The Mars Orbiter Mission (MOM), also called Mangalyaan ("Mars-craft", from Sanskrit: मंगल mangala, "Mars" and यान yāna, "craft, vehicle"), is a space probe orbiting Mars since 24 September 2014. It was launched on 5 November 2013 by the Indian Space Research Organisation (ISRO). It is India's first interplanetary mission and it made it the fourth space agency to reach Mars, after Roscosmos, NASA, and the European Space Agency. It made India the first Asian nation to reach Martian orbit and the first nation in the world to do so on its maiden attempt.
The Mars Orbiter Mission probe lifted-off from the First Launch Pad at Satish Dhawan Space Centre (Sriharikota Range SHAR), Andhra Pradesh, using a Polar Satellite Launch Vehicle (PSLV) rocket C25 at 09:08 UTC on 5 November 2013. The launch window was approximately 20 days long and started on 28 October 2013. The MOM probe spent about a month in Earth orbit, where it made a series of seven apogee-raising orbital manoeuvres before trans-Mars injection on 30 November 2013 (UTC). After a 298-day transit to Mars, it was inserted into Mars orbit on 24 September 2014.
The mission is a "technology demonstrator" project to develop the technologies for designing, planning, management, and operations of an interplanetary mission. It carries five scientific instruments. The spacecraft is currently being monitored from the Spacecraft Control Centre at ISRO Telemetry, Tracking and Command Network (ISTRAC) in Bengaluru with support from the Indian Deep Space Network (IDSN) antennae at Byalalu, Karnataka.
On 23 November 2008, the first public acknowledgement of an unmanned mission to Mars was announced by then-ISRO chairman G. Madhavan Nair. The MOM mission concept began with a feasibility study in 2010 by the Indian Institute of Space Science and Technology after the launch of lunar satellite Chandrayaan-1 in 2008. Prime Minister Manmohan Singh approved the project on 3 August 2012, after the Indian Space Research Organisation completed ₹125 crore (US$18 million) of required studies for the orbiter. The total project cost may be up to ₹454 crore (US$66 million). The satellite costs ₹153 crore (US$22 million) and the rest of the budget has been attributed to ground stations and relay upgrades that will be used for other ISRO projects.
The space agency had planned the launch on 28 October 2013 but was postponed to 5 November following the delay in ISRO's spacecraft tracking ships to take up pre-determined positions due to poor weather in the Pacific Ocean. Launch opportunities for a fuel-saving Hohmann transfer orbit occur every 26 months, in this case the next two would be in 2016 and 2018.
Assembly of the PSLV-XL launch vehicle, designated C25, started on 5 August 2013. The mounting of the five scientific instruments was completed at Indian Space Research Organisation Satellite Centre, Bengaluru, and the finished spacecraft was shipped to Sriharikota on 2 October 2013 for integration to the PSLV-XL launch vehicle. The satellite's development was fast-tracked and completed in a record 15 months. Despite the US federal government shutdown, NASA reaffirmed on 5 October 2013 it would provide communications and navigation support to the mission. During a meeting on 30 September 2014, NASA and ISRO officials signed an agreement to establish a pathway for future joint missions to explore Mars. One of the working group's objectives will be to explore potential coordinated observations and science analysis between the MAVEN orbiter and MOM, as well as other current and future Mars missions.
The total cost of the mission was approximately ₹450 Crore (US$73 million), making it the least-expensive Mars mission to date. The low cost of the mission was ascribed by K. Radhakrishnan, the chairman of ISRO, to various factors, including a "modular approach", few ground tests and long (18–20 hour) working days for scientists. BBC's Jonathan Amos mentioned lower worker costs, home-grown technologies, simpler design, and a significantly less complicated payload than NASA's MAVEN.
The primary objective of the mission is to develop the technologies required for designing, planning, management and operations of an interplanetary mission. The secondary objective is to explore Mars' surface features, morphology, mineralogy and Martian atmosphere using indigenous scientific instruments.
- Orbit manoeuvres to transfer the spacecraft from Earth-centred orbit to heliocentric trajectory and finally, capture into Martian orbit
- Development of force models and algorithms for orbit and attitude (orientation) computations and analysis
- Navigation in all phases
- Maintain the spacecraft in all phases of the mission
- Meeting power, communications, thermal and payload operation requirements
- Incorporate autonomous features to handle contingency situations
- Exploration of Mars surface features by studying the morphology, topography and mineralogy
- Study the constituents of Martian atmosphere including methane and CO2 using remote sensing techniques
- Study the dynamics of the upper atmosphere of Mars, effects of solar wind and radiation and the escape of volatiles to outer space
The mission would also provide multiple opportunities to observe the Martian moon Phobos and also offer an opportunity to identify and re-estimate the orbits of asteroids seen during the Martian Transfer Trajectory. 
