Mars Orbiter Mission
This is a collection of articles archived for the excellence of their content.
Mars Orbiter Mission: Timeline
Here's the timeline of Mars Orbiter Mission.
05-11-2013: PSLV-C25, in its twenty fifth flight, successfully launches Mars Orbiter Mission Spacecraft from SDSC SHAR Sriharikota
07-11-2013: The first orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 01:17 hrs(IST) on Nov 07, 2013 successfully completed
08-11-2013: The second orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 02:18:51 hrs(IST), with a burn time of 570.6 seconds successfully completed. The observed change in Apogee is from 28814 km to 40186 km
09-11-2013: The third orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 02:10:43 hrs(IST) on Nov 09, 2013, with a burn time of 707 seconds successfully completed. The observed change in Apogee is from 40186km to 71636km.
11-11-2013: In the fourth orbit-raising operation conducted on Nov 11, 2013 the apogee (farthest point to Earth) of Mars Orbiter Spacecraft was raised from 71,623 km to 78,276 km by imparting an incremental velocity of 35 metres/second (as against 130 metres/second originally planned to raise apogee to about 100,000 [1 lakh] km). The spacecraft is in normal health.
12-11-2013: Fourth supplementary orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 05:03:50 hrs(IST) on Nov 12, 2013, with a burn Time of 303.8 seconds successfully completed. The observed change in Apogee is from 78276km to 118642km.
16-11-2013: The fifth orbit raising manoeuvre of Mars Orbiter Spacecraft, starting at 01:27 hrs(IST) on Nov 16, 2013, with a burn Time of 243.5 seconds successfully completed. The observed change in Apogee is from 118642km to 192874km.
01-12-2013: Medium Gain Antenna of the Mars Orbiter Spacecraft is powered for long distance communication, subsequent to successful Trans Mars Injection (TMI) manoeuvre. Trans Mars Injection (TMI) operations completed successfully. The liquid engine burn time was 1328.89 sec and the imparted incremental velocity was 647.96 m/sec.
02-12-2013: Spacecraft has travelled a distance of 5,36,000 km by 17:00 hrs (IST) of Dec 2, 2013. It has crossed the distance to Moon's orbit around Earth (mean distance 3,85,000 km) this morning.
04-12-2013: Spacecraft has traversed beyond the Sphere of Influence (SOI) of Earth extending about 9,25,000 km at around 1:14 hrs (IST) on Dec 4, 2013.
11-12-2013: The first Trajectory Correction Manoeuvre (TCM) of Spacecraft was carried out successfully at 06:30 hrs (IST) by firing the 22 Newton Thrusters for a duration of 40.5 seconds. The spacecraft is travelling at a distance of about 29 lakh (2.9 million) km away from Earth.11-02-2014: 100 Days Of Mars Orbiter Spacecraft.
09-04-2014: Mars Orbiter Spacecraft Crosses Half Way Mark of its Journey.
12-06-2014: The second Trajectory Correction Manoeuvre (TCM-2) of India's Mars Orbiter Spacecraft was successfully performed on June 11, 2014 at 1630 hrs IST. TCM-2 was performed by firing the spacecraft's 22 Newton thrusters for a duration of 16 seconds.
16-09-2014: Time-tagged commands to execute Mars Orbit Insertion (MOI) uploaded.
17-09-2014: Uploading of commands for Fourth Trajectory Correction Manoeuver and test-firing of Main Liquid Engine (scheduled for Sep 22, 2014) is in progress.
22-09-2014: Test Firing of Main Liquid Engine of Mars Orbiter Spacecraft is successful.
24-09-2014: Mangalyaan enters Mars orbit.
India created history on September 24, becoming the first country to successfully get a spacecraft into the Martian orbit on its maiden attempt. Here are 10 things you should know about the Mars Orbiter Mission or Mangalyaan. 1. Before India, various countries have launched Mars missions, but out of the 51 attempts, only 21 were successful. India now joins the Martian club that comprises the US, Russia and the European Space Agency.
