Chandrayaan II to the Moon : Here is a brief run-through

“Moonlight drowns out all but the brightest stars.”
― J.R.R. Tolkien, The Lord of the Rings

The Moon – a muse to a poet/artist; a friend in the sky to someone; a silent reminder about the existence of seasons of both waning and waxing to another; a source of hope to me and you.

Also, the Moon – a potential site for space civilization, water, natural resources, minerals, specially helium-3 and the much coveted knowledge about formation and evolution of  our universe.

Earth Rise as seen from surface of the Moon (Taken 1968, Recreated) (Source: NASA)

Hold up! In the first place, why explore ‘the moon’, why not Mars or Venus?

Because it is the closest celestial body to our Mother Earth; i.e. at its orbital aposelene (aka apogee), the Moon is roughly at 230,000 miles (370,000 km). Getting to know more about the Moon which has been geologically inactive for ages now, is our best bet in discerning and understanding the origins of the universe; also our first prep step in boldly going to where no man has ever gone before. Also, we are possibly looking at the establishment of a trillion dollar industry (nuclear clean energy using Helium-3) if the objective of the Chandrayaan-II mission is achieved.

(Besides, having grown up listening to Indian mealtime stories, I strongly believe that there is a really nice grandma making meduvadai on the Moon and I really wanna try it! If you are a #Thamizhanda, you sure do know what am referring to. If not, just ignore my rambling and read on!)

Talking about India’s first ever lunar probe, Chandrayaan-I, it sure was a grand success. Launched into space using India’s workhorse PSLV alongside 10 other domestic and international payloads (talk about efficiency!) and after 17 days of journey – exploiting the gravitational forces (we call it the trans-lunar injection and the whole process is very interesting, see figure below), the Moon mapping probe reached its destination. Stationed in the mapping orbit at 62 miles (100 km) from the moon surface, the Chandrayaan-I collected scientific information to prepare a 3-D Atlas (like a hologram) using a Terrain Mapping Camera and Hyper Spectral Imager (just fancy versions of cameras). The terrain maps of the North Pole and South Pole, along with the third largest crater Clavius are released to the public and the complete data is still being analysed extensively. Take an in-depth look at the moon surface and delve in Selenology in ISRO’s Science Data Archive, here and download the latest Moon Atlas too. In addition to the spectrometers and imagers, there was also a Moon Impact Probe (MIP) which was released and successfully made to hit the surface on Nov 14, 2008 (On Chacha Nehru’s birthday! He pioneered the mission~).

Chandrayaan LTI
Lift-off of PSLV C11 & the Trans-lunar injection trajectory of Chandrayaan-I (Source: ISRO)

By analyzing the wavelength of light reflected from the moon surface (*drum roll* here), the Chandrayaan-I (in colloboration with NASA JPL – Moon Mineralogy Mapper M3) took away the honor of being the first to discover the presence of water (or hydroxyl) on Moon & gave India an afterburner boost in the race to space!

Enough about the past achievements, moving on to the upcoming India’s triple kill (Orbiter, Lander & Rover) mission, the Chandrayaan II is expected to be launched NET (No Earlier Than) October 2018. This mission will elucidate to the space industry that ISRO has the technology dexterity “to soft land on other heavenly bodies”, in the words of Dr. K Sivan, chariman of ISRO.

The Chandrayaan-2 which has a launch mass of 7253 lbs (3290 kg), twice heavier than its predecessor – will be launched into orbit using the ISRO’s GSLV Mk II (Geosynchronous Launch Vehicle) with an indigenous cryogenic engine (CE-7.5).

Lets say you are on board the Chandrayaan-2, how will you land on the Moon?

