CHAPTER 1INTRODUCTION TO MANGALYAAN
1.1 INTRODUCTIONThe Mars Orbiter Mission (MOM) also called
Mangalyaan (Mars-craft from Sanskrit mangala, Mars and Yana, craft,
vehicle), is a spacecraft orbitingMarssince 24 September 2014. It
was launched on 5 November 2013 by theIndian Space Research
Organization(ISRO) under the guidance of the Project Director
Mylswamy Annadurai. The mission is a "technology demonstrator
project to develop the technologies for design, planning,
management, and operations of an interplanetary mission.It carries
five instruments that will help advance knowledge about Mars to
achieve its secondary, scientific, objective. The Mars Orbiter
Mission probe lifted-off from theFirst Launch PadatSatish Dhawan
Space Centre(Sriharikota Range SHAR),Andhra Pradesh, using aPolar
Satellite Launch Vehicle(PSLV) rocket C25 at 09:08 UTC (14:38 IST)
on 5 November 2013.Thelaunch windowwas approximately 20 days long
and started on 28 October 2013.The MOM probe spent about a month
ingeocentric,low-Earth orbit, where it made a series of seven
altitude-raisingorbital maneuversbeforetrans-Mars injectionon 30
November 2013 (UTC). After a 298-day transit to Mars, it was
successfully inserted into Mars orbit on 24 September 2014.It
isIndia's first interplanetary missionandISROhas become the
fourthspace agencyto reach Mars, after the Soviet space
program,NASA, and theEuropean Space Agency.It is also the first
nation to reachMars orbit on its first attempt, and the first Asian
nation to do so. The spacecraft is currently being monitored from
the Spacecraft Control Centre atISRO Telemetry, Tracking and
Command Network(ISTRAC) inBangalorewith support fromIndian Deep
Space Network(IDSN) antennae at Byalalu.
Fig 1.1 Artists Rendering of MOM orbiting MARS1.2 HISTORYThe MOM
mission concept began with a feasibility study in 2010, after the
launch of lunar satelliteChandrayaan-1in 2008. Thegovernment of
Indiaapproved the project on 3 August 2012,after theIndian Space
Research Organizationcompleted125crore(US$20million) of required
studies for the orbiter. The total project cost may
be454crore(US$74million).The satellite costs153crore(US$25million)
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 thePacific Ocean.Launch opportunities for a
fuel-savingHohmann transfer orbitoccur every 26 months, in this
case, 2016 and 2018.The Mars Orbiter's on-orbit mission life is
six-to-ten months.Assembly of the PSLV-XL launch vehicle,
designated C25, started on 5 August 2013.The mounting of the five
scientific instruments was completed atISRO 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 theUS federal government shutdown,
NASA reaffirmed on 5 October 2013 it would provide communications
and navigation support to the mission.During a meeting in 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 betweenMAVENorbiter
and MOM, as well as other current and future Mars missions.
TheISROplans to send a follow-up mission with a greater
scientificpayloadto Mars in the 20172020 timeframe; it would
include an orbiter and a stationary lander. 1.3 COSTThe total cost
of the mission was approximately450Crore(US$73 million),making it
the least-expensive Mars mission to date .The low cost of the
mission was ascribed by Kopillil Radhakrishnan, the chairman of
ISRO, to various factors, including a "modular approach", a small
number of 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'sMAVEN.An opinion piece inThe
Hindupointed out that the cost was equivalent to less than a single
bus ride for each of India's population of 1.2 billion.
1.4 OBJECTIVESThe primary objective of the Mars Orbiter Mission
is to showcase India's rocket launch systems, spacecraft-building
and operations capabilities.Specifically, the primary objective is
to develop the technologies required for design, planning,
management and operations of aninterplanetary mission, comprising
the following major tasks: design and realization of a Mars orbiter
with a capability to perform Earth-bound maneuvers, cruise phase of
300 days, Mars orbit insertion / capture, and on-orbit phase around
Mars; deep-space communication, navigation, mission planning and
management; Incorporate autonomous features to handle contingency
situations.The secondary objective is to explore Mars Surface
features, morphology, mineralogy and Martian atmosphere using
indigenous scientific instruments.1.5 SPAECRAFT SPECIFICATION
Mass:The lift-off mass was 1,350kg (2,980lb), including 852kg
(1,878lb) of propellant. Bus:The spacecraft'sbusis a modifiedI-1
Kstructure and propulsion hardware configuration, similar
toChandrayaan 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 aluminium and
composite fibre reinforced plastic (CFRP) sandwich construction.