2. US space agency Nasa was one of the first to congratulate Isro on its success. Prime Minister Narendra Modi gave a congratulatory speech highlighting the success and hardwork of the Isro scientists.
3. After the Mars mission, the Indian space agency will work together with Chinese space scientists to prepare a roadmap for a series of missions to be implemented together. Isro chief's K Radhakrishnan's tenure will come to an end by the time of 2014. The first three months of 2015 might see Radhakrishnan practice Kathakali.
4. A methane sensor will look for sources of the gas. While the Mars colour camera clicks away, a thermal infrared spectrometer will study heat emission, minerals and soil on Mars.
5. India's MOM is the cheapest inter-planetary mission. It cost about a tenth of Nasa's Mars mission Maven that entered the Martian orbit on September 22. PM Narendra Modi applauding Indian scientists had said,"Hollywood movie Gravity costs more than our space mission."
6. The spacecraft structure and propulsion hardware configurations are similar to Chandrayaan 1, which was country’s first successful robotic lunar probe. Specific improvements and upgrades were made for a Mars specific mission.
7. The most important experiment is to check for the presence of methane that can indicate just what kind of life existed on Mars, if at all.
8. The orbiter, after a 300-day flight, has covered a distance of 680 million kilometres to reach the Red Planet's orbit.
9. As it goes around Mars on an elliptical orbit with the closest point around 420km and the farthest around 80,000km, MOM will employ five equipment that collectively weight 15kg to do scientific studies.
10. The spacecraft trajectory would be tracked from Nasa's Jet Propulsion Laboratory facilities at Goldstone (US), Madrid (Spain) and Canberra (Australia).
Amount spent on Mars Orbiter Mission
The Indian Space Research Organization (Isro), which, according to all official claims, is reported to have spent Rs 450 crore on the Mars Orbiter Mission (MOM), did not even spend the whole of that shoestring budget.
An austere Isro managed to save Rs 2.61 crore which it promptly returned to the Centre, reaffirming MOM to be the world's cheapest mission to the red planet, at a cost of Rs 447.39 crore.
Documents revealing the audited expenditure of all Isro projects in the last five years reveal that MOM isn't the only such project.
Though Isro sought Rs 892.69 crore to launch the GSAT-15 communication satellite, the Centre released on ly Rs 830.88 crore. But Isro, which launched GSAT-15 last November, completed the project using just Rs 806.4 crore, saving Rs 24.48 crore. Similarly, it had sought Rs 897.94 crore for GSAT-16 but got only Rs 865 crore and the space agency went on to complete the project with Rs 864.12 crore.
“Unlike the Mars mission, which was a one-time project when cleared, the GSAT programme envisages launching several more satellites. Therefore, the money saved from its launch is with Isro to be used for future satellites,“ a senior official said.
How costs were minimised
India's space programme has succeeded at the first attempt where others have failed - by sending an operational mission to Mars.
The Mangalyaan satellite was confirmed to be in orbit shortly after 0800, Indian time. It is, without doubt, a considerable achievement.
This is a mission that has been budgeted at 4.5bn rupees ($74m), which, by Western standards, is staggeringly cheap.
The American Maven orbiter that arrived at the Red Planet on Monday is costing almost 10 times as much.
Back in June, Indian Prime Minister Narendra Modi even quipped that India's real-life Martian adventure was costing less than the make-believe Hollywood film Gravity.
Even Bollywood sci-fi movies like Ra.One cost a good chunk of what it has taken to get Mangalyaan to Mars.
So how has India done it? For sure, people costs are less in this populous nation, and the scientists and engineers working on any space mission are always the largest part of the ticket price. Home-grown components and technologies have also been prioritised over expensive foreign imports.
But, in addition, India has been careful to do things simply.
"They've kept it small. The payload weighs only about 15kg. Compare that with the complexity in the payload in Maven and that will explain a lot about the cost," says Britain's Prof Andrew Coates, who will be a principal investigator on Europe's Mars rover in 2018.
