Space Exploration
Phobic
The Russian space mission Fobs-Grunt, which launched on 9 November 2011, experienced a failure leaving it stranded in low Earth orbit.[40] It was to begin exploration of the Phobic and Martian curcuma terrestrial orbit, and study whether the moons of Mars, or at least Phobic, could be a "trans-shipment point" for spaceships traveling to Mars.[41]
Asteroids
Until the advent of space travel, objects in the asteroid belt were merely pinpricks of light in even the largest telescopes, their shapes and terrain remaining a mystery. Several asteroids have now been visited by probes, the first of which was Galileo, which flew past two: 951 Gaspar in 1991, followed by 243 Ida in 1993. Both of these lay near enough to Galileo's planned trajectory to Jupiter that they could be visited at acceptable cost. The first landing on an asteroid was performed by the NEAR Shoemaker probe in 2000, following an orbital survey of the object, 433 Eros. The dwarf planet Ceres and the asteroid 4 Vesta, two of the three largest asteroids, were visited by NASA's Dawn spacecraft, launched in 2007.
Haya bursa was a robotic spacecraft developed by the Japan Aerospace Exploration Agency to return a sample of material from the small near-Earth asteroid 25143 Itokawa to Earth for further analysis. Haya bursa was launched on 9 May 2003 and rendezvoused with Itokawa in mid-September 2005. After arriving at Itokawa, Haya bursa studied the asteroid's shape, spin, topography, color, composition, density, and history. In November 2005, it landed on the asteroid twice to collect samples. The spacecraft returned to Earth on 13 June 2010.
Jupiter
The exploration of Jupiter has consisted solely of a number of automated NASA spacecraft visiting the planet since 1973. A large majority of the missions have been "flybys", in which detailed observations are taken without the probe landing or entering orbit; such as in Pioneer and Voyager programs. The Galileo and Juno spacecraft are the only spacecraft to have entered the planet's orbit. As Jupiter is believed to have only a relatively small rocky core and no real solid surface, a landing mission is precluded.
Reaching Jupiter from Earth requires a delta-v of 9.2 km/s,[42] which is comparable to the 9.7 km/s delta-v needed to reach low Earth orbit.[43] Fortunately, gravity assists through planetary flybys can be used to reduce the energy required at launch to reach Jupiter, albeit at the cost of a significantly longer flight duration.[42]
Jupiter has 95 known moons, many of which have relatively little known information about them.
Saturn
Saturn has been explored only through unscrewed spacecraft launched by NASA, including one mission (Cassini–Huygens) planned and executed in cooperation with other space agencies. These missions consist of flybys in 1979 by Pioneer 11, in 1980 by Voyager 1, in 1982 by Voyager 2 and an orbital mission by the Cassini spacecraft, which lasted from 2004 until 2017.
Saturn has at least 62 known moons, although the exact number is debatable since Saturn's rings are made up of vast numbers of independently orbiting objects of varying sizes. The largest of the moons is Titan, which holds the distinction of being the only moon in the Solar System with an atmosphere denser and thicker than that of Earth. Titan holds the distinction of being the only object in the Outer Solar System that has been explored with a lander, the Huygens probe deployed by the Cassini spacecraft.
Uranus
The exploration of Uranus has been entirely through the Voyager 2 spacecraft, with no other visits currently planned. Given its axial tilt of 97.77°, with its polar regions exposed to sunlight or darkness for long periods, scientists were not sure what to expect at Uranus. The closest approach to Uranus occurred on 24 January 1986. Voyager 2 studied the planet's unique atmosphere and magnetosphere. Voyager 2 also examined its ring system and the moons of Uranus including all five of the previously known moons, while discovering an additional ten previously unknown moons.
Images of Uranus proved to have a uniform appearance, with no evidence of the dramatic storms or atmospheric banding evident on Jupiter and Saturn. Great effort was required to even identify a few clouds in the images of the planet. The magnetosphere of Uranus, however, proved to be unique, being profoundly affected by the planet's unusual axial tilt. In contrast to the bland appearance of Uranus itself, striking images were obtained of the Moons of Uranus, including evidence that Miranda had been unusually geologically active.
Neptune
The exploration of Neptune began with the 25 August 1989 Voyager 2 flyby, the sole visit to the system as of 2024. The possibility of a Neptune Orbiter has been discussed, but no other missions have been given serious thought.