Power:Electric power is generated by threesolar arraypanels of 1.8m
1.4m (5ft 11in 4ft 7in) each (7.56m2(81.4sqft) total), for a
maximum of 840 watts of power generation in Mars orbit. Electricity
is stored in a 36AhLi-ion battery. Propulsion:A liquid fuel engine
with a thrust of 440Newtonis used for orbit raising and insertion
into Mars orbit. The orbiter also has eight 22-newton thrusters
forattitude control.Its propellant mass is 852kg.
1.6 PAYLOADSThe 15kg (33lb) scientific payload consists of five
instruments: Mars Orbiter Mission carries five scientific payloads
to observe Martian surface, atmosphere and exosphere extending up
to 80,000 km for a detailed understanding of the evolution of that
planet, especially the related geologic and the possible biogenic
processes on that interesting planet. These payloads consist of a
camera, two spectrometers, a radiometer and a photometer. Together,
they have a weight of about 15 kg.
Figure 1.2: Design of MOM Spacecraft showing payloads at their
respective mounting locations
1.7 TELEMETRY AND COMMANDTheIndian Space Research Organization
Telemetry, Tracking and Command Networkperformed navigation and
tracking operations for the launch with ground stations
atSriharikota,Port Blair,BruneiandBiakinIndonesia,and after the
spacecraft'sapogeebecame more than 100,000km, an 18-metre (59ft)
and an 32m (105ft) diameter antenna of theIndian Deep Space
Networkwere utilized.The 18-metre (59ft) dish-antenna was used for
communication with the craft until April 2014, after which the
larger 32m (105ft) antenna was used.NASA's Deep Space Networkis
providing position data through its three stations located
inCanberra, MadridandGoldstoneon the US West Coast during the
non-visible period of ISRO's network. TheSouth African National
Space Agency's (SANSA) Hartebeesthoek(HBK) ground station is also
providing satellite tracking, telemetry and command services. 1.8
COMMUNICATIONCommunications are handled by two 230-wattTWTAsand
twocoherent transponders. The antenna array consists of alow-gain
antenna, a medium-gain antenna and ahigh-gain antenna. The
high-gain antenna system is based on a single 2.2-metre (7ft 3in)
reflector illuminated by a feed atS-band. It is used to transmit
and receive the telemetry, tracking, commanding and data to and
from theIndian Deep Space Network.1.9 LAUNCHAs originally
conceived, ISRO would have launched MOM on itsGeosynchronous
Satellite Launch Vehicle(GSLV),but as the GSLV failed twice in 2010
and ISRO was continuing to sort out issues with itscryogenic
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-powerfulPolar Satellite
Launch Vehicle(PSLV). There is no way to launch on a direct-to-Mars
trajectory with the PSLV as it does not have the thrust required.
Instead, ISRO would first launch it into Earth orbit and slowly
boost toward an interplanetary trajectory using multiple perigee
burns to maximize theOberth effect. The orbiter's dry mass is 500kg
(1,100lb), and it carries 852kg (1,878lb) of fuel and oxidizer. Its
main engine, which is a derivative of the system used on India's
communications satellites, uses the bipropellant
combinationmonomethyl hydrazineanddinitrogen tetroxideto achieve
the thrust necessary forescape velocityfrom Earth. It was also used
to slow down the probe for Mars orbit insertion and, subsequently,
for orbit corrections.1.10 OBJECT RAISING MANOEUVRESSeveral orbit
raising operations were conducted from theSpacecraft Control
Centre(SCC) at 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 aim was to gradually build up the
necessaryescapevelocity(11.2km/s) to break free from Earth's
gravitational pull while minimizing propellant use. The first three
of the five planned orbit raising maneuvers were completed with
nominal results, while the fourth was only partially successful.
However, a subsequent supplementary maneuvers raised the orbit to
the intended altitude aimed for in the original fourth maneuver. 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 heliocentricorbitfor its transit to Mars.The first
orbit-raising maneuver was performed on 6 November 2013 at 19:47
UTC when the 440 newtons (99lbf)liquidengine of the spacecraft was
fired for 416 seconds. With this engine firing, the
spacecraft'sapogee was raised to 28,825km, with aperigeeof 252km.