"Of course, that reduced complexity suggests it won't be as scientifically capable, but India has been smart in targeting some really important areas that will complement what others are doing." Mangalyaan has gone equipped with an instrument that will try to measure methane in the atmosphere.
This is one of the hottest topics in Mars research right now, following previous, tantalising observations of the gas.
Earth's atmosphere contains billions of tonnes of methane, the vast majority of it coming from microbes, such as the organisms found in the digestive tracts of animals.
The speculation has been that some methane-producing bugs, or methanogens, could perhaps exist on Mars if they lived underground, away from the planet's harsh surface conditions.
It is a fascinating prospect.
So, even though Mangalyaan has a small payload, it will actually address some of the biggest questions at the Red Planet.
Western scientists are excited also to have the Indian probe on station.
Its measurements of other atmospheric components will dovetail very nicely with Maven and the observations being made by Europe's Mars Express. "It means we'll be getting three-point measurements, which is tremendous," says Prof Coates.
This will enable researchers to better understand how the planet lost the bulk of its atmosphere billions of years ago, and determine what sort of climate it could once have had, and whether or not it was conducive to life.
I have read a lot about the criticism of Mangalyaan and India's space programme.
There's an assumption among many, I guess, that space activity is somehow a plaything best left to wealthy industrial countries; that it can have no value to developing nations.
The money would be better spent on healthcare and improved sanitation, so the argument goes.
But what this position often overlooks is that investment in science and technology builds capability and capacity, and develops the sort of people who benefit the economy and society more widely.
Space activity is also a wealth generator. Some of the stuff we do up there pays for stuff down here.
The industrialised nations know it; that's one of the reasons they invest so heavily in space activity.
Consider just the UK. It has dramatically increased its spending on space in recent years.
The government has even identified satellites as being one of the "eight great technologies" that can help rebalance the UK economy and drive it forward.
India wants a part of this action, too, and in Mangalyaan and its other satellite and rocket programmes, the nation is putting itself into a strong position in international markets for space products and services.
ISRO Mangalyaan mission achieved success on September 24, 2014. Here's a look at the timeline of events behind it and the people that made the mission a reality.
On September 24, 2014, India created history when it achieved success with its first-ever Mars mission, Mangalyaan. The mission was launched by ISRO on November 5, 2013, onboard PSLV-C25 rocket which took the Mars Orbiter into space on its twenty-fifth flight.
The mission was launched from the first launch pad at Satish Dhawan Space Centre SHAR, Sriharikota and has since remained in the planet's orbit, outliving its initial mission life of 6 months.
Mangalyaan's flight of great significance to the nation as it not only became India's first interplanetary mission but also made it the first Asian nation to reach Mars' orbit and more importantly, the first nation in the world to do so on its first attempt.
The team involved in India's Mangalyaan Mars mission
While much has been talked about the team of women who helped make the Mangalyaan mission a reality, it is also worth taking a look at others who made the Mars mission possible.
K Radhakrishnan lead the mission and oversaw the activities of ISRO as well as the mission.
S Ramakrishnan was a Director who helped in Development of the PSLV and liquid propulsion system.
P. Kunhikrishnan was a Project Director in the PSLV programme. He was also a Mission director of PSLV-C25/Mars Orbiter Mission.
Moumita Dutta was the Project manager of the Mangalyaan mission.
Nandini Harinath was the Deputy Operations Director of Navigation.
Ritu Karidhal was the Deputy Operations Director of Navigation.
BS Kiran was the Associate Project Director of Flight dynamics.
V Kesava Raju was the Mission Director at the Mars Orbiter Mission.
V Koteswara Rao was ISRO scientific secretary.
Chandradathan was the Director of the Liquid Propulsion system.
AS Kiran Kumar was the Director of the Satellite Application Centre.
M Annadurai was the Programme Director and in charge of budget management as well as direction for spacecraft configuration, schedule and resources.
MYS Prasad: Director at Satish Dhawan Space Centre. He was also the Chairman at Launch Authorisation Board.
