LRO to attempt imaging of Chandrayaan-2 Vikram next this week

Discussion in 'The Watering Hole' started by Marc_G, Sep 15, 2019.

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  1. Sep 15, 2019 #1

    Marc_G

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    Since we haven't seen any camera images from the Indian satellite orbiting the moon, we've all been wondering what's to be seen. the Lunar Reconnaissance Orbiter will be in position to take shots of the area this coming week:

    https://bgr.com/2019/09/14/india-moon-crash-nasa-lro-lander/

    Such a bummer that it failed, but it will be interesting what can be learned from images.
     
  2. Sep 15, 2019 #2

    Winston

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    Last week I emailed the listed NASA contact on one of the NASA LRO web pages asking when the LRO was expected to pass over it. No response...

    From a link given at your link:

    "NASA’s Lunar Reconnaissance Orbiter will try to locate India’s Vikram lander on the moon during a flyover of the landing site Tuesday. Indian space officials said they found the disabled spacecraft on the moon using the country’s own Chandrayaan 2 orbiter, but declined to release any images."

    "but declined to release any images" WHY?!

    All that accomplishes is to make one suspect that there are problems with it, too!
     
  3. Sep 15, 2019 #3

    dhbarr

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    Maybe, like with Beresheet, they want a chance to analyze the data with their international partners and disseminate conclusions before going to press?
     
  4. Sep 15, 2019 #4

    Winston

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    Then they should STATE that. Also, so what if public conjecture is incorrect? They can later make an official statement correcting it. Also, will they ask the LRO team to not release the image for the same reason?

    Sorry, for anything other than COMMERCIAL competitive reasons like when SpaceX plays mission failure images and videos close to its chest, anything other than full sunlight is inexcusable. The Chinese are somewhat secretive because their space missions are closely associated with their military despite attempts to make it not look so. Could it be the same here? Secrecy, even unnecessary levels of secrecy is a habit of militaries.
     
  5. Sep 17, 2019 #5

    Sooner Boomer

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    The Orbiter High Resolution Camera (OHRC), is capable of 30 centimeters per pixel resolution, slightly edging out NASA’s Lunar Reconnaissance Orbiter in terms of its ability to resolve surface details. Apparently, the orbiter has located the lander.

    "It had a hard-landing very close to the planned (touch-down) site as per the images sent by the on-board camera of the orbiter. The lander is there as a single piece, not broken into pieces. It's in a tilted position," an Isro official associated with the mission claimed on Monday.

    more: https://timesofindia.indiatimes.com...k-with-lander-vikram/articleshow/71045854.cms
     
  6. Sep 17, 2019 #6

    NAR29996

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    The sun will be very close to the horizon on this attempt, so I don't know if they'll be able to see much with the long shadows.
     
  7. Sep 17, 2019 #7

    Winston

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    Surface resolution depends upon altitude and the stated resolution of the LRO's camera was apparently from it's original orbit, not it's much lower pass altitude over the lunar south pole in its current orbit as I pointed out in the other thread on this. It will be interesting to see what the NASA LRO sees. In other statements they claim that it is within 500 meters of its intended landing spot. Their statements still don't match the value of pictures which are "worth a thousand words."
     
  8. Sep 17, 2019 #8

    Winston

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    Long shadows are what you want UNLESS one hides the lander.

    LRO images of Apollo 12 site and Surveyor 3 with sun angle slider:

    http://www.lroc.asu.edu/featured_sites/view_site/19
     
    Last edited: Sep 17, 2019
  9. Sep 18, 2019 #9

    Winston

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    NASA Moon Orbiter Fails to Spot India’s Lunar Lander: Report

    https://www.space.com/lro-fails-see-india-moon-lander-vikram.html

    LRO’s Lunar Reconnaissance Orbiter Camera instrument, or LROC, imaged the intended south pole touchdown site for the lander, which is called Vikram, as planned yesterday (Sept. 17), Aviation Week's Mark Carreau reported. But "long shadows in the area may be obscuring the silent lunar explorer," Carreau wrote.

    “It was near dusk as the region prepares to transition from a two-week lunar day to an equally long lunar night, so shadows covered much of the region, and Vikram may not be in the LROC’s field of view," Carreau wrote, citing a NASA statement. (The Aviation Week article is behind a paywall.)
     
