stage and engines developed by Firefly Aerospace . These missions are also slated to use a new enlarged "Mission B" variant of the Cygnus spacecraft. Bacteria See § Phyla Bacteria ( / b æ k ˈ t ɪər i ə / ; sg. : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell . They constitute
7938-417: The newly formed daughter cells. Examples include fruiting body formation by myxobacteria and aerial hyphae formation by Streptomyces species, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell. In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media , such as agar plates , are used to isolate pure cultures of
8036-473: The nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane , to energy. They live on and in plants and animals. Most do not cause diseases, are beneficial to their environments, and are essential for life. The soil is a rich source of bacteria and a few grams contain around a thousand million of them. They are all essential to soil ecology, breaking down toxic waste and recycling nutrients. They are even found in
8134-475: The outside of the cell membrane is the cell wall . Bacterial cell walls are made of peptidoglycan (also called murein), which is made from polysaccharide chains cross-linked by peptides containing D- amino acids . Bacterial cell walls are different from the cell walls of plants and fungi , which are made of cellulose and chitin , respectively. The cell wall of bacteria is also distinct from that of achaea, which do not contain peptidoglycan. The cell wall
8232-612: The production of the highly toxic forms of mercury ( methyl- and dimethylmercury ) in the environment. Nonrespiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves. Unlike in multicellular organisms, increases in cell size ( cell growth ) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to
8330-560: The replication of DNA or from exposure to mutagens . Mutation rates vary widely among different species of bacteria and even among different clones of a single species of bacteria. Genetic changes in bacterial genomes emerge from either random mutation during replication or "stress-directed mutation", where genes involved in a particular growth-limiting process have an increased mutation rate. Some bacteria transfer genetic material between cells. This can occur in three main ways. First, bacteria can take up exogenous DNA from their environment in
8428-530: The same species. One type of intercellular communication by a molecular signal is called quorum sensing , which serves the purpose of determining whether the local population density is sufficient to support investment in processes that are only successful if large numbers of similar organisms behave similarly, such as excreting digestive enzymes or emitting light. Quorum sensing enables bacteria to coordinate gene expression and to produce, release, and detect autoinducers or pheromones that accumulate with
8526-476: The space station for up to 75 days, more than twice as long as the first-generation Dragon spacecraft". With this mission, this was the first time that two Dragon capsules were docked at the ISS at the same time. Beginning with the CRS-21 mission, the new Dragon Cargo capsules splash down under parachutes off the coast of Florida in either the Atlantic Ocean or the Gulf of Mexico . This NASA preference
8624-412: The surfaces of plants, the majority of bacteria are bound to surfaces in biofilms. Biofilms are also important in medicine, as these structures are often present during chronic bacterial infections or in infections of implanted medical devices , and bacteria protected within biofilms are much harder to kill than individual isolated bacteria. The bacterial cell is surrounded by a cell membrane , which
8722-457: The terminal electron acceptor, while anaerobic organisms use other compounds such as nitrate , sulfate , or carbon dioxide. Many bacteria, called heterotrophs , derive their carbon from other organic carbon . Others, such as cyanobacteria and some purple bacteria , are autotrophic , meaning they obtain cellular carbon by fixing carbon dioxide . In unusual circumstances, the gas methane can be used by methanotrophic bacteria as both
8820-447: The transfer of antibiotic resistance. In such cases, gene acquisition from other bacteria or the environment is called horizontal gene transfer and may be common under natural conditions. Many bacteria are motile (able to move themselves) and do so using a variety of mechanisms. The best studied of these are flagella , long filaments that are turned by a motor at the base to generate propeller-like movement. The bacterial flagellum
8918-524: The treadmill, a critical item returning to the ground following the on-orbit replacement with a working spare. Carbon Dioxide Removal Assembly (CDRA) Air Selector Valve : Critical degraded valve returning for repair and refurbishment to support the carbon dioxide removal capability on-orbit. Nitrogen Oxygen Recharge System (NORS) Tank : Depressurized tank capable of flying oxygen or nitrogen, and will be utilized for future on-orbit demand in 2021. Rodent Research Habitats and Transporters : Live rodents from
9016-445: The treatment of numerous diseases, including cancer. Rodent Research-23 will study the effects of spaceflight on the eyes, specifically on the structure and function of the arteries, veins, and lymphatic vessels that are needed to maintain vision. Student Spaceflight Experiments Program : The Student Spaceflight Experiments Program (SSEP) has 27 experiments manifested as part of Mission 14A. The CRS-21 pressurized capsule carries
9114-495: The virulence of some bacterial pathogens. Pili ( sing . pilus) are cellular appendages, slightly larger than fimbriae, that can transfer genetic material between bacterial cells in a process called conjugation where they are called conjugation pili or sex pili (see bacterial genetics, below). They can also generate movement where they are called type IV pili . Glycocalyx is produced by many bacteria to surround their cells, and varies in structural complexity: ranging from
9212-433: Was added to CRS-2 awards. T+00:00: Liftoff T+01:18: Maximum aerodynamic pressure T+02:30: First stage main engine cutoff (MECO) T+02:34: Stage separation T+02:41: Second stage engine start T+06:37: First stage entry burn begins T+08:38: Second stage engine cutoff (SECO) T+08:38: First stage landing on drone ship T+11:49: Dragon separation T+12:35: Dragon nose cone open sequence begins Dragon undocked from
9310-617: Was held in Houston, with seven high-level requirements disclosed to interested parties. The contracts were expected to include a variety of requirements: CRS-1 contractors Orbital Sciences and SpaceX each submitted CRS-2 proposals, joined by Sierra Nevada , Boeing , and Lockheed Martin . SNC's proposal would use a cargo version of its Dream Chaser crew vehicle, the 'Dream Chaser Cargo System'. The proposed cargo Dream Chaser included an additional expendable cargo module for uplift and trash disposal. Downmass would only be provided via
9408-454: Was launched 9 January 2014. Transport flights began under Commercial Resupply Services phase 1 (CRS-1) in 2012: Following the failure, the Antares 230 system was upgraded with newly built RD-181 first-stage engines to provide greater payload performance and increased reliability. The next two spacecraft were launched on the Atlas V . With the switch to more powerful launch vehicles and
9506-603: Was launched without seats, cockpit controls, the life support system required to sustain astronauts in space and SuperDraco abort engines. Dragon 2 improves on Dragon 1 in several ways, including lessened refurbishment time, leading to shorter periods between flights. While CRS-21 was for a standard 30 days mission, the most recent Flight Planning Integration Panel (FPIP) document indicates that beginning with CRS-23, SpaceX cargo missions will begin to stretch out to 60 days and beyond. Sarah Walker, director of Dragon mission management at SpaceX, said "the new Cargo Dragon can stay at
9604-530: Was solicited in 2014. CRS-2 contracts were awarded in January 2016 to Orbital ATK’s continued use of Cygnus , Sierra Nevada Corporation ’s new Dream Chaser , and SpaceX’s new Dragon 2 , for cargo transport flights beginning in 2019 and expected to last through 2024. NASA has been directed to pursue commercial spaceflight options since at least 1984, with the Commercial Space Launch Act of 1984 and Launch Services Purchase Act of 1990. By
#624375