SK Shivakumar was a Director at ISRO Satellite Centre. He was also a Project Director for Deep Space Network antenna.
S Arunan was a Project Director at Mars Orbiter Mission and he led the team to build the spacecraft.
B Jayakumar was an Associate Project Director at the PSLV programme who was responsible for testing the rocket systems.
MS Pannirselvam was the Chief General Manager at the Sriharikota Rocket port and was the man tasked to maintain launch schedules.
Mangalyaan 2 cost
While a remarkable scientific achievement in itself, the biggest reason that Mangalyaan was such a big deal was because of how little money it cost to make it. As opposed to Mars and deep space missions from other space agencies such as NASA and Roscosmos, ISRO's Mangalyaan was built at a fraction of the cost.
Budgeted at around $75 million, Mangalyaan mission cost just 11 per cent of NASA's MAVEN orbiter, which cost somewhere in the region of $485 million to develop — and around $187 million for the launch into space and further ground support. The mission was so cost-effective that it even forced Prime Minister Narendra Modi to quip that India's real-life Mars mission costs less than the Hollywood film Gravity.
The real women of MOM
While the women of "Mission Mangal" may have been fictional, they represented the real women behind India's first mission to Mars. The mission that, in just 18 months and with a budget of only $74 million (less than the budget of the film "The Martian"), placed a satellite in orbit around Mars. The team worked anywhere from 10 to 14 hours a day to complete the seemingly impossible mission.
Ritu Karidhal, an aerospace engineer and senior scientist at ISRO who served as the deputy operations director for MOM, has worked at the space agency for over 20 years. Karidhal went on to become the mission director of ISRO's Chandrayaan-2 mission.
Nandini Harinath, a rocket scientist at ISRO, has worked on 14 missions over a span of 20 years at the agency. Harinath took an early interest in science after being exposed to "Star Trek" as a child.
Anuradha T.K., the senior-most woman in an officer position at ISRO, is a scientist who specializes in sending communications satellites to space. She has worked at the agency for almost 40 years, and is considered by many at ISRO to be a role model as a successful woman in science, according to the BBC.
Minal Rohit, a systems engineer at ISRO, was another instrumental scientist in ISRO's MOM. Moumita Dutta, another critical member of the MOM team, is a physicist who works at the Space Applications Centre (SAC) at ISRO. Dutta worked as project manager for the Methane Sensor for Mars (MSM) and developed, optimized and calibrated an optical system for the satellite.
Mission Mangal reviewed by a Mangalyaan team member
I work in ISRO and watched the movie on the first day , out of sheer curiosity. The trailer sucked, and my colleagues were fuming over it. I wished the movie wouldn't be that bad, and thought of giving it a try.
As a Mangalyaan mission team member , I felt proud of ourselves watching the movie. The movie boosts up the morale of the employees of ISRO and also gives the younger generation something to look up to.
It shows the difficulties faced by women in this organisation wherein many of them are struggling everyday to bring about work life balance.
Finally there is someone to speak for us, to tell the world that we do not have the typical government culture with 9to5 working hours. We toil hard, stay till late night, work on weekends and holidays for every other Mission, if the schedule calls for it.
The animation and the sound effects of the rocket launch and satellite scenes were fantastic.
There were a LOT of technical mistakes in the movie. Let me list them out, as far I could remember.
Firstly, the mangalyaan carrying rocket which they called as “PSLV" , isn't the structure of PSLV. PSLV is 4STO vehicle, with only solid and liquid stages. But whatever rocket they showed, seemed to have a cryo stage and with 3STO configuration. I felt it was a blatant error.
Before every launch there are so many planned activities and tests that have to be executed prior to going on automatic launch sequence mode. You can't just abort the launch, pack off home and then come back and launch the vehicle by just turning on a few switches. Even launch abort is a huge procedure in itself, taking hours to undo things including venting out all the propellants. And how did Vidya balan manage to fly back and forth between Bangalore and Shriharikota in the same day?