  10. Sep 18, 2019 #10

    Winston

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  11. Sep 19, 2019 #11

    georgegassaway

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    LRO can try again in the next few months, when the sun position will be different (for example in 3 months the Earth's orbit moves 90 degrees, so the relative angle of the sun will move 90 degrees. LRO's polar orbit plane does NOT rotate relative to the sun, it's as though the sun "moves" 90 degrees in 3 months, in the relative sense)
     
  12. Sep 19, 2019 #12

    Winston

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    https://www.cnet.com/news/nasa-still-searching-for-indias-chandrayaan-2-vikram-moon-lander/

    This isn't the LRO's only shot at spotting Vikram. It will fly over again on Oct. 14 when lighting conditions are expected to be better. NASA said it will make the results of this week's flyover available as soon as possible.
     
  13. Oct 2, 2019 #13

    Winston

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  14. Oct 24, 2019 #14

    Winston

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    India's Crashed Moon Lander Is Still Missing, And NASA Can't Find It Anywhere
    24 Oct 2019

    https://www.sciencealert.com/india-...still-missing-and-nasa-can-t-find-it-anywhere

    Where oh where has India's moon lander gone? Over a month after Chandrayaan-2's Vikram lander had an unlucky crash landing, somewhere near the unexplored lunar south pole, NASA still can't seem to find any trace of it.

    After poring over a new set of images from the space agency's Lunar Reconnaissance Orbiter (LRO), its experts have come up empty-handed for the second time. Comparing images from before and after the crash, they say this region of the Moon appears altogether empty.

    A previous fly-by in September gave us no luck either, although at that time the images had been taken at dusk, so there were larger shadows on the terrain.

    These might very well have obscured the lander, and yet even in October, when the lighting was supposed to be more favourable, there was nothing to be seen.

    "It is possible that Vikram is located in a shadow or outside of the search area," John Keller, the deputy project scientist for the LRO mission, told the Press Trust of India.

    "Because of the low latitude, approximately 70 degrees south, the area is never completely free of shadows."

    Or maybe we simply aren't looking in the right spot. During it's 'hard' landing, India's space agency lost contact with the lander, and a cold night in this part of the Solar System is a death sentence for human machinery.

    A day after the crash, the Indian Space Research Organisation reported it had found the lander in a thermal image of the Moon, so maybe it is hiding in the shroud of a shadow after all.
    [So, WHY haven't we or, at least, NASA seen that image so that NASA would know EXACTLY the "right spot" to look in the visible light images? Is the claim of seeing it in IR actually BS done for reasons of national pride? - W]
     
  15. Nov 16, 2019 #15

    Winston

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    From Wikipedia:

    Radio transmissions from the lander were tracked during descent by analysts using a 25-meter radio telescope owned by the Netherlands Institute for Radio Astronomy. Analysis of the doppler data suggests that the loss of signal coincided with the lander impacting the lunar surface at a velocity of nearly 50 m/s (180 km/h) (as opposed to an ideal 2 m/s (7.2 km/h) touchdown velocity).[3][140]

    The powered descent was also observed by NASA's Lunar Reconnaissance Orbiter (LRO) using its Lyman-Alpha Mapping Project (LAMP) instrument to study changes in the lunar exosphere due to exhaust gases from the lander's engines.[141]

    The mission's orbiter was reported to have imaged the location of the lander.[142] Unconfirmed reports, citing an ISRO official, stated that the lander was intact,[143] but there has been no official announcement by ISRO on the lander's actual location or physical condition.[32][144] ISRO's Chairman, K. Sivan, tasked senior scientist P. S. Goel to head the Failure Analysis Committee to look into the causes of the failure.[145]

    Both ISRO and NASA attempted to communicate with the lander for about two weeks before the lunar night set in,[146][147] while NASA's Lunar Reconnaissance Orbiter (LRO) flew over on 17 September 2019 and acquired some images of the intended landing zone.[148] However, the region was near dusk, causing poor lighting for optical imaging.[149][150] NASA's LRO images, showing no sight of the lander, were released on 26 September.[132] The LRO flew over again on 14 October under more favorable lighting conditions,[151][152] but was unable to locate it.[153][154] The LRO performed a third flyover on November 10.[153]
     
  16. Dec 2, 2019 #16

    georgegassaway

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    Vikram Lander Found

    I guess India's space agency's idea of "Intact" goes along with Elon Musk's infamous "Hard Landing' description of the first attempt to land F9 into a barge (45 degree Kamikaze crash was more like it). Debris scattered for several kilometers.

