Vikram: India to the Moon

Indian Chandrayaan/Vikram lunar landerYou may recall that back on 2019-04-11 we covered the attempt by Israeli non-profit company SpaceIL to land its Beresheet spacecraft on the Moon.  The landing occurred, but with an impact velocity much greater than the hoped-for soft touchdown, dashing Israel’s hope to be fourth country to soft land on the Moon and, incidentally, thwarting plans for the tardigrade conquest of Earth’s natural satellite.

Now, it’s India’s turn.  Today, on 2019-09-06, India’s Vikram lander is scheduled to attempt a soft landing on the Moon between craters Manzinus C and Simpelius N near 70.9° south latitude, the southernmost point of any Moon landing.  The lander is part of the Chandrayaan-2 mission, which was launched on 2019-07-22 by the Indian Space Research Organisation from the Satish Dhawan Space Centre.  If the landing is successful, the lander will deliver a solar-powered rover, Pragyan, to the surface.  The main Chandrayaan spacecraft will study the Moon from a high-inclination 100 km orbit; it released the lander on Monday at 07:45 UTC.

Landing is scheduled for 20:23 UTC.  Live coverage will begin at 19:40 UTC.  A UTC clock appears in the top right of this page.  Embedding of the live coverage is not permitted; you can watch it on YouTube.

Additional details about the mission are posted on Spaceflight Now.

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

23 thoughts on “Vikram: India to the Moon”

  1. ctlaw:
    Youtube is attempting to caption the Hindi as English gibberish.

    Hmm….  It doesn’t show me captions or a captioning option.  This is watching the Web player from Chrome.

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  2. John Walker:

    ctlaw:
    Youtube is attempting to caption the Hindi as English gibberish.

    Hmm….  It doesn’t show me captions or a captioning option.  This is watching the Web player from Chrome.

    Watching on space.com

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  3. John Walker:

    ctlaw:
    Youtube is attempting to caption the Hindi as English gibberish.

    Hmm….  It doesn’t show me captions or a captioning option.  This is watching the Web player from Chrome.

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  4. Not a terribly good job of public affairs communication, at least in English.  You’d expect a statement like “We lost telemetry at XX:XX.  Waiting to see if communications can be re-established.”

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  5. ctlaw:
    A pretty bad lunar record for countries beginning in “I”.

    Yeah, if Iran gets around to trying it, maybe they’ll change their name back to “Persia” for the event.

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  6. Why is it so hard to land since I think landing on earth by drones is fairly routine now? Engine failure? Terrain? Curry in the electronics? Chinese parts?

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  7. 10 Cents:
    Why is it so hard to land since I think landing on earth by drones is fairly routine now?

    It’s hard because there are lots of things you can’t completely simulate and test until you actually try doing it for the first time.  You have engines which have to operate after months of exposure to vacuum and the hot/cold cycle of deep space, a landing radar which has to perform in an environment with terrain unlike any on Earth, possible interference with star and Sun sensors due to light from the Moon, electronics subjected to upsets from solar and galactic cosmic rays which do not occur on Earth or in low Earth orbit, and a system which has to operate completely autonomously due to speed of light lag between the Earth and Moon.  Whatever happened here appears to have occurred when the lander was transitioning to its throttleable fine braking and landing thrusters.  As I understand the design, this would have been the first time they were used in the mission.  As a wild guess, that’s where I’d start looking for the problem.  We’ll have to wait for analysis of telemetry for an answer to what actually happened.

    Space is hard.  After an almost flawless first flight on Apollo 4, Apollo 6, the second flight of the Saturn V, experienced multiple failures which almost led to catastrophe, most due to causes which could not be discovered by ground testing.

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  8. 10 Cents:
    99.99999% successful. 🙂

    Let’s work it out.  Delta-v from Earth’s surface to the lunar surface is around 15,000 metres per second (there are a lot of details glossed over here, but I’m doing a Fermi calculation).  When you arrive at the lunar surface, you want to reach an altitude of 0 metres at a velocity of 0 metres/second.  The last telemetry I saw from Vikram had it descending around 50 metres/second.  So, if the precise delta-v we need to touch down softly on the Moon is 15000 m/sec and they achieved 14950, then they were 99.67% successful.

    Missed it by that much.

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  9. John Walker:

    10 Cents:
    99.99999% successful. 🙂

    Let’s work it out.  Delta-v from Earth’s surface to the lunar surface is around 15,000 metres per second (there are a lot of details glossed over here, but I’m doing a Fermi calculation).  When you arrive at the lunar surface, you want to reach an altitude of 0 metres at a velocity of 0 metres/second.  The last telemetry I saw from Vikram had it descending around 50 metres/second.  So, if the precise delta-v we need to touch down softly on the Moon is 15000 m/sec and they achieved 14950, then they were 99.67% successful.

    Missed it by that much.

    I was calculating how many miles safely flown. 🙂

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  10. 10 Cents:
    I was calculating how many miles safely flown.

    You don’t care about distance in space—it’s all about velocity.  If you’re trying to, say, hit a target and you’re off by a fraction of a centimetre per second on your trajectory, you can end up a hundred million kilometres from the target.  Conversely, if you arrive precisely at the target at the correct time, but you’re going 1 kilometre/second rather than 1 metre/second (which is what happened to Beresheet), it’s a really bad day for the Tardigrade Invasion Force on board.

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  11. John Walker:

    10 Cents:
    I was calculating how many miles safely flown.

    You don’t care about distance in space—it’s all about velocity.  If you’re trying to, say, hit a target and you’re off by a fraction of a centimetre per second on your trajectory, you can end up a hundred million kilometres from the target.  Conversely, if you arrive precisely at the target at the correct time, but you’re going 1 kilometre/second rather than 1 metre/second (which is what happened to Beresheet), it’s a really bad day for the Tardigrade Invasion Force on board.

    You sound like an engineer. A salesman would see the data differently.

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  12. 10 Cents:
    You sound like an engineer. A salesman would see the data differently.

    Engineers are often stuck implementing a saleman’s lame idea.  Or impossible idea.  There’s little love lost between engineers and salesmen.   With the possible exception of engineers who are their own salesman.  (:

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  13. Phil Turmel:

    10 Cents:
    You sound like an engineer. A salesman would see the data differently.

    Engineers are often stuck implementing a saleman’s lame idea.  Or impossible idea.  There’s little love lost between engineers and salesmen.   With the possible exception of engineers who are their own salesman.  (:

    Engineers never want to break the laws of physics. Go figure!

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  14. Here is Scott Manley’s analysis of the crash, combining images from the ISRO control centre with plots from the Dwingeloo radio telescope in the Netherlands which eavesdropped on the telemetry signal from the lander and produced a Doppler plot showing its velocity as the landing attempt progressed.

    There is a distinct kink in the velocity plot just at the moment the trajectory started deviating from the predicted path.  This appears consistent with the spacecraft tumbling at this point.

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