Saya mengajak kepada seluruh lapisan masyarakat, khususnya para tokoh dan cendekiawan di kampus‐kampus serta di lembaga‐lembaga kajian dan penelitian lain untuk secara serius merumuskan implementasi peran iptek dalam berbagai aspek kehidupan bangsa dalam konteks masa kini dan masa depan.
~Prof. Dr. Ing. Bacharuddin Jusuf Habibie~
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon.
The world's first artificial satellite, the Sputnik 1, was launched by the Soviet Union in 1957. Since then, thousands of satellites have been launched into orbit around the Earth. Some satellites, notably space stations, have been launched in parts and assembled in orbit. Artificial satellites originate from more than 50 countries and have used the satellite launching capabilities of ten nations.
A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A fewspace probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars,Jupiter, Saturn, and the Sun.
A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A fewspace probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars,Jupiter, Saturn, and the Sun.
Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites,communications satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.
Satellites are usually semi-independent computer-controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control and orbit control.
Eksplorasi antariksa negara-negara maju sudah mencapai Planet Mars dan sedang menjajaki untuk mengeksplorasi asteroid dalam waktu beberapa tahun ke depan. Tak mau ketinggalan terlalu jauh, Indonesia rupanya kini mulai ikut mengembangkan teknologi untuk mengeksplorasi antariksa.
Langkah awalnya adalah dengan meluncurkan satelit secara mandiri. Target ini diharapkan bisa dicapai dalam kurun waktu belasan tahun mendatang.
"Tahun 2025, kita sudah akan bisa meluncurkan satelit sendiri. Setelah itu kita menuju program ke Bulan," kata Kepala Lembaga Penerbangan dan Antariksa Nasional (LAPAN), Dr. Bambang S. Tedja.
Dia menerangkan program eksplorasi bulan akan menjadi patokan untuk eksplorasi tingkat lanjut. Ia yakin pada 2025, seiring dengan terwujudnya bandara antariksa nasional, Indonesia dapat meluncurkan satelit yang bakal mengorbit di ketinggian 650 kilometer.
"Kita bisa lah pada waktunya nanti. Apalagi tahun depan kami akan meluncurkan roket untuk ujicoba," ujar Dr. Bambang.
Keyakinan tersebut didasarkan pada kesiapan LAPAN meluncurkan roket Sonda RX-550 tahun depan. Itu merupakan roket pendorong peluncuran satelit berukuran 6 meter, berdiameter 550 milimeter, dan berat 3 ton.
"Roket itu mampu mencapai ketinggian lebih dari 100 km, dan jangkauannya mencapai 300 km," katanya.
LAPAN telah melakukan uji statis roket RX-550 pada 2011 dan 2012. Uji statis merupakan pengujian di darat untuk mengetahui kinerja dan daya dorong roket saat tinggal landas. Pada 2013 dan 2014 RX-550 akan menjalani uji terbang masing-masing satu tingkat dan dua tingkat.
Meski optimistis pada 2025 nanti Indonesia akan mampu meluncurkan satelit secara mandiri, Bambang mengakui Indonesia harus mengatasi tantangan soal penempatan slot satelit di antariksa.
"Slot itu harus diiisi. Ini saja masih menjadi tantangan," katanya.
Jenis-jenis Satelit
- Anti-Satellite weapons/"Killer Satellites" are satellites that are designed to destroy enemy warheads, satellites, and other space assets.
- Astronomical satellites are satellites used for observation of distant planets, galaxies, and other outer space objects.
- Biosatellites are satellites designed to carry living organisms, generally for scientific experimentation.
- Communications satellites are satellites stationed in space for the purpose of telecommunications. Modern communications satellites typically use geosynchronous orbits, Molniya orbits or Low Earth orbits.
- Miniaturized satellites are satellites of unusually low masses and small sizes. New classifications are used to categorize these satellites: minisatellite (500–100 kg), microsatellite (below 100 kg), nanosatellite (below 10 kg).
