Vikram Landing

Vikram is what ISRO calls the landing module of the Chandrayaan 2 spacecraft. The last we checked in on Chandrayaan 2, we witnessed the separation of the two modules of Chandrayaan 2. The orbiter module was in the correct orbit at the time of the separation.

Vikram then performed a couple of orbit lowering manoeuvre to reduce its orbit around 100 km by 30 km. As it approached the landing site, the spacecraft followed the desired trajectory through the rough braking phase where the speed of the vehicle was reduced drastically. All seemed to be going well up to this phase. The telemetry data sent back to ISRO Tracking Centre (ISTRAC) followed the mission plan.

The spacecraft then seemed to be deviating a bit from its track but seemed to be making an effort to return to the original path. The animation on the screen showed the spacecraft toppling over. It seems that Vikram was trying to stay in the correct orientation. At this point, ISRO said that they lost communication with Vikram at about 2.1 km above the lunar surface.

Doppler data from Vikram. Image: Cees Bassa, Dwingeloo Radio Telescope, Tweet.

We don’t have data as to what happened after this point. Doppler data received from Amsterdam’s Dwingeloo Radio Telescope was tweeted by Cees Bassa, an astronomer who was following Vikram at the telescope. This seems to show a “zoom” at the end which seemed to indicate a crash, according to him.

ISRO’s own telemetry screen at the last available data point seems to indicate speeds which were considered too high for a proper landing to take place at the end. The above tweet is from Jason Davis of The Planetary Society who also has a good summary of events with some international context on their blog.

I was initially unhappy that the Prime Minister Narendra Modi walked away from ISTRAC letting ISRO Chairman K Sivan do the announcement. But, today morning he came back and with data announced that communication was lost. The data is still being analysed.

There are currently two orbiters in orbit around the Moon, Chandrayaan-2’s orbiter module and NASA’s Lunar Reconnaisance Orbiter. Each should be having an orbit around 2 hours and so might come over the landing site within this month and we should be able to have a look. This would give final confirmation on what happened early today morning.

Is Chandrayaan 2 landing on the Moon’s South Pole?


Rachana, over on Twitter, asked why the CNN covered Chandrayaan 2’s Moon landing on September 7 as that of the second landing on the far side of the Moon rather than as the first polar landing by any country. Rachana is a space professional and her tweets earlier on space have been worth following. She has also written useful FAQs for students and young professionals interested in space science. At the end, I felt Rachana may have shared the tweet only with the intention of sharing the discussion on the Reddit post.

Based on this tweet, I asked Ram Ramgopal of CNN the reason for this coverage. I immediately felt lazy for not following up the question myself before asking Ram and hence went looking on Wikipedia. I recognized the error and informed Ram apologising for the complaint. I still had a few queries regarding the lunar poles that @zingaroo kindly answered. Also, if you follow the link to her tweet it goes to Reddit where Ohsin also responds to the question. I learnt that we are landing neither on the Moon’s pole nor on its far side. I am saving as reference what I learnt here.

The tilts of Earth and the Moon. Image: Peter Sobchak, Wikimedia Commons

On Earth, the polar region is defined by Earth’s tilt at 23.4 degrees. Hence, areas above the latitudes of 66.6 degrees are considered the polar region. I mapped the same onto the Moon. Here, is where @zingaroo corrected me. Moon’s tilt is only 6.68 degrees. Hence, the Moon’s polar region is only that North or South of 83.32 degrees. The Chandrayaan landing site is well outside the Moon’s poles.

As for the Moon’s far side, ISRO’s search for a landing site required the site to be on the near side of the Moon.

Chandrayaan 2 Lander Module seperation

I was away for a few days from the blog as my parents were visiting. I got news about the separation of the orbiter and lander module as I was having lunch today.

Let’s backtrack a bit, to my last update on the mission. That update was provided when the spacecraft was placed in lunar orbit. At the time, the spacecraft was one integrated unit. It is made of two components – a lunar orbiter module and a lunar lander module.

