Mars Orbiter Mission

Facts

History

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. The government of India approved the project on 3 August 2012, after the Indian Space Research Organisation completed ₹125 crore (US$19 million) of required studies for the orbiter. The total project cost may be up to ₹454 crore (US$67 million). The satellite costs ₹153 crore (US$23 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 2013 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, 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, Bangalore, 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.

Cost

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 significantly less complicated payload than NASA's MAVEN.

Mission objectives

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.

Primary objectives

The main objectives are to develop the technologies required for designing, planning, management and operations of an interplanetary mission comprising the following major tasks:

Scientific objectives

The scientific objectives deal with the following major aspects:

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.

Spacecraft design

Payload

The 15 kg (33 lb) scientific payload consists of five instruments:

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

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.

Launch

As originally conceived, ISRO was to launch MOM on its Geosynchronous Satellite Launch Vehicle (GSLV), but as the GSLV failed twice in 2010 and ISRO was continuing to sort out 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. 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.

Orbit raising manoeuvres

Several orbit raising operations were conducted from the Spacecraft Control Centre (SCC) at the ISRO Telemetry, Tracking and Command Network (ISTRAC) at Peenya, Bangalore 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 lb_f) 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 second orbit raising manoeuvre was performed on 7 November 2013 at 20:48 UTC, with a burn time of 570.6 seconds resulting in an apogee of 40,186 km (24,970 mi).

The third orbit raising manoeuvre was performed on 8 November 2013 at 20:40 UTC, with a burn time of 707 seconds, resulting in an apogee of 71,636 km (44,513 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.

Trans-Mars injection

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.

Trajectory correction manoeuvres

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 lb_f) 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.

Mars orbit insertion

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 successfully test fired on 22 September at 09:00 UTC for 3.968 seconds, about 41 hours before actual orbit insertion.

After these events, the spacecraft performed a reverse manoeuvre to reorient from its deceleration burn and successfully entered Martian orbit.

Status

The orbit insertion put MOM in a highly elliptical orbit around Mars, 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 MOM's methane sensors were 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.

A 17-day communications blackout occurred from 6 to 22 June 2015 while Mars' orbit took it behind the Sun from Earth's view.

On 24 September 2015, ISRO released its "Mars Atlas", a 120-page scientific atlas containing images and data from the Mars Orbiter Mission's first year in orbit.

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 will be avoided until September 2017. The battery is able to handle eclipses of up to 100 minutes.

Recognition

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.

An illustration of the Mars Orbiter Mission spacecraft is featured on the reverse of the ₹2,000 currency note of India.

Follow-up mission

ISRO plans to develop and launch a follow-up mission called Mangalyaan 2 with a greater scientific payload to Mars by 2020. The mission will consist of an orbiter, and will not include a lander or rover as suggested earlier. Mangalyaan 2 will be launched after the Chandrayaan 2 Moon mission scheduled for December 2018.