- Mass: The lift-off mass was 1,337.2 kg (2,948 lb), including 852 kg (1,878 lb) of propellant.
- Bus: The spacecraft's bus is a modified I-1 K structure and propulsion hardware configuration, similar to Chandrayaan-1, India's lunar orbiter that operated from 2008 to 2009, with specific improvements and upgrades needed for a Mars mission. The satellite structure is constructed of an aluminium and composite fibre reinforced plastic (CFRP) sandwich construction.
- Power: Electric power is generated by three solar array panels of 1.8 m × 1.4 m (5 ft 11 in × 4 ft 7 in) each (7.56 m2 (81.4 sq ft) total), for a maximum of 840 watts of power generation in Mars orbit. Electricity is stored in a 36 Ah Lithium-ion battery.
- Propulsion: A liquid fuel engine with a thrust of 440 newtons (99 lbf) is used for orbit raising and insertion into Mars orbit. The orbiter also has eight 22-newton (4.9 lbf) thrusters for attitude control. Its propellant mass at launch was 852 kg (1,878 lb).
- Attitude and Orbit Control System: Maneuvering system that includes electronics with a MAR31750 processor, two star sensors, a solar panel Sun sensor, a coarse analog Sun sensor, four reaction wheels, and the primary propulsion system.
- Antennae: Low gain antenna, mid gain antenna, and high gain antenna
- Atmospheric studies: Lyman-Alpha Photometer (LAP) – a photometer that measures the relative abundance of deuterium and hydrogen from Lyman-alpha emissions in the upper atmosphere. Measuring the deuterium/hydrogen ratio will allow an estimation of the amount of water loss to outer space. The nominal plan to operate LAP is between the ranges of approximately 3,000 km (1,900 mi) before and after Mars periapsis. Minimum observation duration for achieving LAP's science goals is 60 minutes per orbit during normal range of operation. The objectives of this instrument are as follows:  Estimation of D/H ratio Estimation of escape flux of H2 corona Generation of hydrogen and deuterium coronal profiles. Methane Sensor for Mars (MSM) – was meant to measure methane in the atmosphere of Mars, if any, and map its sources with an accuracy of parts-per-billion (ppb). After entering Mars orbit it was determined that the instrument, although in good working condition, had a design flaw and it was not capable of detecting methane.  The instrument was repurposed as an albedo mapper.
- Particle environment studies: Mars Exospheric Neutral Composition Analyser (MENCA) – is a quadrupole mass analyser capable of analysing the neutral composition of particles in the range of 1–300 amu (atomic mass unit) with unit mass resolution. The heritage of this payload is from Chandra's Altitudinal Composition Explorer (CHACE) payload aboard the Moon Impact Probe (MIP) in Chandrayaan-1 mission. MENCA is planned to perform five observations per orbit with one hour per observation. 
- Surface imaging studies: Thermal Infrared Imaging Spectrometer (TIS) – TIS measures the thermal emission and can be operated during both day and night. It would map surface composition and mineralogy of Mars and also monitor atmospheric CO2 and turbidity (required for the correction of MSM data). Temperature and emissivity are the two basic physical parameters estimated from thermal emission measurement. Many minerals and soil types have characteristic spectra in TIR region. TIS can map surface composition and mineralogy of Mars.  Mars Colour Camera (MCC) – This tricolour camera gives images and information about the surface features and composition of Martian surface. It is useful to monitor the dynamic events and weather of Mars like dust storms/atmospheric turbidity. MCC will also be used for probing the two satellites of Mars, Phobos and Deimos. MCC would provide context information for other science payloads. MCC images are to be acquired whenever MSM and TIS data is acquired. Seven Apoareion Imaging of the entire disc and multiple Periareion images of 540 km × 540 km (340 mi × 340 mi) are planned in every orbit. 
Telemetry and command
The ISRO Telemetry, Tracking and Command Network performed navigation and tracking operations for the launch with ground stations at Sriharikota, Port Blair, Brunei and Biak in Indonesia, and after the spacecraft's apogee became more than 100,000 km, an 18 m (59 ft) and a 32 m (105 ft) diameter antenna of the Indian Deep Space Network were utilised. The 18 m (59 ft) dish antenna was used for communication with the craft until April 2014, after which the larger 32 m (105 ft) antenna was used. NASA's Deep Space Network is providing position data through its three stations located in Canberra, Madrid and Goldstone on the US West Coast during the non-visible period of ISRO's network. The South African National Space Agency's (SANSA) Hartebeesthoek (HBK) ground station is also providing satellite tracking, telemetry and command services.