Lander (Vikram) Module and Orbiter Module of Chandrayaan 2. Image: ISRO Launch Kit

Once it reached lunar orbit, the spacecraft performed the opposite of what did in Earth orbit. In Earth orbit, it used to fire its engines at the point closest to Earth to increase its speed. Now, in lunar orbit, the spacecraft turns around and does the same to reduce its speed. As it does so, the orbit lowers and the spacecraft gets closer to orbit around the Moon.

When we met the spacecraft last, it was in lunar orbit of 114 km x 18072 km. Since then, it did four engine firings on August 21, August 28, August 30 and September 1. Yesterday’s engine firing put the spacecraft in a 119 km x 127 km orbit around the Moon.

ISRO’s tweet visualises the lander module going closer to the Moon while the orbiter module staying in lunar orbit. Image: ISRO Twitter

Today, the lander module and the orbiter module separated. Currently, both are in the same orbit. While the orbiter will continue to be in its current orbit, the lander module will eventually achieve an orbit of 110 km x 36 km. The lander module will then perform a rocket powered descent to the surface of the Moon.

You can follow the latest updates from the mission on the ISRO website. News coverage from The Wire, The Times of India (which has a 51 second video from Times Now which has animated the picture above), ThePrint (which also gives you an idea on what comes next).

Chandrayaan 2 in lunar orbit

The Chandrayaan 2 spacecraft entered into an orbit around the Moon on August 20, 2019 at 09:02 AM (IST).

This was a result of a lunar orbit insertion (LOI) manoeuvre the spacecraft performed that lasted about 1738 seconds. The spacecraft was in Earth orbit and used it’s gravity to be propelled towards the Moon. As the spacecraft reached close to the Moon it used its on-board motor to perform a breaking to decrease its speed (this was demonstrated in Mission Mangal) and allowed itself to be captured by the Moon’s gravitational force.

The spacecraft entered into a 114 km x 18,072 km orbit around the Moon. This means that the spacecraft’s closest distance from the Moon (caller perilune) is 114 km and it’s farthest distance (called the apolune) is 18,072 km. The next day it performed another similar manoeuvre to reduce its speed and moved into an 118 km x 4,412 km orbit. This is the opposite of what it did in Earth orbit and will continue till it achieves a circular orbit of 100 km.

Image from the ISRO Launch Kit for Chandrayaan 2 which shows the mission sequence.
The Chandrayaan 2 spacecraft is now in its Lunar Bound Phase. Image: ISRO Launch Kit
Moon as viewed by Chandrayaan-2 LI4 Camera on 21 August 2019 19:03 UT
Moon as viewed by Chandrayaan-2 LI4 Camera on 21 August 2019 19:03 UT

Today, ISRO released pictures taken by the LI4 camera on board the Vikram lander of the Chandrayaan 2 spacecraft. LI4 probably stands for Landing Imager 4. It should be one of the cameras on the lander that would be used to guide the lander to the surface of the Moon.

The next manoeuvre is slated for August 28, early in the morning. You can follow the updates of Chandrayaan 2 directly from the ISRO website page.


Wikipedia’s entry for Helium has these lines:

The first evidence of helium was observed on August 18, 1868, as a bright yellow line with a wavelength of 587.49 nanometers in the spectrum of the chromosphere of the Sun. The line was detected by French astronomer Jules Janssen during a total solar eclipse in Guntur, India.

Wikipedia entry for Helium

The source of the information is an article in the Journal of the British Astronomical Association by R K Kochhar in 1991 ( Kochhar, R. K. (1991). “French astronomers in India during the 17th – 19th centuries“. Journal of the British Astronomical Association101 (2): 95–100)

Portrait of Pierre Jules Cesar Janssen circa 1895
Pierre Jules Cesar Janssen, c. 1895, Wikipedia

The article is also a study of the work done in India by the French at the dawn of the field of astrophysics in the middle of the 19th century. Pierre Jules Cesar Janssen (1824 – 1907) had come to India to observe the total solar eclipse on August 18, 1868. Gustav Kirchoff’s work on using the solar spectrum to understand the chemical composition of the Sun was applied using a spectroscope.