During one of the orbit raising maneuvers, the LAM engine failed to fire. But nobody analysed what went wrong? How could one be sure that it'd fire the next time? ISRO never ever proceeds without thoroughly analysing reasons for failure. Never. I felt that was a loose end.
Mars has got prograde orbit just as Earth. Mangalyaan was launched in a prograde orbit with Mars. But what they showed in the animation seemed like retrograde orbit. (In the scenes before and after occultation).
I think I saw animation of solar panel and antenna deployment after the satellite gets into transplanetary orbit. This is completely absurd(if so). solar panels deploy soon after satellite is injected into space.
That's all I could remember now, which means there are more technical mistakes. On the non technical side, Kritika goes absent from office for nearly a month without any notice?? And she just joins back and her reporting officer Tara welcomes with hip-shaking dance. Wow! Wish my boss ever did that!!
I felt that if only the film crew had done some more home work and got their basics right, it would have been far better outcome. The subject they took in hand had lot of scope in it and all the director had to do was to spoil it with the usual Bollywood style narrative.
On a lighter note, we scientists do not clean, mop and paint our offices. We have staff for that. We already have got enough on our plates.
What MOM accomplished
Mars Orbiter Mission (MOM), the maiden interplanetary mission of ISRO, launched on November 5, 2013 by PSLV-C25 got inserted into Martian orbit on September 24, 2014 in its first attempt. MOM completes 1000 Earth days in its orbit, today (June 19, 2017) well beyond its designed mission life of six months. 1000 Earth days corresponds to 973.24 Mars Sols (Martian Solar day) and MOM completed 388 orbits.
MOM is credited with many laurels like cost-effectiveness, short period of realisation, economical mass-budget, miniaturisation of five heterogeneous science payloads etc. Satellite is in good health and continues to work as expected. Scientific analysis of the data received from the Mars Orbiter spacecraft is in progress.
ISRO has also launched MOM Announcement of Opportunity (AO) programmes for researchers in the country to use MOM data for R&D. The success of Mars Orbiter Mission has motivated India’s student and research community in a big way. Thirty-two proposals were supported under this AO. A Planetary data analysis workshop was also conducted to strengthen the MOM-AO scientist's research interest.
First year data from MOM was released to public on September 24, 2016 through ISSDC website. There are 1381 registered users and 370 GB data has been downloaded.
The Mars Colour Camera, one of the scientific payloads onboard MOM, has produced more than 715 images so far. Mars Atlas was prepared and made available on ISRO website.
MOM went through a communication 'blackout' as a result of solar conjunction from June 2, 2015 to July 2, 2015. Telemetry data was received during most of the conjunction period except for 9 days from June 10-18, during superior conjunction. MOM was commanded with autonomy features starting from May 18, 2015, which enabled it to survive the communication 'blackout' period without any ground commands or intervention. The spacecraft emerged out of 'blackout' period with auto control of the spacecraft systems successfully. This experience had enabled the mission team to program a spacecraft about one month in advance for all operations.
MOM spacecraft experienced the ‘whiteout’ geometry during May 18 to May 30, 2016. A ‘whiteout’ occurs when the Earth is between the Sun and Mars and too much solar radiation may make it impossible to communicate with the Earth. The maximum duration of ‘whiteout’ is around 14 days. MOM spacecraft experienced the ‘whiteout’ during May, 2016. However, MOM is built with full autonomy to take care of itself for long periods without any ground intervention. The entire planning and commanding for the ‘whiteout’ was completed 10 days before the actual event. No commanding was carried out on the satellite in the ‘whiteout’ period. Payload operations were suspended. Fault Detection, Isolation and Recovery were kept enabled, so as to take care of any contingency on the spacecraft. Master Recovery Sequencer was programmed, to acquire the attitude of the spacecraft and ensure communication with earth even in case of loss of attitude. The spacecraft came out of ‘whiteout’ geometry successfully on May 30, 2016 and has been normalised for regular operations.