Chandrayaan-II Mission Profile (Source: ISRO)
  • First of all depending on the launch date and the position of the moon, orbit calculations have to be done. We know the Moon is in an elliptical orbit around our Earth. We follow what is termed as the Hohmann transfer to reach Moon’s orbit. Start with a smaller elliptical orbit around the Earth, gradually elongate the ellipse until your orbit intersects that of the Moon’s. Then, gradually shorten the ellipse, and land on Moon. Simple right? Lets see it in detail.
  • First you will have to get to the elliptical Earth Parking Orbit (EPO). The apsis (extreme points) of the orbit are written as perigee (closest point to focus) x apogee (farthest point). So the EPO that you will be going to has already been determined to be 180 km x 24000 km. It is a temporary orbit where the Mission Control center will check Chandrayaan-II’s various control systems (instrumentation, communication etc..) and give the go/  no-go command. So, launch from Sriharikota, India on the GSLV-F10 and hold on tight!
  • The four liquid strap-on boosters (L-40) will be ignited first and after 4.6 seconds, the first stage which is a solid propellant core stage (S-125) will also be ignited which will result in you lifting-off the launch pad. The S-125 will burn for about 100 seconds taking you to an altitude of 73 km, detaches and drops down to the Indian ocean. (They are not going to be recovered!) About 1.6 seconds before the staging (the separation process), the second stage will be ignited. The second stage is comprised of aVikas engine, burning for 150 seconds and taking you to an altitude of 127 km above the Earth’s surface. The third stage which is the cryogenic CE-7.5 then ignites and burns for 710 seconds. This will make sure that the spacecraft reaches a velocity of 10.2 km/s (a little short of Earth’s escape velocity 11.2 km/s, because we don’t want you to escape Earth at all!) and taking you to the parking orbit at an altitude of 195 km and separates from the spacecraft. Note that the altitude of the EPO is actually subjected to change depending on the launch date. Now the Mission Control is going to test all the systems and give you a go. Until then, grab some snack and enjoy the magnificent Earth view!
  • Once you have the go signal, it is time to elongate the elliptical orbit that we are in. We call them Earth Bound Maneuvers (EBN -Don’t ask me why ‘N’ and not ‘M’, because people decide on things differently sometimes!!!) India’s low thrust liquid engine, the 440 Newon Liquid Apogee Motor (LAM) will be used for the orbital maneuvers. You fire your engine every time you are at the perigee to increase your apogee (~386,000 km) to a Lunar Transfer Trajectory (LTT) and then do one another engine firing for course correction to put yourself in an orbit that exactly intersects the Moon’s orbit (approximately at an apogee of 380,000 km).
  • Now that you are in an elliptical Moon’s orbit, you can start your Lunar Bound Maneuvers (LBNs) to reach a circular parking orbit (100 km x 100 km) around the Moon. You can achieve this by firing the engine for whenever you are at the apogee, and gradually reducing your apogee distance. Remember that this entire journey to reach the Moon Parking Orbit (MPO) is going to take about a month. (You will get your food through tubes, so DON’T PANIC!)
  • The orbiter will be carrying five instruments – Spectrometers, Radar and a Terrain Mapping Camera. Three of them are brand new and the other two are upgraded versions of the ones used by Chandrayaan-I. This is to quench the thirst of scientists, literally and figuratively by attempting to determine exactly how much water/hydroxyl is available on Moon and look for more minerals. Chandrayaan-I mapped 45% of the Moon, so now the rest 55% will be taken care of to provide a full 3-D atlas.
  • But you are not going to keep orbiting! The Landing site has already been chosen based on data collected. Though tricky, the rover has to be landed on a high plain near the South Pole at 70o latitude, between two craters Manzinus C and Simpelius N. Take a look at your landing site in the figure below. Some missions use parachute to soft-land, but your landing technique will be utilizing real-time active feedback from the surface using cameras and adjusting thrust & vector accordingly. Fear not! The lander is going to be fully equipped ‘with eyes and ears’ by ISRO’s Space Application Center (SAC) – a Orbiter High Resolution Camera (OHRC), Ka-band Altimeter, Lander Position Detection Camera (LPDC) and Lander Hazard Detection and Avoidance Cameras (LHDAC) and four 800 N (180 lbf) throttle-able liquid main engines and attitude thrusters with all the required software, designed to withstand extreme temperatures (minus 30o C to 70o C ) too.
Chosen landing site for Chandrayaan-2 (Sources: Ivanov et al., ISRO)
  • Soft-landing is going to be the most challenging part of the mission. First, separate yourself from the orbiter. Fire the engine and change your orbit to have a 18 km periselene (aka perigee). Reach the periselene, apply brakes (accelerate in the opposite direction), use the cameras & lander engine and with a controlled descent, the lander will have to be lowered. Though the lander legs will be equipped to absorb the shock, it has to be done with care!
  • Whew, now that you landed, exit the lander on your six-wheeled aluminium rover equipped with a stereoscopic 3-D camera, kinematic traction control and motor dynamic provided by IIT Kanpur.  So what you waiting for? Take your rover and go for a drive on the moon!!! But be warned, the speed of the rover is 2 cm/s. (So you better put together a great playlist, LOL!)

The solar-powered rover has a two-week mission of collecting lunar surface elemental composition data and sending it to the lander which will relay it to Earth. The lander has its own data collection mission – Langmuir probe to measure the moon’s plasma (aka ‘moon dust’), there is some confusing science (with added fiction) behind it. It has to be measured because it is harmful to humans. Period. There is also a seismometer to record moonquakes and instruments to measure temperatures below the soil. This is the first step in planning for moon colonization.