The spectrometer separates elements of the electromagnetic spectrum and identifies elements by matching the spectrum to the wavelength of each element.

During the eclipse, Janssen was observing the solar prominence. These are gases that are blown off the Sun but still connected to the Sun’s surface. While studying these gases with a spectroscope, Janssen observed hydrogen gas but also observed light in another spectrum which did not correspond to any known element at the time. The observed spectrum was so bright, in fact, that Janssen thought that he did not have to wait for an eclipse to observe them again.

He was stationed at Guntoor from August 18 to September 4 when he observed the same spectral line each day. To continue studying the Sun on a daily basis, he built an instrument called a spectrohelioscope that he used to observe the Sun from Shimla.

His spectrohelioscope was used by other observers till 1891 when it was superseded by a spectroheliograph. Edward Frankland named this new element Helium after Helios, the Greek word for the Sun. When Janssen returned to France, he became Director of a new astrophysical observatory that the French government had built in Meudon, on the outskirts of Paris. He was President of the French Astronomical Society from 1895 to 1897.

Review: Mission Mangal (2019)

I went to PVR Cinemas at Pune’s Phoenix Marketcity Mall to watch Mission Mangal on Friday, August 15, 2019. Being a self-professed space geek, I expected the movie to be a cringe-show. It was.

Poster of Mission Mangal
Poster of Mission Mangal

Mission Mangal (2019) is a Bollywood movie inspired by the Mars Orbiter Mission (MOM). The mission involved the Indian Space Research Organisation (ISRO) flying a mission to Mars. The mission, a technology demonstrator, succeeded on it’s first attempt. The movie carries a disclaimer at the start of the movie which says that it is a fictionalised account.

The on-film depiction of ISRO is no where near it’s original. I don’t think a scientist in ISRO are insecure in their knowledge that they would feel threatened by a person who got his experience working in NASA and who returns to serve his country. This is the description of the villain of the movie. I think MOM borrowed and learnt a lot from NASA for the actual mission. MOM’s first signal acquisition was in fact from NASA’s Deep Space Network in Australia. I don’t think the movie really needed a villain.

The other issue that bothered me a lot is the need for a hero. Akshay Kumar is no where near the scientist that ISRO has. His imitation of talking to former President Abdul Kalam in Tamil was the lowest point of the film, in my opinion.

The Polar Satellite Launch Vehicle (PSLV) was made much more muscular and eye-candy than it actually is. There were a lot of holds on that American launch pad. Bollywood also made it into a two stage launch vehicle rather than the four stage rocket it is. I loved the sound and capture of the lift-off which reminded me so much of the Shuttle launches. India countsdown in minutes and seconds and not from 100 seconds.

There are struggles of the women scientist in ISRO. Tackling pressure at home, managing family, managing expectations of mother-in-laws, difficulty in getting a flat because of belonging to a certain religion and live-in-relationships. I would have been happier if these stereotypes would not all be pushed throughout the film. Also, I didn’t miss the stereotype of a woman who could not drive on road handling navigation for an interplanetary mission.

So, with all those things that I didn’t like in the movie, it still pulled through because it manages something that I think ISRO fails at communicating. How difficult it is to get funding for a mission. What parameters are considered and how difficult it is to plan a mission. It also attempted to explain orbital mechanics. The movie takes a dig at superstitious practices that ISRO itself follows. Akshay Kumar’s only positive show in the movie seems to be standing up as a rational person to some superstitious practices in the Mission Control Room.