The second orbit raising maneuver was performed on 7 November 2013
at 20:48 UTC, with a burn time of 570.6 seconds resulting in an
apogee of 40,186km.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 71,636km. The fourth orbit raising
maneuvers, starting at 20:36 UTC on 10 November 2013, imparted an
incrementalvelocityof 35m/s to the spacecraft instead of the
planned 135m/s as a result of under burn by the motor.Because of
this, the apogee was boosted to 78,276km instead of the planned
100,000km.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 energized 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 118,642km,a slightly higher altitude than originally
intended in the fourth maneuver.The apogee was raised to 192,874km
on 15 November 2013, 19:57 UTC in the final orbit raising
maneuver.
Figure 1.3: Orbit Trajectory Diagram (not to scale)
1.11 TRAJECTORY CORRECTION MANEUVERSFour trajectory corrections
were originally planned, but only three were carried out.The first
trajectory correction maneuver (TCM) was carried out on 11 December
2013, 01:00 UTC, by firing the 22 newtons (4.9lbf) thrusters for a
duration of 40.5 seconds.As observed in April 2014, MOM is
following the designed trajectory so closely that the trajectory
correction maneuver planned in April 2014 was not required. The
second trajectory correction maneuver was performed on 11 June
2014, at 16:30 hrs IST by firing the spacecraft's 22 newton
thrusters for a duration of 16 seconds.The third planned trajectory
correction maneuver 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.
CHAPTER 2ISRO (INDIAN SPACE RESEARCH ORGANISATION)
2.1 INTRODUCTIONTheIndian Space Research
Organisation(ISRO,/sro/;Hindi: Bhratya Antarikha Anusandhn
Sangahan) is the primaryspace agencyofIndia. ISRO is among the
largestgovernment space agencies in the world. Its primary
objective is to advancespace technologyand use its applications for
national benefit.Established in 1969, ISRO superseded the
erstwhileIndian National Committee for Space Research (INCOSPAR).
Headquartered inBangalore, ISRO is under the administrative control
of theDepartment of Spaceof theGovernment of India.ISRO built
India's firstsatellite,Aryabhata, which was launched by theSoviet
Unionon 19 April in 1975. In 1980,Rohini became the first satellite
to be placed in orbit by an Indian-made launch vehicle,SLV-3. ISRO
subsequently developed two other rockets: thePolar Satellite Launch
Vehicle (PSLV)for launching satellites intopolar orbitsand the
Geosynchronous Satellite Launch Vehicle (GSLV)for placing
satellites intogeostationary orbits. These rockets have launched
numerouscommunications satellitesandearth observation satellites.
Satellite navigation systems likeGAGAN andIRNSShave been deployed.
In January 2014, ISRO successfully used anindigenous cryogenic
enginein a GSLV-D5 launch of the GSAT-14.On 22 October 2008, ISRO
sent its first mission to theMoon,Chandrayaan-1. On 5 November
2013, ISRO launched its Mars Orbiter Mission, which successfully
entered theMarsorbit on 24 September 2014, making India the first
nation to succeed on its maiden attempt, and ISRO thefirst Asian
space agencyto reach Mars orbit.[6]Future plans include development
ofGSLV Mk III(for launch of heavier satellites), development of
areusable launch vehicle,human spaceflight,further lunar
exploration, interplanetary probes,a satellite to study the Sun,
etc.Over the years, ISRO has also conducted a variety of operations
for both Indian and foreign clients. ISRO has several field
installations as assets, and cooperates with the international
community as a part of several bilateral and multilateral
agreements. In June 2014, it launched five foreign satellites by
the PSLV. There are plans for the development and launch of a
satellite which will be collectively used by the
eightSAARCnations.
2.2 LAUNCH VEHICLE FLEET During the 1960s and 1970s, India
initiated its own launch vehicle programme owing to geopolitical
and economic considerations. In the 1960s1970s, the country
successfully developed a sounding rockets programme, and by the
1980s, research had yielded the Satellite Launch Vehicle-3 and the
more advanced Augmented Satellite Launch Vehicle (ASLV), complete
with operational supporting infrastructure.ISRO further applied its
energies to the advancement of launch vehicle technology resulting
in the creation of PSLV and GSLV technologies.2.3 SATELLITE LAUNCH
VEHICLE (SLV)The Satellite Launch Vehicle, usually known by its
abbreviation SLV or SLV-3 was a 4-stage solid-propellant light
launcher. It was intended to reach a height of 500km and carry a
payload of 40kg.[18]Its first launch took place in 1979 with 2 more
in each subsequent year, and the final launch in 1983. Only two of
its four test flights were successful.2.3.1 AUGMENTED SATELLITE
LAUNCH VEHICLE (ASLV)The Polar Satellite Launch Vehicle, usually
known by its abbreviation PSLV, is anexpendable launch
systemdeveloped to allow India to launch its Indian Remote Sensing
(IRS) satellites intoSun synchronous orbits, a service that was,
until the advent of the PSLV, commercially viable only from Russia.