    Source: http://lroc.sese.asu.edu/posts/1131...FESr1o7ElNtm-j9FTE4IC06lcmmwyHeBM_4ZuPiQOlTXQ


    "The Chandrayaan 2 Vikram lander was targeted for a highland smooth plain about 600 kilometers from the south pole; unfortunately the Indian Space Research Organisation (ISRO) lost contact with their lander shortly before the scheduled touchdown (7 September in India, 6th September in the United States). Despite the loss, getting that close to the surface was an amazing achievement. The LROC team released the first mosaic (acquired 17 September) of the site on 26 September and many people have downloaded the mosaic to search for signs of Vikram. Shanmuga Subramanian contacted the LRO project with a positive identification of debris. After receiving this tip the LROC team confirmed the identification by comparing before and after images. When the images for the first mosaic were acquired the impact point was poorly illuminated and thus not easily identifiable. Two subsequent image sequences were acquired on 14, 15 October and 11 November. The LROC team scoured the surrounding area in these new mosaics and found the impact site (70.8810°S, 22.7840°E, 834 m elevation) and associated debris field. The November mosaic had the best pixel scale (0.7 meter) and lighting conditions (72° incidence angle).

    The debris first located by Shanmuga is about 750 meters northwest of the main crash site and was a single bright pixel identification in that first mosaic (1.3 meter pixels, 84° incidence angle). The November mosaic shows best the impact crater, ray and extensive debris field. The three largest pieces of debris are each about 2x2 pixels and cast a one pixel shadow."



    [​IMG]
    "Vikram impact point and associated debris field. Green dots indicate spacecraft debris (confirmed or likely). Blue dots are locating disturbed soil, likely where small bits of the spacecraft churned up the regolith. "S" indicates debris identified by Shanmuga Subramanian. Portion of NAC mosaic made from images M1328074531L/R and M1328081572L/R acquired 11 November [NASA/GSFC/Arizona State University]."
     
    Last edited: Dec 2, 2019
  17. Dec 3, 2019 #17

    Marc_G

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    And so the mystery ends. It was a cool mission and I expect much will be learned from the failure analysis. Better luck next time.
     
  18. Dec 16, 2019 #18

    Winston

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    Old info and my search for it was made in early December. Haven't yet looked for newer stuff.

    Chandrayaan-2 landing: What went wrong with Vikram
    13 Sep 2019

    https://www.indiatoday.in/magazine/...hat-went-wrong-with-vikram-1598302-2019-09-13

    It was at this point that the second phase, termed the Absolute Navigation Phase (ANP) and lasting around 40 seconds, kicked in. In this phase, Vikram should have corrected any errors in calculations of the key navigation parameters such as its height and velocity during the Rough Braking Phase. It did this by double-checking the readings of its on-board measuring instruments, including cameras photographing the lunar terrain, to measure Vikram’s velocity and height. Variations in the velocity, altitude or inclination of the spacecraft were to be corrected by the autonomous control systems, which arrive at their own logical decisions on the adjustments that need to be made. As a senior scientists put it, The number of exigencies and errors you can calculate and feed into the computer is only limited by your imagination. The best control systems are the ones where scientists let their imaginations run free and plan for as many contingencies as possible.

    It was at the brief ANP phase that the anomalies in Vikram’s powered descent began to mount. In the control room, the large console simulating Vikram’s descent showed the lander deviating from its 45-degree inclination. It inexplicably executed a somersault, making the engines face upwards instead of downwards (see graphic: 15 Minutes to Despair). One explanation is that the onboard computer was correcting the spacecraft’s attitude to enable the cameras to position it properly for taking the pictures it needed to calibrate vital parameters. But that manoeuvre went haywire and resulted in increasing the vertical descent velocity rather than decreasing it. The other explanation is that the control system noticed a drop in the velocity and corrected it even though it was still within the threshold. In doing so, it first erroneously rotated the craft by 140 degrees to boost the velocity, then reversed it to the original position. By then, the spacecraft had lost its orientation and control.