I still think that the movie is a good starting point for a movie based on a scientific mission. For that, it is worth seeing. As I said at the beginning, I cringed a lot while watching the movie.

It took me a long time to write this review. Two other reviews are worth your time – Vasudevan Mukunth’s and Raja Sen for the Hindustan Times.

The movie ends crediting ISRO on it’s 50th anniversary and the women on whom the film is loosely based.

Chandrayaan 2 on the way to the Moon

Chandrayaan 2, India’s second mission to the Moon lifted off from Sriharikota on July 22, 2019. The spacecraft was launched on board India’s GSLV Mk-3 rocket on it’s maiden non-development flight.

Photograph of the launch of the GSLV Mk-3 with the Chandrayaan 2 spacecraft by ISRO.
GSLV Mk 3 lifts-off with Chandrayaan 2. Image Courtesy: ISRO

It came after a launch scrub surrounding which there was lack of information and a lot of speculation. I watched the launch with my grandmother in Mumbai.

Since the launch, the spacecraft which currently has an orbiter and lander attached to each other performed 5 orbit raising manoeuvres on the way to the Moon.

India adopted this gradual orbit raising manoeuvre in order to balance the limitation of the spacecraft and the launch vehicle. A lower mass of the spacecraft would enable the launch vehicle to place the spacecraft into lunar orbiter but it would then not be able to carry any meaningful payload. The launch vehicle had only enough power to place Chandrayaan 2 in a geosynchronous transfer orbit.

Image of the Earth taken by LI4 camera on board the lander on Chandrayaan 2.
Image of Earth taken by the LI 4 camera on board Chandrayaan 2. Image Courtesy: ISRO

After the 5th orbit raising manoeuvre, the spacecraft will push off towards the Moon called Trans Lunar Insertion on August 14. Afterwards, the spacecraft will perform one more burn called the Lunar Orbit Insertion on August 20 that will let the spacecraft be captured by Moon’s gravity.

Chandrayaan 1 countdown begins

This article originally appeared on my blog I recovered the post using Wayback Machine.

After what is termed as a “dress rehersal” yesterday night succeededChandrayaan-1’s countdown should have started up today morning. I think what they are referring to as a dress rehersal is going through all the steps of the launch right up to the final step without actually launching the launch vehicle (just a fancy technical name for a rocket with a payload). Things have now moved into their final phase.

Space bloggers like Emily Lakdawalla is claiming the difficulty in getting images of Chandrayaan I online. It might be difficult to see a total lack of images or information after being used to bombarded with information via websites and mailing lists. ISRO doesn’t have a good website or a good mailing list. ISRO’s Chandrayaan I website may have been well designed but it hasn’t been updated for the past 17 months. 

One of the claims that this mission was supposed to do, was to encourage excitement among the younger generation for the space sciences. This was iterated several times by the Prime Minister himself. Looking at the number of people online today, I believe that ISRO should have presented their stuff online in a much more better way than has been  done. For this historic launch too, everything has been left for the media to piece and stitch together. I believe mediapersons were given a grand tour of the launch site at Sriharikota, but nothing significant has come out of it.

There are a few people working though. Times of India’s Srinivas Laxman’s coverage (see related stories for the latest) has been outstanding, though not well timed with the launch. NDTV’s Pallava Bagla, who also co-wrote a book has some excellent coverage and a good dedicated website for India’s Moon Yatra.

In the CitizenSpace efforts to popularize Chandrayaan I launch, my friend, Raghunandan (Planetary Society, India) constant pleas for material on Chandrayaan almost fell on deaf ears. The electronic data that he now has in his hands is, in his words, “quite awesome”. He is now in transit, trying to get an unofficial glimpse of the Chandrayaan I launch. He hasn’t been able to put the content online but will be happy to forward the material to you after the launch. Catch him on his email id – planetarysocietyindia (at) gmail (dot) com. 