- Navigational satellites are satellites which use radio time signals transmitted to enable mobile receivers on the ground to determine their exact location. The relatively clear line of sight between the satellites and receivers on the ground, combined with ever-improving electronics, allows satellite navigation systems to measure location to accuracies on the order of a few meters in real time.
- Reconnaissance satellites are Earth observation satellite or communications satellite deployed for military or intelligence applications. Very little is known about the full power of these satellites, as governments who operate them usually keep information pertaining to their reconnaissance satellites classified.
- Earth observation satellites are satellites intended for non-military uses such as environmental monitoring, meteorology, map making etc. (See especially Earth Observing System.)
- Tether satellites are satellites which are connected to another satellite by a thin cable called a tether.
- Weather satellites are primarily used to monitor Earth's weather and climate.
- Recovery satellites are satellites that provide a recovery of reconnaissance, biological, space-production and other payloads from orbit to Earth.
- Manned spacecraft (spaceships) are large satellites able for put human into (and beyond) an orbit, being on it and recovery back to Earth. Spacecrafts, and orbital parts-spaceplanes ofreusable systems also, has a major propulsion or landing facilities, and often uses as transport to and from the orbital stations.
- Space stations are man-made orbital structures that are designed for human beings to live on in outer space. A space station is distinguished from other manned spacecraft by its lack of major propulsion or landing facilities. Space stations are designed for medium-term living in orbit, for periods of weeks, months, or even years.
Pak. Teddy Lesmana, SE. M.M. sedang berada di belakang Pesawat Ulang-Alik Discovery
A spacecraft (or spaceship) is a vehicle, vessel or machine designed to fly in outer space.
Spacecraft are used for a variety of purposes,
including communications,
earth observation,
meteorology, navigation, planetary exploration and transportation of humans and cargo.
Spacecraft are used for a variety of purposes,
including communications,
earth observation,
meteorology, navigation, planetary exploration and transportation of humans and cargo.
On a sub-orbital spaceflight, a spacecraft enters space and then returns to the surface, without having gone into an orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, while those used for robotic space missions operate either autonomously or telerobotically.
Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificialsatellites. Only a handful of interstellar probes, such as Pioneer 10 and 11, Voyager 1 and 2, and New Horizons, are currently on trajectories that leave our Solar System.
Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificialsatellites. Only a handful of interstellar probes, such as Pioneer 10 and 11, Voyager 1 and 2, and New Horizons, are currently on trajectories that leave our Solar System.
Orbital spacecraft may be recoverable or not. By method of reentry to Earth they may be divided in non-winged space capsules and wingedspaceplanes.
Currently, only twenty-four nations have spaceflight technology: Russia (Russian Federal Space Agency), the United States (NASA, the US Air Force, SpaceX (a U.S private aerospace company)), the member states of the European Space Agency, the People's Republic of China (China National Space Administration), Japan (Japan Aerospace Exploration Agency), and India (Indian Space Research Organisation).
Spacecraft and space travel are common themes in works of science fiction.
Subsystems
A spacecraft system comprises various subsystems, dependent upon mission profile. Spacecraft subsystems comprise the spacecraft "bus" and may include: attitude determination and control (variously called ADAC, ADC or ACS), guidance, navigation and control (GNC or GN&C), communications (Comms), command and data handling (CDH or C&DH), power (EPS), thermal control(TCS), propulsion, and structures. Attached to the bus are typically payloads.
A Spacecraft needs an attitude control subsystem to be correctly oriented in space and respond to external torques and forces properly. The attitude control subsystem consists of sensors and actuators, together with controlling algorithms. The attitude control subsystem permits proper pointing for the science objective, sun pointing for power to the solar arrays and earth-pointing for communications.
- GNC
- Guidance refers to the calculation of the commands (usually done by the CDH subsystem) needed to steer the spacecraft where it is desired to be. Navigation means determining a spacecraft's orbital elements or position. Control means adjusting the path of the spacecraft to meet mission requirements. On some missions, GNC and Attitude Control are combined into one subsystem of the spacecraft.
- Command and data handling
- The CDH subsystem receives commands from the communications subsystem, performs validation and decoding of the commands, and distributes the commands to the appropriate spacecraft subsystems and components.