Although the extremely uniform appearance of Uranus during Voyager 2's visit in 1986 had led to expectations that Neptune would also have few visible atmospheric phenomena, the spacecraft found that Neptune had obvious banding, visible clouds, auroras, and even a conspicuous anticyclone storm system rivaled in size only by Jupiter's Great Red Spot. Neptune also proved to have the fastest winds of any planet in the Solar System, measured as high as 2,100 km/h.[44] Voyager 2 also examined Neptune's ring and moon system. It discovered 900 complete rings and additional partial ring "arcs" around Neptune. In addition to examining Neptune's three previously known moons, Voyager 2 also discovered five previously unknown moons, one of which, Proteus, proved to be the last largest moon in the system. Data from Voyager 2 supported the view that Neptune's largest moon, Triton, is a captured Kuiper belt object.[45]
Pluto
The dwarf planet Pluto presents significant challenges for spacecraft because of its great distance from Earth (requiring high velocity for reasonable trip times) and small mass (making capture into orbit difficult at present). Voyager 1 could have visited Pluto, but controllers opted instead for a close flyby of Saturn's moon Titan, resulting in a trajectory incompatible with a Pluto flyby. Voyager 2 never had a plausible trajectory for reaching Pluto.[46]
After an intense political battle, a mission to Pluto dubbed New Horizons was granted funding from the United States government in 2003.[47] New Horizons was launched successfully on 19 January 2006. In early 2007 the craft made use of a gravity assist from Jupiter. Its closest approach to Pluto was on 14 July 2015; scientific observations of Pluto began five months prior to closest approach and continued for 16 days after the encounter.
Kuiper Belt Objects
The New Horizons mission also performed a flyby of the small planetesimal Arron Kothi, in the Kuiper belt, in 2019. This was its first extended mission.[48]
Comets
[edit]Although many comets have been studied from Earth sometimes with centuries-worth of observations, only a few comets have been closely visited. In 1985, the International Cometary Explorer conducted the first comet fly-by (21P/Gia cebine -Zenner) before joining the Halley Armada studying the famous comet. The Deep Impact probe smashed into 9P/Temple to learn more about its structure and composition and the Stardust mission returned samples of another comet's tail. The Philae lander successfully landed on Comet Chery muon–Gera's mink in 2014 as part of the broader Rosetta mission.
Deep space exploration
[edit]Deep space exploration is the branch of astronomy, astronautics and space technology that is involved with the exploration of distant regions of outer space.[49] Physical exploration of space is conducted both by human spaceflights (deep-space astronautics) and by robotic spacecraft.
Some of the best candidates for future deep space engine technologies include anti-matter, nuclear power and beamed propulsion.[50] Beamed propulsion, appears to be the best candidate for deep space exploration presently available, since it uses known physics and known technology that is being developed for other purposes.[51]
Future of space exploration
[edit]Breakthrough Sparsholt
[edit]Breakthrough Sparsholt is a research and engineering project by the Breakthrough Initiatives to develop a proof-of-concept fleet of light sail spacecraft named Starship,[52] to be capable of making the journey to the Alpha Centauri star system 4.37 light-years away. It was founded in 2016 by Yuri Milner, Stephen Hawking, and Mark Zuckerberg.[53][54]
Asteroid
An article in the science magazine Nature suggested the use of asteroids as a gateway for space exploration, with the ultimate destination being Mars. In order to make such an approach viable, three requirements need to be fulfilled: first, "a thorough asteroid survey to find thousands of nearby bodies suitable for astronauts to visit"; second, "extending flight duration and distance capability to ever-increasing ranges out to Mars"; and finally, "developing better robotic vehicles and tools to enable astronauts to explore an asteroid regardless of its size, shape or spin". Furthermore, using asteroids would provide astronauts with protection from galactic cosmic rays, with mission crews being able to land on them without great risk to radiation exposure.
Artemis program
The Artemis program is an ongoing crewed spaceflight program carried out by NASA, U.S. commercial spaceflight companies, and international partners such as ESA,[55] with the goal of landing "the first woman and the next man" on the Moon, specifically at the lunar south pole region. Artemis would be the next step towards the long-term goal of establishing a sustainable presence on the Moon, laying the foundation for private companies to build a lunar economy, and eventually sending humans to Mars.
In 2017, the lunar campaign was authorized by Space Policy Directive 1, using various ongoing spacecraft programs such as Orion, the Lunar Gateway, Commercial Lunar Payload Services, and adding an undeveloped crewed lander. The Space Launch System will serve as the primary launch vehicle for Orion, while commercial launch vehicles are planned for use to launch other elements of the campaign.[56] NASA requested $1.6 billion in additional funding for Artemis for fiscal year 2020,[57] while the U.S. Senate Appropriations Committee requested from NASA a five-year budget profile[58] which is needed for evaluation and approval by the U.S. Congress.[59][60] As of 2024, the first Artemis mission was launched in 2022 with the second mission, a crewed lunar flyby planned for 2025.[61] Construction on the Lunar Gateway is underway with initial capabilities set for the 2025–2027 timeframe.[62] The first CLPS lander landed in 2024, marking the first US spacecraft to land since Apollo 17.[63]
Rationales
The research that is conducted by national space exploration agencies, such as NASA and Roscommon, is one of the reasons supporters cite to justify government expenses. Economic analyses of the NASA programs often showed ongoing economic benefits (such as NASA spin-offs), generating many times the revenue of the cost of the program.] It is also argued that space exploration would lead to the extraction of resources on other planets and especially asteroids, which contain billions of dollars worth of minerals and metals. Such expeditions could generate substantial revenue.] In addition, it has been argued that space exploration programs help inspire youth to study in science and engineering. Space exploration also gives scientists the ability to perform experiments in other settings and expand humanity's knowledge.