I am also planning to carry a series of articles on how students today can benefit from Chandrayaan I’s launch on October 22 in a series of six articles on the SEDS India blog. To sign off, the media is the best place to catch the latest action in the Chandrayaan I launch arena. I’ve tried my best to try and get some of the content online and I accept, failed but I hope the lessons I have learnt enroute will help me in future launches.

Black Hole, Beresheet and Block 5

On the eve of Yuri’s Night of 2019, a bunch of things happened around the letter B. Hence, the title of this post. All had a space connection.

B for Black Hole

Scientists from a group of scientists funded by America’s National Science Foundation released the first “image” of a black hole. The image was pieced together (this TED talk by Katie Bouman talks about how) using data collected by radio telescopes from North America, South America, Europe and Antarctica called the Event Horizon Telescope. Vasudevan Mukunth provided a nice background before the announcement on The Wire.

Scientists have obtained the first image of a black hole, using Event Horizon Telescope observations of the center of the galaxy M87. The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. This long-sought image provides the strongest evidence to date for the existence of supermassive black holes and opens a new window onto the study of black holes, their event horizons, and gravity. Credit: Event Horizon Telescope Collaboration

I followed the announcement itself on Twitter. There was also a lot of attention directed at Katie Bouman for her work highlighted in her 2016 TED talk linked above but she was at pains to repeatedly call it the work of her team which is laudable. The South Indian comparison to a medu wada was inevitable I guess. That formed the best tweet during the afterglow of the announcement on Twitter.

Tweet by @NirujMohan comparing the medu vada with the black hole image.

XKCD also has a lovely cartoon giving a comparison of the imaged M87 galaxy to the size of our solar system that I found a wonderful tool to get the scale of the image. Sandhya Ramesh writing for The Print has a nice rundown of all the stuff shared during the press conference and the 6 papers published for the result.

XKCD giving a size comparison between the size of our solar system and M87. XKCD notes that perhaps Voyager 1 has just passed the event horizon. Image Credit: XKCD, Randall Munroe.

B for Beresheet

A private spacecraft built by SpaceIL had its landing scheduled for April 12 Indian time. SpaceIL was a competitor in the Google Lunar X Prize. However, despite the fact that they could not meet the deadline for the Prize, they went ahead and launched their spacecraft to aim to become the first private spacecraft to soft land on the Moon but ended up becoming the first private spacecraft to hard land on the Moon. A malfunction in the lander’s main engine led to it crashing into the Moon at almost 500 km/hr from a height of 150 meters. So near and yet so far…

Team Indus was also on it’s way to the Moon being the Indian entry to the Google Lunar X Prize but ISRO cancelled its contract for launching it on the PSLV. They are now trying to revive the launch and perhaps a nice stimulus is the opening of the chance of becoming the first private spacecraft to soft-land on the Moon. ISRO’s own Chandrayaan-2 is on an ever delaying attempt to launch to the Moon with the latest date being being the second half of 2019.

B is for Block 5

I cheated a little here to get the B’s in a string. But, this refers to the Block 5 of the Falcon Heavy which took off with a 6 ton Arabsat-6A. The launch was of a Falcon Heavy with an Ariane-V like configuration with one core first stage with two strap-on boosters.

The focus of the mission seems to have been the launch itself. It is the world’s most powerful rocket. Also, the sights of the twin boosters landing seems to have eclipsed the whole mission. No one is even asking about Arabsat!

I couldn’t catch the Falcon Heavy launch live but saw it while having breakfast in the morning on the next day. What a lovely day for space!

India conducts an Anti Satellite Missile Test

This article was originally posted here

Pictures released of the Anti Satellite Missile Test conducted by India on March 27, 2019. Image Credit: Shiv Aroor/LiveFist

Indian Prime Minister Narendra Modi announced today that India had successfully carried out an Anti Satellite Missile Test (ASAT). The mission was code named Mission Shakti. A missile was launched from the Dr. Abdul Kalam Island Launch Complex off the coast of Orissa and hit an Indian satellite orbiting at 300 km. The hit was successful.