Coming back to the rover, though media has been publicizing that the major intent of India’s quest to the Moon is to mine for Helium-3 (which comes from one news source, the article by Anurag Kotoky via Bloomberg Quint) quoting Dr. K Sivan, “The countries which have the capacity to bring that source from the moon to Earth will dictate the process, I don’t want to be just a part of them, I want to lead them.” Like I said, it is just one statement being reiterated everywhere else and the purpose of the mission is technology demonstration and looking for water!

Lets forget the auxiliary stuff and stick to science. What is Helium-3 and why is it precious (5 billion dollars a ton) ?

With growing population, our energy need is also multiplying. Nuclear fission (breaking apart a large nucleus into two smaller ones) and fusion (fusing two lighter nuclei to form a heavier nucleus) are feasible alternatives (though not renewable) to leeching away Earth’s resources. Nuclear fission reactors have been in use since 1954, with 451 currently in operation and 58 under construction. But fission reaction is dangerous because it generates radioactive waste and can get out of control sometimes – Chernobyl, Fukushima & Three Mile island to name a few. Fusion is much safer and we know that it has powered the Sun since forever. Scientists have been trying to generate power through fusion over the past 5 decades with little progress. In southern France, an international collaborative project with 7 countries (ITER) is currently under construction to build the fission reactor.

Again, why Helium-3?

Not going into chemistry and equations, the problem is that fusing the nuclei requires a lot of  energy. Simply put, we spend energy to fuse them together and when fusion occurs, they release a tremendous amount of energy, much higher than what we spent. During the multiple processes that we do (confinement, heating, power generation etc., read in detail here), Helium-3 or Hydrogen-3 has to be generated in the laboratory which requires very high temperatures (and a lot of money!). Having Helium-3 readily available will save us that trouble~ That is why mining the moon for He-3 is considered lucrative. Unlike Earth, Moon doesn’t have magnetic field and atmosphere surrounding it to deflect the solar winds, so currently it has been roughly estimated that about 1,110,000 metric tons of He-3 has been dumped on the lunar surface. As proposed by the Artemis Project, one trip to Moon and filling up the space shuttle cargo bay with 25 tonnes of Helium-3 and bringing it back to Earth will power USA for a year! 

Alright, what is the current status? (Source: ISRO)

  • Orbiter, Lander, Rover fabrication and integration of control systems & instruments, structural integrity tests – Completed
  • Open field test to ensure Lander-Rover Integration – Completed
  • Lander legs drop test for shock absorption (Lander Actuator Performance Test LAPT) – Complete
  • Rover mobility test with simulated lunar surface with craters & plains – Completed
  • 800 N Liquid Engine sea-level test – Completed
  • Creating material that 99.6% matches the lunar soil, anemic gravity replication and testing the rover on it – Completed
  • Upgrading GSLV MK-II for the GSLV-F10 mission – No Update
  • Validation of necessary software and realization of engines – Delayed
  • “The experts had met recently and suggested the tests, following which the mission will now be launched in October” – Dr. K. Sivan
  • Current estimated total mission cost: $123 million(Note that Interstellar’s budget was $165 million) – The cost of launching from India is about half of what it would be if launched from other countries. This has been made possible through simplifying the system and strict quality control practices.
  • Why postponed to October? – Dr. K Sivan explained, “Unlike, other satellite launches where ISRO could easily defer the launch by a day or two to get a perfect mission, ISRO can’t do the same in this mission. This is because the ideal date for the moon launch comes only once in a month. If we skip that date of the month, we have to plan the launch next month.” It is to utilize the solar-powered rover for the full 14 days of mission by avoiding eclipses.
  • It was going to be a Indo-Russian project, but the Russian connection was severed in 2011 (because of Fobos-Grunt failure) causing all the unprecedented delays, but we are getting closer to the launch.
Rover, Orbiter, Lander and Integration (Clockwise) of Chandrayaan-2 (Source: ISRO)

In conclusion, it all comes down to H2O – In the words of Dr. Vanitha Muthayya,  Chandrayaan-2’s project director at ISRO“Locating substantial water could pave the way for the future habitation of the moon,” as water is a limiting factor for operating a base.” Also, Venugopal, the Senior Scientist and Project Lead at ISRO candidly said,

“It may sound crazy today, But you’ll see that one day men will be working out of there, and the goal is to launch interplanetary satellites from the Moon”

So going to the Moon as a common man/woman (and not a trained astronaut) is not very far in the future!

Well, Who knows? We might be sipping some nice cardamom chai (with vada) on the Moon just in our own lifetime~ Cheers!

Signing off with my favorite author Paulo Coelho’s quote,

“Go further than you planned. Ask for the Moon: you will be surprised how often you get it”


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