    It was at this point that the third phase, the Fine Braking Speed Phase lasting 90 seconds, began. To bring down Vikram’s horizontal and vertical speeds to near-zero and the craft to an altitude of 400 metres, two of the four engines were to shut down. There is evidence to show that the spacecraft was desperately trying to regain its orientation and was pitching from side to side. The console showed that the vertical speed had increased; it was also at this juncture that all communication with the control room snapped. There was no evidence to show that the two engines had shut down as per plan. All the console showed was that the horizontal velocity was still a high 48 metres per second and the vertical velocity 59 metres per second. Both these key parameters should have been considerably lower for the lander to go into its terminal descent phase. Its speed at this point should have been near-zero and it should have been hovering over the lunar surface at a height of 400 metres. Its onboard cameras were then to take pictures for its control system to check whether the landing site was suitable.

    According to experts, Vikram’s abrupt end can be attributed to three major reasons, but they do not quite agree which one was the main culprit. Some believe that the propulsion systems malfunctioned during the transition from the Rough Brake Phase to the Absolute Navigation Phase, when the engines were to fire synchronously to reduce the lander’s speed. Since the throttle-able engines were based on a new technology, there is suspicion that one of them could have misfired, causing unstable conditions beyond the system’s tolerance, and confused the command and control system. Others believe the error lay in the control system itself, with an improper logic built in, that made the lander do a complete turn during the transition between the absolute navigation and fine braking phases. Yet another section of opinion argues that it was a combination of errors in both propulsion and control systems that led to the setback. Meanwhile, ISRO scientists are gathering every bit of data the lander transmitted before its signal was lost. They are using such data to simulate all possible scenarios and explain Vikram’s aborted landing.


    What Failed ‘Vikram’: Decoding the Jargon in Govt’s Chandrayaan-2 Reply in Lok Sabha
    23 Nov 2019

    Experts say the reasons why lander Vikram dropped speed too fast and landed off-target need to be investigated for a successful Chandrayaan-3 mission, which in turn would help in the manned Gaganyaan mission.

    https://www.news18.com/news/india/w...chandrayaan-2-reply-in-lok-sabha-2397605.html

    This is the first official statement on what went wrong with the moon-lander that kept the entire nation hooked two months ago. [which they don't provide a link to - W]

    So what could have actually gone wrong?

    "Actually, you just can't conclude anything based on that information," says Ajay Lele, senior Fellow at the Institute of Defence Studies and Analyses. "There are two or three broad options. It could be a mechanical failure, or a problem with controlling the velocity, or a problem with the firing of the engines. A fourth option could be that they were not prepared for some eventuality that could have happened," he added.

    Former ISRO scientist Dr Mukund Rao points out that the specific sentence “reduction in velocity was more” points to the real problem of Chandrayaan-2's 'Vikram' lander soft-landing phase. It clearly shows that the lander slowed down faster than envisaged and “touched-down” on lunar surface much ahead from the landing point, naturally hard on the surface.

    When the velocity/speed should have reduced gradually ideally, it dropped speed too fast and could not make the soft-landing. "Basically it lost velocity much faster and stopped much ahead, half a kilometer from its designated point. In common parlance, “braking” was too hard and it would have been a “rough” coasting to land hard. But the question is why did that happen? Why did velocity reduce much faster? Were such conditions anticipated and were there any correction mechanisms planned in the mission?” asks Dr Rao, currently an Adjunct Professor at the National Institute of Advanced Studies.

    According to Rao, there are few key things to look at for the Vikram's missed landing -- the thrusters (akin to braking system) and control/guidance systems did not function as per plan. It looks like they “over-worked” and thus failed to make the soft-landing path; the lunar gravitation forces need to be well understood and modelled into the landing, especially at South Pole. Sufficient gravity and other data and their analyses are essential; the real-time and precise/detailed knowledge of the lunar terrain at landing area and their real-time modelling into the trajectory and velocity management. These aspects must have been looked into to understand the problem in more detail,” he said.

    Chandrayaan-2 orbiter page

    https://www.isro.gov.in/chandrayaan2-latest-updates
     
  19. Dec 16, 2019 #19

    mpitfield

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    "Slowed down too fast" Yeah I guess, but then there was that end over end death tumble to deal with.
     

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