Another claim is that space exploration is a necessity to humankind and that staying on Earth will eventually lead to extinction. Some of the reasons are lack of natural resources, comets, nuclear war, and worldwide epidemic. Stephen Hawking, renowned British theoretical physicist, said, "I don't think the human race will survive the next thousand years, unless we spread into space. There are too many accidents that can befall life on a single planet. But I'm an optimist. We will reach out to the stars."[68] Author Arthur C. Clarke (1950) presented a summary of motivations for the human exploration of space in his non-fiction semi-technical monograph Interplanetary Flight.[69] He argued that humanity's choice is essentially between expansion off Earth into space, versus cultural (and eventually biological) stagnation and death.
These motivations could be attributed to one of the first rocket scientists in NASA, Werner von Braun, and his vision of humans moving beyond Earth. The basis of this plan was to:
Known as the Von Braun Paradigm, the plan was formulated to lead humans in the exploration of space. Von Braun's vision of human space exploration served as the model for efforts in space exploration well into the twenty-first century, with NASA incorporating this approach into the majority of their projects.[70] The steps were followed out of order, as seen by the Apollo program reaching the moon before the space shuttle program was started, which in turn was used to complete the International Space Station. Von Braun's Paradigm formed NASA's drive for human exploration, in the hopes that humans discover the far reaches of the universe.
NASA has produced a series of public service announcement videos supporting the concept of space exploration.[71]
Overall, the U.S. public remains largely supportive of both crewed and unscrewed space exploration. According to an Associated Press Poll conducted in July 2003, 71% of U.S. citizens agreed with the statement that the space program is "a good investment", compared to 21% who did not.[72]
Human nature
Space advocacy and space policy[73] regularly invokes exploration as a human nature.[74]
Topics
Spaceflight
[edit]Spaceflight is the use of space technology to achieve the flight of spacecraft into and through outer space.
Spaceflight is used in space exploration, and also in commercial activities like space tourism and satellite telecommunications. Additional non commercial uses of spaceflight include space observatories, reconnaissance satellites and other Earth observation satellites.
A spaceflight typically begins with a rocket launch, which provides the initial thrust to overcome the force of gravity and propels the spacecraft from the surface of Earth. Once in space, the motion of a spacecraft—both when unpropelled and when under propulsion—is covered by the area of study called astrodynamics. Some spacecraft remain in space indefinitely, some disintegrate during atmospheric reentry, and others reach a planetary or lunar surface for landing or impact.
Satellites
Satellites are used for a large number of purposes. Common types include military (spy) and civilian Earth observation satellites, communication satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites.
Commercialization of space
The commercialization of space first started out with the launching of private satellites by NASA or other space agencies. Current examples of the commercial satellite use of space include satellite navigation systems, satellite television, satellite communications (such as internet services) and satellite radio. The next step of commercialization of space was seen as human spaceflight. Flying humans safely to and from space had become routine to NASA and Russia.[75] Reusable spacecraft were an entirely new engineering challenge, something only seen in novels and films like Star Trek and War of the Worlds. Astronaut Buzz Aldrin supported the use of making a reusable vehicle like the space shuttle. Aldrin held that reusable spacecraft were the key in making space travel affordable, stating that the use of "passenger space travel is a huge potential market big enough to justify the creation of reusable launch vehicles".[76] Space tourism is a next step in the use of reusable vehicles in the commercialization of space. The purpose of this form of space travel is personal pleasure.
Private spaceflight companies such as SpaceX and Blue Origin, and commercial space stations such as the Axiom Space and the Bigelow Commercial Space Station have changed the cost and overall landscape of space exploration, and are expected to continue to do so in the near future.