PSLV can also launch small satellites intogeostationary transfer
orbit(GTO). The reliability and versatility of the PSLV is proven
by the fact that it has launched 70 satellites / spacecraft ( 30
Indian and 40 Foreign Satellites) into a variety of orbits so
far.In April 2008, it successfully launched 10 satellites at once,
breaking a world record held by Russia.On 30 June 2014, the PSLV
flew its 25th consecutive successful launch mission,delivering a
payload of five foreign satellites into orbit. Its only failure in
26 flights was its maiden voyage in September 1993, providing the
rocket with a 96 percent success rate.2.3.2 GEOSYNCHRONOUS
SATELLITE LAUNCH VEHICLE (GSLV)The Geosynchronous Satellite Launch
Vehicle, usually known by its abbreviation GSLV, is an expendable
launch system developed to enable India to launch itsINSAT-type
satellites into geostationary orbit and to make India less
dependent on foreign rockets. At present, it is ISRO's heaviest
satellite launch vehicle and is capable of putting a total payload
of up to 5 tons to Low Earth Orbit. The vehicle is built by India
with the cryogenic engine purchased from Russia while the ISRO
develops its own engine programme.In a setback for ISRO, the
attempt to launch the GSLV, GSLV-F07 carrying GSAT-5P, failed on 25
December 2010. The initial evaluation implies that loss of control
for the strap-on boosters caused the rocket to veer from its
intended flight path, forcing a programmed detonation. Sixty-four
seconds into the first stage of flight, the rocket began to break
up due to the acute angle of attack. The body housing the 3rd
stage, the cryogenic stage, incurred structural damage, forcing the
range safety team to initiate a programmed detonation of the
rocket.On 5 January 2014, GSLV-D5 successfully launched GSAT-14
into intended orbit. This also marked first successful flight using
indigenous cryogenic engine, making India sixth country in the
world to have this technology.2.3.3 GEOSYNCHRONOUS SATELLITE LAUNCH
VEHICLE MARK-IIIThe Geosynchronous Satellite Launch Vehicle
Mark-III is a launch vehicle currently under development by the
Indian Space Research Organization. It is intended to launch heavy
satellites intogeostationary orbit, and will allow India to become
less dependent on foreign rockets for heavy lifting. The rocket,
though the technological successor to theGSLV, however is not
derived from its predecessor.A GSLV III is planned to launch on a
suborbital test flight in the third quarter of 2014/15. This
suborbital test flight will demonstrate the performance of the GSLV
Mk.3 in the atmosphere. This launch has been delayed from May,
June, July and August of 2014.2.4 EARTH OBSERVATION AND
SATELLITEIndia's first satellite, theAryabhata, was launched by
theSoviet Unionon 19 April 1975 fromKapustin Yarusing
aCosmos-3Mlaunch vehicle. This was followed by the Rohini series of
experimental satellites which were built and launched indigenously.
At present, ISRO operates a large number of earth observation
satellites.2.4.1 THE INSAT SERIESINSAT (Indian National Satellite
System) is a series of multipurpose geostationary satellites
launched by ISRO to satisfy the telecommunications, broadcasting,
meteorology and search-and-rescue needs of India. Commissioned in
1983, INSAT is the largest domestic communication system in the
Asia-Pacific Region. It is a joint venture of the Department of
Space, Department of Telecommunications,India Meteorological
Department,All India RadioandDoordarshan. The overall coordination
and management of INSAT system rests with the Secretary-level INSAT
Coordination Committee2.4.2 THE IRS SERIESIndian Remote Sensing
satellites (IRS) are a series of earth observation satellites,
built, launched and maintained by ISRO. The IRS series provides
remote sensing services to the country. The Indian Remote Sensing
Satellite system is the largest constellation of remote sensing
satellites for civilian use in operation today in the world. All
the satellites are placed in polarSun-synchronous orbitand provide
data in a variety of spatial, spectral and temporal resolutions to
enable several programmes to be undertaken relevant to national
development. The initial versions are composed of the 1 (A,B,C,D)
nomenclature. The later versions are named based on their area of
application including OceanSat, CartoSat, Resource ISRO has also
successfully launched the Indo-French satelliteSARALon 25 February
2013.12: SARAL (or "Satellite with ARgos and ALtiKa") is a
cooperative altimetry technology mission. It is being used for
monitoring the oceans surface and sea-levels. AltiKa will measure
ocean surface topography with an accuracy of 8mm, against 2.5cm on
average using current-generation altimeters, and with a spatial
resolution of 2km.In June 2014, ISRO launched French Earth
Observation Satellite SPOT-7 (mass 714kg) along withSingapore's
first nano satellite VELOX-I,Canada's satellite CAN-X5,Germany's
satellite AISAT, via the PSLV-C23 launch vehicle. It was ISRO's 4th
commercial launch
CHAPTER 3ATMOSPHERE OF MARS
3.1 INTRODUCTIONTheatmosphere ofMarsis, like that ofVenus,
composed mostly ofcarbon dioxidethough far thinner. There has been
renewed interest in its composition since the detectionof traces
ofmethanethat may indicatelifebut may also be produced by
ageochemicalprocess,volcanicorhydrothermal activity.