An orbital manoeuvre was performed on MOM spacecraft to avoid the impending long eclipse duration for the satellite. The duration of the eclipse would have been as long as 8 hours. As the satellite battery is designed to handle eclipse duration of only about 1 Hour 40 minutes, a longer eclipse would have drained the battery beyond the safe limit. The manoeuvres performed on January 17, 2017 brought down the eclipse duration to zero during this long eclipse period. On the Evening of January 17, all the eight numbers of 22N thrusters were fired for a duration of 431 seconds, achieving a velocity difference of 97.5 m/s. This has resulted in a new orbit for the MOM spacecraft, which completely avoided eclipse up to September 2017. About 20 kg propellant was consumed for this manoeuvres leaving another 13 kg of propellant for its further mission life.
Major results from the five scientific payloads on MOM are summarised:
Methane Sensor for Mars (MSM)
The Methane Sensor for Mars (MSM) on-board Mars Orbiter Mission (MOM) is designed to measure total column of methane in the Martian atmosphere. It is a differential radiometer based on Fabry-Perot Etalon (FPE) Filters. Emission of methane from Mars in recent times has been detected at few ppb level and is sporadic and random in location. Though MSM could not detect any methane (above its sensitivity limit), it provided excellent reflectance data of Mars surface in the 1.65µm region.
With 20 bit resolution and SNR>7000, radiometric performance of MSM is extremely good. It is found that during the last 1000 days of operation radiometric calibration of the instrument remained very stable. Figure 1 gives the reflectance map of Mars generated from reference channel data of MSM which is corrected for radiometric errors and CO2 absorption. This data together with reflectance data derived from three visible spectral bands of Mars Colour Camera (MCC) is useful in studying the mineralogy of Mars surface. MSM data has also been used is altudying the dust and cloud properties of Martian atmosphere. This is the first time a near global albedo map of Mars has been prepared using 1.65 µm wavelength (SWIR region) of EM spectra.
The Mars Color Camera (MCC)
The Mars Color Camera (MCC) onboard MOM has 16 different modes of exposures, aimed at imaging the Mars surface for Morphological / Structural mapping, imaging dynamic events viz. Polar Ice cap, clouds, Dust storms and other opportunistic imaging. Analysis of these payloads have churned interesting results -
A) Atmospheric Optical Depth estimation in Valles Marineris using Mars Colour Camera
Atmospheric optical depth (AOD) was estimated through an experiment involving multi-view / multi-optical path length images of Mars Colour Camera (MCC) in the Valles Marineris on Mars. The same was used to determine the pressure scale height of the dust (11.24 km) which is commensurate with the known GSM scale height computation (11.2 -12.1 km) (Icarus, 2016).
B) Imaging of far side of Deimos by MCC:
The highly elliptical and eccentric orbit of the MOM mission has provided the unique opportunity to view the far side of Deimos, the farthest of the two natural satellites of Mars. This is not possible by any of the contemporary orbiters on Mars from international mission presently operational in Martian orbit. The same has been proved using orbital simulations, shape models and estimation of the apparent magnitude (14.06) (Planetary and Space Science, 2015).
C) Morphology study of Ophir Chasma on Mars using MCC data
Ophir Chasma located in the central Valles Marineris has been imaged by MOM at a high resolution of 19.5 m, a geological map has been prepared, various morphological units have been delineated. The various morphological features like- spur and gullies present prominently on the Chasma walls, ridges which covers the northern depression, layered domes, and dark mineral deposits were mapped. Two types of layered deposits are identifiable and exposed i.e. in the canyon walls (low albedo) & Ophir Mensa (high albedo).
D) Types of clouds on various Mons using Mars colour camera
Mars colour camera (MCC) onboard Mars Orbiter Mission (MOM) observed ASTER clouds over Olympus and Elysium Mons, that have unique morphology and sometimes forms rays around the central disk of the Mountain. The Aster clouds are thought to form under weak atmospheric static stability and weak background flow, and are probably related to the local up-slope winds associated with the Mons. These clouds are observed during mid to late northern summer on western side of Olympus Mons (A & B images below).