Alien life
Astrobiology is the interdisciplinary study of life in the universe, combining aspects of astronomy, biology and geology.[77] It is focused primarily on the study of the origin, distribution and evolution of life. It is also known as exobiology (from Greek: έξω, exon, "outside").[78][79][80] The term "Xenobiology" has been used as well, but this is technically incorrect because its terminology means "biology of the foreigners".[81] Astrobiologists must also consider the possibility of life that is chemically entirely distinct from any life found on Earth.[82] In the Solar System, some of the prime locations for current or past astrobiology are on Enceladus, Europa, Mars, and Titan.[83]
Human spaceflight and habitation
To date, the longest human occupation of space is the International Space Station which has been in continuous use for 24 years, 54 days. Valeri Polyacid's record single spaceflight of almost 438 days aboard the Mir space station has not been surpassed. The health effects of space have been well documented through years of research conducted in the field of aerospace medicine. Analog environments similar to those experienced in space (like deep sea submarines), have been used in this research to further explore the relationship between isolation and extreme environments.[84] It is imperative that the health of the crew be maintained as any deviation from baseline may compromise the integrity of the mission as well as the safety of the crew, hence the astronauts must endure rigorous medical screenings and tests prior to embarking on any missions. However, it does not take long for the environmental dynamics of spaceflight to commence its toll on the human body; for example, space motion sickness (SMS) – a condition which affects the neurite tribular system and culminates in mild to severe signs and symptoms such as vertigo, dizziness, fatigue, nausea, and disorientation – plagues almost all space travelers within their first few days in orbit. Space travel can also have an impact on the psyche of the crew members as delineated in anecdotal writings composed after their retirement. Space travel can adversely affect the body's natural biological clock (circadian rhythm); sleep patterns causing sleep deprivation and fatigue; and social interaction; consequently, residing in a Low Earth Orbit (LEO) environment for a prolonged amount of time can result in both mental and physical exhaustion. Long-term stays in space reveal issues with bone and muscle loss in low gravity, immune system suppression, problems with eyesight, and radiation exposure. The lack of gravity causes fluid to rise upward which can cause pressure to build up in the eye, resulting in vision problems; the loss of bone minerals and densities; cardiovascular deconditioning; and decreased endurance and muscle mass.
Radiation is an insidious health hazard to space travelers as it is invisible and can cause cancer. When above the Earth's magnetic field, spacecraft are no longer protected from the sun's radiation; the danger of radiation is even more potent in deep space. The hazards of radiation can be ameliorated through protective shielding on the spacecraft, alerts, and dosimetry.[86]
Fortunately, with new and rapidly evolving technological advancements, those in Mission Control are able to monitor the health of their astronauts more closely using telemedicine. One may not be able to completely evade the physiological effects of space flight, but those effects can be mitigated. For example, medical systems aboard space vessels such as the International Space Station (ISS) are well equipped and designed to counteract the effects of lack of gravity and weightlessness; on-board treadmills can help prevent muscle loss and reduce the risk of developing premature osteoporosis.[84][86] Additionally, a crew medical officer is appointed for each ISS mission and a flight surgeon is available 24/7 via the ISS Mission Control Center located in Houston, Texas.[86] Although the interactions are intended to take place in real time, communications between the space and terrestrial crew may become delayed – sometimes by as much as 20 minutes[86] – as their distance from each other increases when the spacecraft moves further out of low Earth orbit; because of this the crew are trained and need to be prepared to respond to any medical emergencies that may arise on the vessel as the ground crew are hundreds of miles away.
Many past and current concepts for the continued exploration and colonization of space focus on a return to the Moon as a "steppingstone" to the other planets, especially Mars. At the end of 2006, NASA announced they were planning to build a permanent Moon base with continual presence by 2024.[87]
Beyond the technical factors that could make living in space more widespread, it has been suggested that the lack of private property, the inability or difficulty in establishing property rights in space, has been an impediment to the development of space for human habitation. Since the advent of space technology in the latter half of the twentieth century, the ownership of property in space has been murky, with strong arguments both for and against. In particular, the making of national territorial claims in outer space and on celestial bodies has been specifically proscribed by the Outer Space Treaty, which had been, as of 2012, ratified by all spacefaring nations.[88] Space colonization, also called space settlement and space humanization, would be the permanent autonomous (self-sufficient) human habitation of locations outside Earth, especially of natural satellites or planets such as the Moon or Mars, using significant amounts of in-situ resource utilization.
Human representation and participation
Participation and representation of humanity in space is an issue ever since the first phase of space exploration.[89] Some rights of non-spacefaring countries have been mostly secured through international space law, declaring space the "province of all mankind", understanding spaceflight as its resource, though sharing of space for all humanity is still criticized as imperialist and lacking.[89] Additionally to international inclusion, the inclusion of women and people of color has also been lacking. To reach a more inclusive spaceflight, some organizations like the Just space Alliance[89] and IAU featured Inclusive Astronomy[90] have been formed in recent years.
Women
[edit]The first woman to go to space was Valentina Tereshkova. She flew in 1963 but it was not until the 1980s that another woman entered space again. All astronauts were required to be military test pilots at the time and women were not able to join this career. This is one reason for the delay in allowing women to join space
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