Figure 3.1: MARS atmosphere, visible on the horizon in this
low-orbit imageTheatmospheric pressureon the Martian surface
averages 600pascals(0.087psi), about 0.6% of Earth's mean sea level
pressure of 101.3 kilopascals (14.69psi) and only 0.0065% that
ofVenus's9.2 mega pascals (1,330psi). It ranges from a low of 30
pascals (0.0044psi) onOlympus Mons's peak to over 1,155 pascals
(0.1675psi) in the depths ofHellas Planitia. This pressure is well
below theArmstrong limitfor the unprotected human body. Mars's
atmospheric mass of 25teratonnescompares to Earth's 5148 tera
tonnes with ascale heightof about 11 kilometers (6.8mi) versus
Earth's 7 kilometers (4.3mi).The Martian atmosphere consists of
approximately 96%carbon dioxide, 2.1%argon, 1.9%nitrogen, and
traces of freeoxygen,carbon monoxide,waterandmethane, among other
gases,for a meanmolar massof 43.34 g/mol.The atmosphere is quite
dusty, giving the Martian sky a light brown or orange-red color
when seen from the surface; data from theMars Exploration
Roversindicate that suspended dust particles within the atmosphere
are roughly 1.5micro-metersacross.3.2 COMPOSITIONThe composition of
the abundant gases which are present on the mars are shown in the
figure 3.2
Figure 3.2:MARS most abundant gases
CHAPTER 4PAYLOAD
4.1 CLASSIFICATION OF SCIENTIFIC PAYLOADThe 15kg (33lb)
scientific payload consists of five instruments: Atmospheric
studies: Lyman-Alpha Photometer (LAP) aphotometerthat measures the
relative abundance ofdeuteriumandhydrogenfromLyman-alpha
emissionsin the upper atmosphere. Measuring the deuterium/hydrogen
ratio will allow an estimation of the amount of water loss toouter
space. Methane Sensor for Mars (MSM) will measuremethane in the
atmosphere of Mars, if any, and map its sources. Particle
environment studies: Mars Exospheric Neutral Composition Analyser
(MENCA) is aquadrupole mass analysercapable of analysing the
neutral composition of particles in the exosphere.4.2 EXPLANATION
OF VARIOUS INSTRUMENTS IN MARS ORBITER:4.2.1 MARS COLOUR CAMERA
(MCC)Mangalyaan carries a camera payload that acquires color images
of planet Mars. MCC covers a spectral range of 400 to 700
nanometers the visible spectrum. This tri-color Mars color camera
gives images & information about the surface features and
composition of Martian surface. They are useful to monitor the
dynamic events and weather of Mars. MCC will also be used for
probing the two satellites of Mars-Phobos & Deimos. It also
provides the context information for other science payloads
Figure 4.1: Mars color camera on-board Mangalyaan4.2.1.1
COMPONENTS OF MCC Multi element lens assembly Pixel array detector
with RBG Bayer filter4.2.1.2 MULTI-ELEMENT LENSMulti element lenses
are used when a singlet lens cannot fulfill the needed optical
function due to aberration or wave front distortion, or when more
complex optical transformation is required
Figure 4.2: Multi element lens
4.2.1.3 PIXEL ARRAY DETECTOR WITH BAYER FILTERThe PAD detector
is a 2-dimensional imager capable of storing subsequent frames in
less than 0.5 microsecond. It will be used for time resolved
experiments where speed is a critical factor
Figure 4.3: Color filter array 3D viewABayer filtermosaic is
acolor filter array(CFA) for arrangingRGBcolor filters on a square
grid of photo sensors. Its particular arrangement of color filters
is used in most single-chip digitalimage sensorsused in digital
cameras, camcorders, and scanners to create a color image. The
filter pattern is 50% green, 25% red and 25% blue.