Communications are handled by two 230-watt TWTAs and two coherent transponders. The antenna array consists of a low-gain antenna, a medium-gain antenna and a high-gain antenna. The high-gain antenna system is based on a single 2.2-metre (7 ft 3 in) reflector illuminated by a feed at S-band. It is used to transmit and receive the telemetry, tracking, commanding and data to and from the Indian Deep Space Network.
ISRO originally intended to launch MOM on its Geosynchronous Satellite Launch Vehicle (GSLV), but the GSLV failed twice in 2010 and was continuing to experience issues with its cryogenic engine. It was not advisable to wait for the new batch of rockets as that would have delayed the MOM project for at least three years, so ISRO opted to switch to the less-powerful Polar Satellite Launch Vehicle (PSLV). Since the PSLV was not powerful enough to place MOM on a direct-to-Mars trajectory, the spacecraft was launched into a highly elliptical Earth orbit and used its own thrusters over multiple perigee burns (to take advantage of the Oberth effect) to place itself on a trans-Mars trajectory.
On 19 October 2013, ISRO chairman K. Radhakrishnan announced that the launch had to be postponed by a week as a result of a delay of a crucial telemetry ship reaching Fiji. The launch was rescheduled for 5 November 2013. ISRO's PSLV-XL placed the satellite into Earth orbit at 09:50 UTC on 5 November 2013, with a perigee of 264.1 km (164.1 mi), an apogee of 23,903.6 km (14,853.0 mi), and inclination of 19.20 degrees, with both the antenna and all three sections of the solar panel arrays deployed. During the first three orbit raising operations, ISRO progressively tested the spacecraft systems.
The orbiter's dry mass is 500 kg (1,100 lb), and it carried 852 kg (1,878 lb) of fuel and oxidiser at launch. Its main engine, which is a derivative of the system used on India's communications satellites, uses the bipropellant combination monomethylhydrazine and dinitrogen tetroxide to achieve the thrust necessary for escape velocity from Earth. It was also used to slow down the probe for Mars orbit insertion and, subsequently, for orbit corrections.
Models used for MOM:
Several orbit raising operations were conducted from the Spacecraft Control Centre (SCC) at the ISRO Telemetry, Tracking and Command Network (ISTRAC) at Peenya, Bengaluru on 6, 7, 8, 10, 12 and 16 November by using the spacecraft's on-board propulsion system and a series of perigee burns. The first three of the five planned orbit raising manoeuvres were completed with nominal results, while the fourth was only partially successful. However, a subsequent supplementary manoeuvre raised the orbit to the intended altitude aimed for in the original fourth manoeuvre. A total of six burns were completed while the spacecraft remained in Earth orbit, with a seventh burn conducted on 30 November to insert MOM into a heliocentric orbit for its transit to Mars.
The first orbit-raising manoeuvre was performed on 6 November 2013 at 19:47 UTC when the spacecraft's 440-newton (99 lbf) liquid engine was fired for 416 seconds. With this engine firing, the spacecraft's apogee was raised to 28,825 km (17,911 mi), with a perigee of 252 km (157 mi).
The fourth orbit raising manoeuvre, starting at 20:36 UTC on 10 November 2013, imparted an incremental velocity of 35 m/s (110 ft/s) to the spacecraft instead of the planned 135 m/s (440 ft/s) as a result of underburn by the motor. Because of this, the apogee was boosted to 78,276 km (48,638 mi) instead of the planned 100,000 km (62,000 mi). When testing the redundancies built-in for the propulsion system, the flow to the liquid engine stopped, with consequent reduction in incremental velocity. During the fourth orbit burn, the primary and redundant coils of the solenoid flow control valve of 440 newton liquid engine and logic for thrust augmentation by the attitude control thrusters were being tested. When both primary and redundant coils were energised together during the planned modes, the flow to the liquid engine stopped. Operating both the coils simultaneously is not possible for future operations, however they could be operated independently of each other, in sequence.
As a result of the fourth planned burn coming up short, an additional unscheduled burn was performed on 12 November 2013 that increased the apogee to 118,642 km (73,721 mi), a slightly higher altitude than originally intended in the fourth manoeuvre. The apogee was raised to 192,874 km (119,846 mi) on 15 November 2013, 19:57 UTC in the final orbit raising manoeuvre.