MCC has also observed Lee-Wave cloud over Ascraeus Mons, Mars. Lee wave clouds are a regular train of clouds aligned orthogonal to the prevailing wind. Mountain waves (lee waves, or gravity waves) result from a parcel of air being forced up due to a topographic high, condensing out as a cloud, then dropping back down (C & D images below) . Other than Lee-wave Clouds, Mars colour camera (MCC) onboard Mars Orbiter Mission (MOM) observed ASTER clouds over Olympus and Elysium Mons, that have unique morphology and sometimes forms rays around the central disk. These clouds are observed during mid to late northern summer (A & B images below).
Besides, the shadow of clouds casted on the Martian surface have also been used to estimate the cloud height and one such patch of cloud is estimated to be at an altitude of about 35-38 km. Which is abode of CO2 clouds (LPSC 2015).
E)Automatic extraction, monitoring and change detection of area under Polar Ice Caps on Mars:
Also long term change detection (four decades) was done by comparing snow/ice area from MCC images with Viking images. MCC showed a range 6,33,825 km2 to 9,52,700 km2 during imaging period, while during same imaging season of Viking mosaic (1976 to 1980) showed snow/ice area to be approximately 7,83,412 km2 which is within the range calculated by MCC.
Mars Exospheric Neutral Composition Analyser (MENCA)
The outermost region of a planetary atmosphere — called exosphere — holds the secrets to the atmospheric escape and evolution. This is the region being explored by Mars Exospheric Neutral Composition Analyser (MENCA) experiment aboard the Mars Orbiter Mission (MOM), which is a quadrupole mass spectrometer based payload, developed at the Space Physics Laboratory of Vikram Sarabhai Space Centre, measuring neutral gases in the mass range of 1 to 300 amu. MENCA has successfully studied the distribution of the major species in the Martian exosphere, which has helped understand the solar forcing on the Martian atmosphere.
MENCA has provided the first measurements of the low-latitude evening time exosphere of Mars (Fig.1). The measured abundances of the four major Martian exospheric gases, viz. atomic Oxygen (16 amu), molecular Nitrogen and Carbon-Monoxide (28 amu), and Carbon-Dioxide (44 amu), during December 2014, showed significant orbit-to-orbit variability. These observations correspond to moderate solar activity conditions, during perihelion season (when Mars is closest to Sun) and when MOM’s periapsis altitude was the lowest (~265 km). MENCA observations have shown for the first time that the abundance of Oxygen exceeds that of Carbon-Dioxide at an altitude of ~270 ±10 km, during the perihelion evening hours. This result indicate that the altitude where O/CO2 ratio exceeds 1 is a highly variable, is much different than at noon, and therefore it is an important input for constraining the EUV forcing in the models dealing with upper atmosphere of Mars. From the variation of the abundances of different gases with altitude, the temperature of the Martian exosphere was found to be about 270 ±5 K, during perihelion season.
Another major result from MENCA is the discovery of 'hot' (suprathermal) Argon in the exosphere of Mars (Fig. 2). The word 'hot' or 'suprathermal' indicates that the atoms are more energetic compared to the thermal population, and hence their kinetic temperatures are higher. The upper limit of Ar number density corresponding to the December 2014 period is ~5 × 10 5 cm −3 (at ~250 km), and the typical scale height is about 16 km, corresponding to an exospheric temperature of around 275 K. However, on few orbits, the scale height over this altitude region is found to increase significantly making the effective temperature greater than 400 K: clearly indicating the presence of suprathermal Argon in the Martian exosphere. The detection of these hot particles has important implications in the context of understanding the energy deposition in the Martian upper atmosphere, and will help understand why the Martian atmospheric escape rates are higher than what was believed previously.
