From 3D mapping to finding water molecules, and from checking out minerals to landing where nobody has landed, scientists say ISRO has prepared to land a “dream on the Moon”.
CHALLENGES OF THE MOON LANDING
1.Trajectory Accuracy
Distance to Moon is 3,844-lakh-km. Ensuring trajectory accuracy is key. It’s influenced by Moon’s gravity—different parts have different pulls. Other astronomical bodies & solar radiation pressures also influence.
2.Deep-space Communication
Owing to distance and limited on-board power, there’ll be a communication delay. Every message sent will reach after a few minutes. Signals become weak with back- ground noise which must be picked up by antennas.
3. Trans Lunar Injection & Lunar Capture
Mission will have a series of engine burns to get close to Moon whose location changes continuously. Intersection of spacecraft & Moon’s path must be predicted in advance with accuracy. Margin of error is narrow.
4. Orbiting Around Moon
Lunar gravity is ‘lumpy’ due to uneven mass distribu- tion & influences spacecraft’s orbit. Precise knowledge of temperatures 100km away from Moon is key.
5. Soft Landing on Moon
Variation in local gravity must be factored into lunar descent trajectory. All systems have to work in unison & landing site landscape features shouldn’t result ina com- munication shadow area.
6. Lunar Dust
Firing on-board engines close to surface results in backward flow of hot gases & dust. Lunar dust is miniscule & hard. Its negative charge makes it stick to surfaces and can cause a disruption in deployment mechanisms, solar panel performance and so on.
7. Extreme Temperatures & Vacuum
A lunar day or night lasts 14 Earth days. This results in extreme surface temperature variations. Ambient pressure of surface is a hard vacuum which makes it a hostile environment for lander & rover.
Payloads which will help study the moon
1.Terrain Mapping Camera-2 (TMC- 2):
Prepares detailed 3D map
2.Collimated Large Array Soft X-ray Spectrometer (CLASS):
Maps abundance of major rock forming elements
3.Solar X-ray Monitor (XSM):
Observes X-rays emitted from Sun & supports CLASS
4.Orbiter High Resolution Camera (OHRC):
Provides high-resolution images of landing site
5.Imaging Infra-Red Spectrometer (IIRS):
Identifies minerals & signatures of hydroxyl and water molecules
6.Synthetic Aperture Radar (SAR):
Maps lunar craters & other features especially in polar regions
7.Chandra’s Atmospheric Com- position Explorer (CHACE-2):
Will carry out a detailed study of lunar exosphere
8. Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA): Measures total electron content (TEC)
9.RAMBHA (Langmuir Probe):
Measures TEC of lunar ionosphere & its morphology. Measures surface plasma density & changes
10.Chandra’s Surface Thermophysical Experiment (ChaSTE):
Measures thermal prop- erties of regolith & polar region
11.Instrument for Lunar Seismic Activity (ILSA):
Measures seismicity around landing site & structure of crust & mantle
12.Laser-Induced Breakdown Spectroscope (LIBS):
Derives chemical composition & infers min- eralogical composition on surface
13.Alpha Particle X-Ray Spectrom- eter (APXS):
Determines elemental composition of rocks and soil
Apart from these 13 scientific instruments, the mission will carry a passive payload, Retroreflector, from NASA.