Figure 4.4: Working of CFA
4.2.2 METHANE SENSOR FOR MARSMethane is an organic molecule
present in gaseous form in the Earths atmosphere. More than 90% of
Methane on our home planet is produced by living organisms. The
recent detection of plumes of Methane in the northern hemisphere of
Mars is of great interest because of its potential biological
origin.
Figure 4.5: Methane sensor for MARSMethane sensor for Mars is
one of the scientific instruments of the payload on MOM spacecraft,
MSM payload weighing 2.94 kg is designed to measure amount of
Methane of the order of parts per billion (ppbs) in martian
atmosphere. MSM is a differential radiometer (radiometer is a
device used to measure temperature of cosmic background) based on
Fabry Perot Etalon (FPE) filters. MSM maps the source and sinks of
Methane by scanning the full Martian disc from apogee position of
Mars Orbiter.4.2.2.1 DIFFERENTIAL MICROWAVE RADIOMETER Figure 4.6:
Differential microwave radiometer4.2.2.2 SENSOR
CONFIGURATIONFabry-perot Etalon sensor consists of two channels -
Methane channel, reference channel. Fore-optics collects radiance
from the sense and focuses it onto a field-Stop. Diverging beam
from the field stop is collimated and then divided into two parts
by a beam filter. One part of the beam transmits through FPE filter
of methane channel whereas the other part transmits through FPE
filter of reference channel and then focused onto respective focal
planes. In GaAS photo divider are used as photo detectors. In GaAs
or indium gallium arsenide is an alloy of gallium arsenide and
indium arsenide. As gallium and indium belong to Group III of the
Periodic Table, and arsenic and phosphorous belong to Group V,
these binary materials and their alloys are all III-V compound
semiconductors (In GaAS Photo detectors are sensitive to wavelength
over a wide spectral range and are available as image sensors, and
has applications in optoelectronic technology.)
Figure 4.7: Geological maps of MARS
4.2.2.2.1 FABRY-PEROT ETALON SENSOR OPTICAL CONFIGURATIONAn FPE
filter transmit optical radiation at regular intervals of
frequency. FPE filter used in methane channel and reference
channels are exactly similar. But FPE filter of reference channel
is tilted by about 1 degree with respect to the optical axis so
that its transmission peaks are slightly shifted. Transmission
bands of first Etalon exactly coincide with the absorption lines of
methane where as transmission peaks of reference Etalon are
positioned in between the gaseous absorption lines where absorption
is nil.
Figure 4.8: Functioning of fabry-perot etalon sensor
Figure 4.9: Working of FPE filter
TECHNIQUE USED TO DETERMINE CONCENTRATION OF METHANE:Radiance
measured in methane channel varies with Methane concentration in
the atmosphere where as that of reference level is insensitive to
it. So, the differential signal gives a Measure of methane in the
atmosphere. Based on this technique, Methane concentration on
Martian atmosphere is determined.
4.2.3 Lyman Alpha PhotometerLyman Alpha Photometer (LAP) is one
of the scientific instruments of the payload on MOM spacecraft,
which is Indias maiden mission to the red planet, Mars. Figure
4.10: Lyman alpha photometer
Why is it called Lyman Alpha Photometer?When electron in a
hydrogen atom makes transition from n=2 energy level to n=1 energy
level, a photon is released and this type of emission of photon is
known as Lyman Alpha emission. Photometer is an instrument for
measuring intensity of light. Lyman Alpha Photometer is an
absorption cell photometer.4.2.3.1 LYMAN ALPHA EMISSION
Figure 4.11: Lyman Alpha emission
What is an absorption cell photometer?An absorption photometer
for measuring the absorption by conducting the light to a thin flow
cell in which a liquid sample flows, wherein the sample light for
measuring the absorption peak is superimposed on the reference
light selected from the transparent(window) range of the liquid and
the absorbance is detected by separating the sample light and
reference light after transmission of the flow cell changes in the
light path conditions can be mentioned accurately and therefore
high accuracy measurement immune to noises is made possible even
using an elongated flow cell. 4.2.3.2 ABSORPTION CELL PHOTOMETERLAP
measures the relative abundance of deuterium and hydrogen from
Lyman-alpha emission in the Martian upper atmosphere .Measurement
of D/H (Deuterium to Hydrogen abundance ratio) will improve our
understanding of the process involved in the loss of water from the
planet. The estimated D/H ratio will be used in MG CM (Mars General
Circulation Model) algorithms to the present Water escape rate from
Martian Exosphere.