On 30 November 2013 at 19:19 UTC, a 23-minute engine firing initiated the transfer of MOM away from Earth orbit and on heliocentric trajectory toward Mars. The probe travelled a distance of 780,000,000 kilometres (480,000,000 mi) to reach Mars.
Four trajectory corrections were originally planned, but only three were carried out. The first trajectory correction manoeuvre (TCM) was carried out on 11 December 2013 at 01:00 UTC by firing the 22-newton (4.9 lbf) thrusters for a duration of 40.5 seconds. After this event, MOM was following the designed trajectory so closely that the trajectory correction manoeuvre planned in April 2014 was not required. The second trajectory correction manoeuvre was performed on 11 June 2014 at 11:00 UTC by firing the spacecraft's 22 newton thrusters for a duration of 16 seconds. The third planned trajectory correction manoeuvre was postponed, due to the orbiter's trajectory closely matching the planned trajectory. The third trajectory correction was also a deceleration test 3.9 seconds long on 22 September 2014.
The plan was for an insertion into Mars orbit on 24 September 2014, approximately 2 days after the arrival of NASA's MAVEN orbiter. The 440-newton liquid apogee motor was test fired on 22 September at 09:00 UTC for 3.968 seconds, about 41 hours before actual orbit insertion.
The orbit insertion put MOM in a highly elliptical orbit around Mars, as planned, with a period of 72 hours 51 minutes 51 seconds, a periapsis of 421.7 km (262.0 mi) and apoapsis of 76,993.6 km (47,841.6 mi). At the end of the orbit insertion, MOM was left with 40 kg (88 lb) of fuel on board, more than the 20 kg (44 lb) necessary for a six-month mission.
On 28 September 2014, MOM controllers published the spacecraft's first global view of Mars. The image was captured by the Mars Colour Camera (MCC).
On 7 October 2014, the ISRO altered MOM's orbit so as to move it behind Mars for Comet Siding Spring's flyby of the planet on 19 October 2014. The spacecraft consumed 1.9 kg (4 lb) of fuel for the manoeuvre. As a result, MOM's apoapsis was reduced to 72,000 km (45,000 mi). After the comet passed by Mars, ISRO reported that MOM remained healthy.
On 4 March 2015, the ISRO reported that the MSM instrument was functioning normally and are studying Mars' albedo, the reflectivity of the planet's surface. The Mars Colour Camera was also returning new images of the Martian surface.
On 24 March 2015, MOM completed its initial six-month mission in orbit around Mars. ISRO extended the mission by an additional six months; the spacecraft has 37 kg (82 lb) of propellant remaining and all five of its scientific instruments are working properly. The orbiter can reportedly continue orbiting Mars for several years with its remaining propellant.
In March 2016, the first science results of the mission were published in Geophysical Research Letters, presenting measurements obtained by the spacecraft's MENCA instrument of the Martian exosphere.
On 17 January 2017, MOM's orbit was altered to avoid the impending eclipse season. With a burn of eight 22 N thrusters for 431 seconds, resulting in a velocity difference of 97.5 metres per second (351 km/h) using 20 kilograms (44 lb) of propellant (leaving 13 kg remaining), eclipses were avoided until September 2017. The battery is able to handle eclipses of up to 100 minutes.
On 19 May 2017, MOM reached 1,000 days (973 sols) in orbit around Mars. In that time, the spacecraft completed 388 orbits of the planet and relayed more than 715 images back to Earth. ISRO officials stated that it remains in good health.
On 24 September 2018, MOM completed 4 years in its orbit around Mars, although the designed mission life was only six months. Over these years, MOM's Mars Colour Camera has captured over 980 images that were released to the public. The probe is still in good health and continues to work nominally.
On 24 September 2019, MOM completed 5 years in orbit around Mars, sending 2 terabytes of imaging data, and had enough propellant to complete another year in orbit.
In 2014, China referred to India's successful Mars Orbiter Mission as the "Pride of Asia". The Mars Orbiter Mission team won US-based National Space Society's 2015 Space Pioneer Award in the science and engineering category. NSS said the award was given as the Indian agency successfully executed a Mars mission in its first attempt; and the spacecraft is in an elliptical orbit with a high apoapsis where, with its high resolution camera, it is taking full-disk colour imagery of Mars. Very few full disk images have ever been taken in the past, mostly on approach to the planet, as most imaging is done looking straight down in mapping mode. These images will aid planetary scientists.
ISRO plans to develop and launch a follow-up mission called Mars Orbiter Mission 2 (MOM-2 or Mangalyaan-2) with a greater scientific payload to Mars in 2024. The orbiter will use aerobraking to reduce apoapsis of its initial orbit and reach an altitude more suitable for scientific observation.