Thermal infrared Imaging Spectrometer (TIS)
The Thermal infrared Imaging Spectrometer (TIS) is one of the five instruments onboard Indian Mars Orbiter Mission (MOM) that measures emitted thermal Infrared radiation while orbiting around Mars in elliptical orbit. TIS is a plane reflection grating based infrared spectrometer which uses an un-cooled micro-bolometer detector operating in 7μm to 13μm wavelength range.
Elliptical orbit of MOM provides unique opportunity for scanning of full Mars disk from apoapsis at coarse spatial resolution and site specific surface imaging at high spatial resolution in push broom mode from periapsis. TIS has carried out more than 90 imaging sessions over Martian surface as shown in Fig 1. Observed brightness temperatures were found to be related with surface temperature, emissivity, viewing geometry and atmospheric conditions.
A scene-level analysis showed a gradual increase in binned scene-level Brightness temperature (BT) at 10.25 μm with increase in areocentric longitude (Ls). BT were relatively higher during Ls 2600 to 3390 as compared to values during Ls 2040 to 2600. Measurements carried out during higher Sun elevation were found associated with higher BT as compared to observations from low Sun elevation angles for similar viewing geometry as shown in figure 2.
Imaging sessions were carried out (a) from apoapsis covering Martian disk and (b) site specific imaging from periapsis. Observed BT from an altitude of 52689 km at 12.75 µm showed warmer Southern hemisphere of Mars (on Ls=210.7 degrees) as compared to northern region. High albedo regions of Arabia terra and Isidis and low albedo region of Syrtis Major as seen in the synchronous image acquired from Mars Colour Camera (MCC) onboard the MOM mission is also shown in figure 3.
Imaging in periapsis from the altitude of 386 km near Holden crater on Ls:299.2 degrees showed variation of Brightness temperature from 278K to 291K at 10.25 μm. TIS observations are draped on background of MCC data as ancillary source of information. Emissivity spectra retrieved from TIS observation near Holden crater indicated characteristic dip between 9 to 10 μm showing the basaltic surface associated with atmospheric dust. Above findings from TIS involved detailed physics-based correction procedures including instrument thermal background, atmospheric contribution, solar and viewing geometry etc.
Lyman Alpha Photometer (LAP)
LAP, one of the five scientific instruments of MOM spacecraft’s payload suite developed at LEOS_ISRO, is the first Indian space-borne absorption gas cell photometer that operates on the principle of resonant scattering and resonance absorption at Lyman-Α wavelengths of Hydrogen (121.567 nm) and Deuterium (121.534 nm) respectively. This type of instrument is best suited to measure the line-of-sight Lyman alpha intensity of Hydrogen and Deuterium and thereby the D/H ratio (Deuterium to Hydrogen ratio) estimation of a planet’s atmosphere. LAP can measure the amount of Deuterium compared to the amount of Hydrogen in Mars exosphere. Till date LAP instrument has been operated on-board successfully for more than 150 times (the 1st operation was carried out on 6th February, 2014 at 09:45:00 UT) during various phases of spacecraft’s journey, namely, cruise-phase, comet-phase (Siding Spring C-2013/A, 19th October, 2014 at 18:27:13 UT), Martian orbit phase (from 30th September, 2014 till date) deep-space observations (6th November, 2014 at 10:19:01 UT) for assessment of payload dark count measurements and stellar source observations (3rd February, 2016 at 14:45:00 UT) to perform on-board photometric calibration.
Figure-1 shows the generated radial profiles based on the 1st year’s MOM data. The inset in Fig 1 depicts MOM orbit geometry and LAP line of sight observation during the operation carried out during April 2015 which resulted in maximum Lyman alpha brightness. Figure 2 shows the simulated LAP observational trace covering sun-lit disk and bright limb of Mars.
Useful scientific data sets are received and are currently under analysis. Analyzed data so far has revealed successful registration of the Hydrogen Lyman-Α brightness as well as clear Hydrogen Lyman-Α flux absorption signatures of Martian atmosphere. Maximum Lyman-Α response was recorded in the zone very close to the bright limb of Martian disc.