Figure 4.12: Absorption cell photometer a) atomic absorption
meter b) mass spectrometer.4.2.3.3 ESCAPE OF ATMOSPHERE ON MARSIn
upper atmosphere hydrogen and deuterium atoms are produced by photo
dissociation from H2O and HDO molecules. In the escape of these
atoms, the D/H ratio in the atmosphere increases with time because
escaping ratio of H atoms is expected to be greater than that of D
atoms because of the mass difference.
Figure 4.13: Escape of atmosphere on marsLAP operates on the
principle of resonant scattering and absorption at Lyman alpha
wavelengths of H and D i.e., 121.56 nm, 121.53 nm respectively.
Thermally dissociated H2 and D2 molecules in the cells absorb the
incoming H2/D2 Lyman alpha incident on the cell.4.2.3.4 TECHNICAL
SPECIFICATIONS OF LAPThe fore-optics comprising of a plano-convex
lens collects the input radiation and transmits to the gas cells.
Gas filled cells of the instrument works as an effective narrow
band-pass rejection filter at hydrogen and deuterium alpha
wavelengths. Tungstun filament is used to thermally dissociate the
gases in to atoms. There atoms will resonantly absorb the incoming
hydrogen/deuterium lyman alpha radiation at their wavelengths. A 15
nm bandwidth lyman alpha filter placed in the front of the detector
cuts-off the undesirable radiation that lies outside the wavelength
range of interest and a solar-blind side-on type photo multiplier
tube(PMT) is selected for photon detection.4.2.4 MARTIAN EXOSPHERIC
NEUTRAL COMPOSITION ANALYSERMENCA payload weighing 3.56 kg, is a
quadrupole mass spectrometer based scientific payload on MOM,
capable of measuring relative abundances of neutral constituents,
in the mass range of
Figure 4.14: Martian exospheric neutral compositionMENCA payload
weighing 3.56 kg, is a quadrupole mass spectrometer based
scientific payload on MOM, capable of measuring relative abundances
of neutral constituents, in the mass range of 1-300 amu .The core
objective of MENCA is to study the exospheric neutral density and
composition at altitudes as low as 372 kilometers above the Martian
surface. The instrument examines radial, diurnal and seasonal
variations in the Martian exosphere with Mangalyaan in its
operational orbit, MENCA is to estimate the upper limits of the
neutral density distribution and composition around mars. Studying
Martian exosphere will provide valuable data on the present
conditions.Explanation on what happens in a mass spectrometerAtoms
can be deflected by magnetic fields-provided the atom is first
turned into an ion. Electrically charged particles are affected by
a magnetic field although electrically neutral ones arent. The atom
is ionized by knocking one or more electrons off to give a positive
ion. This is true for things which you would normally expect to
form negative ions(chlorine for example) or never form ions at all(
ex: argon). The ions are accelerated so that they all have the same
kinetic energy. The ions are then deflected by a magnetic field
according to their masses. The lighter they are, the more they are
deflected. The more the ion is charged, the more it gets deflected.