It is to be said that this is an important technology demonstration on the part of the Defence Research and Development Organisation (DRDO). It is a capability that only three other countries in the world have – USA, Russia and China. Of these, China seems to be the reason that India accelerated the development of the ASAT. China did the ASAT test in January 2007 by destroying a satellite in a 800 km orbit. The US responded to this with tests of its own in 2010 by destroying a satellite in a 300 km orbit.

India’s response was a Ballistic Missile Defence (BMD) test it performed in 2012 where an incoming missile was intercepted by an interceptor missile. DRDO which had developed the said capability said that it had the building blocks to test the ASAT by 2014. However, it is believed that then UPA Government under Dr. Manmohan Singh did not give the DRDO the go-ahead for this project. It is believed that India feared further restrictions on technology transfer from the US as the basis for not giving the project the go-ahead. It is believed that the go-ahead came after the Narendra Modi government when it came into power in 2014.

It is essential to seperate the civilian and defence space programmes. India did this in 2008 in response to the India-US Civilian Nuclear Deal. Although ISRO launches defence satellites into orbit, it does not intend the end purpose of such a mission be purely military. DRDO developed and launched the target satellite and launched it on a PSLV-C44 this year in January.

With this test, India has a slight advantage over China. Although, China has a ASAT capability it is widely believed that it does not have the capability yet to destroy incoming missiles provided by a BMD programme.

In today’s test India seems to have pranced around all the international treaties that look to prevent the weaponization of space. The concept took root in a 1969 treaty called the Outer Space Treaty. The Treaty is today called outdated and there are several loopholes that many countries today take advantage of like China did in 2007 and India did today. The US has been working to ban anti-satellite tests since 2010 but has failed in building any consensus on the subject. India seems to have conducted the test to ensure that it slips through the door before it closes, metaphorically.

There is a lot of political discussion on whether the timing of the announcement of the mission by the Prime Minister today is a violation of the Model Code of Conduct which is in force for the 2019 National Elections. But, that is for the Election Commission to look at. I do not see any need to do this so urgently unless the anti-satellite test ban were to come into force some time in the near future and India had an inkling as to the timing of the same. The simplest explanation is that the mission was ready and the go-ahead was given by the Government thinking of it as a matter of national defence and prioritised the decision over the Elections.

There is also worry of the creation of space debris which would be left behind by the satellite that was destroyed by the missile today. However, they have the US example of 2010 which also destroyed a satellite in a similar orbit and which lasted in orbit for about 3 years. Against this, stands the Chinese example whose destroyed satellite in the 800 km orbit is still believed to be in orbit. We are given to understand that the debris would eventually get pulled down by Earth’s gravity and will burn up in the Earth’s atmosphere before causing any significant damage. This matter is debatable.

All in all, given the timeline and the current available knowledge, India responsibly tested its capability keeping multiple issues in mind – space debris, Outer Space Treaty and current regional geopolitics.

More reading

The Ministry of External Affairs posted a Frequently Asked Questions section on its website on today’s test. Curiosly, this is not on the Ministry of Defence or the DRDO website. It has useful information and the official version of what transpired.

LiveFist – Shiv Aroor is a defence journalist who maintains a defence blog. His writeups cover most of the technical details and the defence organisational intrigue that was involved in today’s mission. The post linked here also has multiple links that are worth following up on if you’re interested in more details of the ASAT.

There is a 2012 India Today article being circulated on Twitter claiming that India had build capability required for today’s test in 2012 itself. There is significant difference between capability and technology demonstration. And, I believe it’s always a good idea to test a technology before use, if you can.

Vasudevan Mukunth wrote in The Wire about the Mission Shakti, which also analyses the technicalities of the Mission in detail which is also a good overview if you only want to understand what this whole hoopla is about.