The CDH also receives housekeeping data and science data from the other spacecraft subsystems and components, and packages the data for storage on a data recorder or transmission to the ground via the communications subsystem. Other functions of the CDH include maintaining the spacecraft clock and state-of-health monitoring.
Further information: On-Board Data Handling
- Power
- Spacecraft need an electrical power generation and distribution subsystem for powering the various spacecraft subsystems. For spacecraft near the Sun, solar panels are frequently used to generate electrical power. Spacecraft designed to operate in more distant locations, for example Jupiter, might employ a Radioisotope Thermoelectric Generator (RTG) to generate electrical power.
Electrical power is sent through power conditioning equipment before it passes through a power distribution unit over an electrical bus to other spacecraft components. Batteries are typically connected to the bus via a battery charge regulator, and the batteries are used to provide electrical power during periods when primary power is not available, for example when a Low Earth Orbit (LEO) spacecraft is eclipsed by the Earth.
Thermal control
Spacecraft must be engineered to withstand transit through the Earth's atmosphere and the space environment. They must operate in a vacuum with temperatures potentially ranging across hundreds of degrees Celsius as well as (if subject to reentry) in the presence of plasmas. Material requirements are such that either high melting temperature, low density materials such asberyllium and reinforced carbon-carbon or (possibly due to the lower thickness requirements despite its high density) tungsten or ablative carbon/carbon composites are used.
Depending on mission profile, spacecraft may also need to operate on the surface of another planetary body. The thermal control subsystem can be passive, dependent on the selection of materials with specific radiative properties. Active thermal control makes use of electrical heaters and certain actuators such as louvers to control temperature ranges of equipments within specific ranges.
- Propulsion
- Spacecraft may or may not have a propulsion subsystem, depending upon whether or not the mission profile calls for propulsion. The Swiftspacecraft is an example of a spacecraft that does not have a propulsion subsystem. Typically though, LEO spacecraft (for example Terra (EOS AM-1) include a propulsion subsystem for altitude adjustments (called drag make-up maneuvers) and inclination adjustment maneuvers.
A propulsion system is also needed for spacecraft that perform momentum management maneuvers. Components of a conventional propulsion subsystem include fuel, tankage, valves, pipes, and thrusters. The TCS interfaces with the propulsion subsystem by monitoring the temperature of those components, and by preheating tanks and thrusters in preparation for a spacecraft maneuver.
- Structures
- Spacecraft must be engineered to withstand launch loads imparted by the launch vehicle, and must have a point of attachment for all the other subsystems. Depending upon mission profile, the structural subsystem might need to withstand loads imparted by entry into the atmosphere of another planetary body, and landing on the surface of another planetary body.
- Payload
- The payload is dependent upon the mission of the spacecraft, and is typically regarded as the part of the spacecraft "that pays the bills". Typical payloads could include scientific instruments (cameras, telescopes, or particle detectors, for example), cargo, or a human crew.
- Ground segment
- The ground segment, though not technically part of the spacecraft, is vital to the operation of the spacecraft. Typical components of a ground segment in use during normal operations include a mission operations facility where the flight operations team conducts the operations of the spacecraft, a data processing and storage facility, ground stations to radiate signals to and receive signals from the spacecraft, and a voice and data communications network to connect all mission elements.
- Launch vehicle
- The launch vehicle propels the spacecraft from the Earth's surface, through the atmosphere, and into an orbit, the exact orbit being dependent upon mission configuration. The launch vehicle may be expendable or reusable.
Tahun 2045 Indonesia Optimis Dapat Membuat dan Meluncurkan Pesawat Antariksa
Akan kami buat pesawat Antariksa untuk Indonesia, Tanah Air ku.
Ucapan Terima Kasih:
Kepada seluruh masyarakat Indonesia yang mendambakan akan kemajuan bangsa dalam penguasaan Iptek Antariksa
Kunjungi Sekolah Kami:
Indonesian University Space Research Association
1. http://asosiasiuniversitasrisetantariksa.blogspot.com/
Indonesian Space Science & Technology School
2. http://sekolahiptekkeluarangkasaan.blogspot.com/