The beam of ions passing through the machine is detected
electrically. . Figure 4.15: Mass spectrometer4.2.4.1 Quadrupole
rodsIt consists of four parallel metal rods with opposing rods
being connected electrically. A radio frequency voltage is applied
between the two pairs of rods and a direct current voltage is
applied between the two pairs of rods and a direct current voltage
is then superimposed on the RF voltage. Ions entering the
instrument travel down the quadrupole between the rods. Depending
on their mass-to-charge ratio, ions either enter unstable
trajectories and collide with the rods or make it through to the
detector (detectors being used in MENCA are channel electron
multiplier (CEM) and Faraday Cup (FC) Figure 4.16: Quadrupole mass
spectrometer
4.2.4.2 Electron multiplierThe m/z of ions reaching the detector
is a function of the voltage setting which allows the operator to
select an ion with a particular mass-to-charge ratio to measure its
abundance or run the instrument through a range of voltages to scan
for a number of species that might be present.Ions are generated
via electron ionization Figure 4.17: Electron multiplierElectrons
are produced through thermionic emission. The electrons are
accelerated in an electric field and focused into a beam by a trap
electrode. The atoms and molecules enter the ion source
perpendicular to the electron beam. As high-energy electrons pass
by and collide with the particles, large fluctuations in the
electric field around the neutral molecules are caused leading to
ionization and fragmentation. Figure 4.18: Working of electron
multiplierThe MENCA instrument operates at an m/z range of 1 to 300
amu (atomic mass unit) with a mass resolution of 0.5u which allows
detailed detection of species. The instrument can operate at the
low partial pressure found in the upper Martian atmosphere.4.2.4.3
Additional instruments in MENCA payloadMENCA has an in-built
pressure gauge for the measurement of total pressure. The
instrument has a provision to study the time-evolution of a set of
selectable species in the mode of operation. The primary science
goalof MENCA is the in-situ measurement of neutral composition and
distribution of the martian upper atmosphere and exosphere and to
examine its radial, diurnal and possibly seasonal variations. The
instrument has tele command, telemetry and data interface to the
space craft optical combination of operating parameters which can
be chosen through tele commands will be used to control the
instrument at different observation phases so that best possible
scientific data could be derived.4.2.5 THERMAL INFRARED IMAGING
SPECTROMETERMars is a terrestrial planet which means that its bulk
composition, like Earth consists of silicates, is metals and other
elements that typically make up rock. Also like Earth, Mars is a
differentiated planet, meaning that it has a central core made up
of metallic iron and nickel surrounded by a less dense silicate
mantle and crust. The planets distinctive red colour is due to
oxidation of iron on its surface.The knowledge on type of minerals
present in any planetary system provides the information on the
conditions under which minerals are formed and process by which
they are weathered. Much of what we know about the elemental
composition of Mars comes from orbiting spacecraft and landers.
Most of these spacecraft carry spectrometers (A spectrometer is an
instrument used to measure properties of light over a specific
portion of the electromagnetic spectrum, typically used in
spectroscopic analysis to identify materials) and other instruments
to measure the surface of mars.
Figure 4.19: Thermal Infrared Spectrometer payload on MOMThermal
Infrared Spectrometer is one of the five instruments on MOM. TIS
weighing 3.2 kg can measure the thermal emissions and can be
operated during both day and night. Temperature and emissivity are
the two basic physical parameters estimated from thermal emission
measurement. The TIS instrument measures thermal emissions from the
Martian surface to deduce surface composition and
mineralogy.4.2.5.1 Science goals of TIS To estimate ground
temperature of Mars surface. To map surface composition and
mineralogy of Mars. To detect and study the variability of
aerosol/dust in Martian atmosphere. To detect hot spots, which
indicate underground hydrothermal systems.TIS will be useful in
mapping mineral compositions and surface temperature during perigee
imaging (The perigee is the point in a satellite's elliptical path
around the earth at which it is closest to the center of the
earth)and it will be used for assessment of global temperature
distribution and aerosol turbidity in Martian atmosphere during
apogee viewing(apogee is the point in the orbit of an artificial
satellite most distant from the center of the earth).
Figure 4.20:3D Image of TISThe TIS instrument consists of a
spectrometer that features a typical infrared grating spectrometer
design. TIS consists of fore-optics, slit, collimating optics,
grating and re-imaging optics. A 120X160 element bolometer array is
placed at the focal plane of the re-imaging optics
4.2.5.2 Fiber-port lens positions for collimating Figure 4.21:
Sketch of multi wavelength re-imaging opticIn the common design,
radiation is directed through an entrance slit (available light
energy depends on light intensity of the source as well as the
dimensions of the slit and acceptance angle( acceptance angle refer
to the angle in an optical fiber below which rays are guided rays)
of the system. The slit is placed at the effective focus of a
collimator (A collimator is a device that narrows a beam of
particles or waves, which means either to cause the directions of
motion to become more aligned in a specific direction (i.e.,
collimated or parallel) or to cause the spatial cross section of
the beam to become smaller.) that directs collimated radiation
(focused at infinity) to a diffraction grating that acts as
dispersive element. Another mirror refocuses the dispersed
radiation onto a detector.TIS uses a 120 by 160 element bolometer
array detector. A bolometer is a device for measuring the power of
incident electromagnetic radiation via the heating of a material
with a temperature-dependent electrical resistance4.2.5.3 Principle
of operation of a bolometerPower P from an incident signal is
absorbed by the bolometer and heats up a thermal mass with heat
capacity C and temperature T. The thermal mass is connected to a
reservoir of constant temperature through a link with thermal
conductor.
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