Pragyan (rover)

Pragyan (Sanskrit: प्रज्ञान, romanized: prajñana, lit. 'wisdom'[5][6] Pronunciation [7][8]) was the rover of Chandrayaan-2, a lunar mission developed by the Indian Space Research Organisation (ISRO),[9] that launched in July 2019. Pragyan was destroyed along with its lander, Vikram, when it crash-landed on the Moon in September 2019 and never got the chance to deploy.[2][10]

Pragyan
Illustration of Chandrayaan's rover Pragyan
Mission typeLunar rover
OperatorISRO
Mission duration≤ 14 days (intended);
Achieved: 0 days (landing failure)
Spacecraft properties
ManufacturerISRO
Landing mass27 kg (60 lb)
Dimensions0.9 m (3.0 ft) × 0.75 m (2.5 ft) × 0.85 m (2.8 ft)
Power50 W from solar panels
Start of mission
Launch date22 July 2019 (2019-07-22) 14:43:12 IST, (09:13:12 UTC)
RocketGSLV Mk III M1
Launch siteSDSC Second launch pad
ContractorISRO
Deployed fromChandrayaan-2/Vikram lander
Deployment dateIntended: 7 September 2019[1]
Result: Never deployed from destroyed lander.[2]
Lunar rover
Landing date6 September 2019, 20:00-21:00 UTC[3]
Landing siteAttempted: 70.90267°S 22.78110°E [4] (Intended)
Crash landing at least 500m away from planned site. (Actual)
Distance covered500 m (1,600 ft) (intended)
 

Overview

The rover's mass was about 27 kg (60 lb) and was designed to operate on solar power.[11][12] The rover was to move on 6 wheels traversing 500 meters on the lunar surface at the rate of 1 cm per second, performing on-site analysis and sending the data to the Vikram lander, which would have relayed it to the Earth station.[13][14][15][16][17] For navigation, the rover was equipped with:

  • Stereoscopic camera-based 3D vision: two 1 megapixel, monochromatic NAVCAMs in front of the rover to provide the ground control team a 3D view of the surrounding terrain, and help in path-planning by generating a digital elevation model of the terrain. IIT Kanpur contributed to the development of the subsystems for light-based map generation and motion planning for the rover.[18]
  • Control and motor dynamics: the rover design has a rocker-bogie suspension system and six wheels, each driven by independent brushless DC electric motors. Steering is accomplished by differential speed of the wheels or skid steering.[19]

The expected operating time of Pragyan rover was one lunar day or around 14 Earth days, as its electronics were not designed to endure the frigid lunar night. Its power system had a solar-powered sleep/wake-up cycle implemented, which could have resulted in longer service time than planned.[20][21]

  • Dimensions: 0.9 × 0.75 × 0.85 m[22]
  • Power: 50 W[22]
  • Travel speed: 1 cm/sec.[22]
  • Planned mission duration: ≤14 days (one lunar day)

Planned landing site
Landing site[4] Coordinates
Prime landing site 70.90267°S 22.78110°E / -70.90267; 22.78110
Alternate landing site 67.87406°S 18.46947°W / -67.87406; -18.46947

Two landing sites were selected, each with a landing ellipse of 32 km x 11 km.[4] The prime landing site (PLS54) was at 70.90267 S 22.78110 E (~350 km north of the South Pole-Aitken Basin rim[23][4]), and the alternate landing site (ALS01) was at 67.874064 S 18.46947 W. The prime site was on a high plain between the craters Manzinus C and Simpelius N,[24][23] on the near side of the Moon.[4] The criteria used to select the landing zones were: south polar region, on the near side, slope less than 15 degrees, boulders less than 50 cm (20 in), crater and boulder distribution, sunlit for at least 14 days, nearby ridges do not shadow the site for long durations.[4]

The planned landing site and its alternate site, are located within the polar LQ30 quadrangle. The surface likely consists of impact melt, possibly mantled by ejecta from the massive South Pole–Aitken basin and mixing by subsequent nearby impacts.[25] The nature of the melt is mostly mafic,[25] meaning it is rich in silicate mineral, magnesium and iron. The region could also offer scientifically valuable rocks from the lunar mantle if the basin impactor excavated all the way through the crust.[26]

Crash landing

The Vikram lander, carrying the Pragyan rover, separated from the Chandrayaan-2 orbiter on 7 September 2019 and was scheduled to land on the Moon at around 1:50 a.m. IST. The initial descent was considered within mission parameters, passing critical braking procedures as planned. The descent and soft-landing was to be done by the on-board computers on Vikram, with mission control unable to make corrections.[27]

The lander's trajectory began to deviate at about 2.1 kilometres (1.3 mi; 6,900 ft) above the surface.[28] The final telemetry readings during ISRO's live-stream show that Vikram's final vertical velocity was 58 m/s (210 km/h) from 330 meters above the surface which, according to the MIT Technology Review, is "quite fast for a lunar landing."[29] Initial reports suggesting a crash,[30][31] have been confirmed by ISRO chairman K. Sivan, stating that the lander location had been found, and "it must had been a hard landing".[10][32][33] The Lunar Reconnaissance Orbiter took images of the crash site, showing that the lander and the Pragyan rover inside the lander had been destroyed by the impact, creating an impact site and debris field spanning kilometres.[34]

The orbiter part of the mission, with eight scientific instruments, remains operational and will continue its seven-year mission to study the Moon.

See also

References
  1. "Live media coverage of the landing of Chandrayaan-2 on lunar surface - ISRO". www.isro.gov.in. Retrieved 2019-09-02.
  2. "Chandrayaan - 2 Latest Update". isro.gov.in. September 7, 2019. Retrieved September 11, 2019.
  3. "Chandrayaan-2 update: Fifth Lunar Orbit Maneuver". Indian Space Research Organisation. September 1, 2019. Retrieved September 1, 2019.
  4. Amitabh, S.; Srinivasan, T. P.; Suresh, K. (2018). Potential Landing Sites for Chandrayaan-2 Lander in Southern Hemisphere of Moon (PDF). 49th Lunar and Planetary Science Conference. 19–23 March 2018. The Woodlands, Texas. Bibcode:2018LPI....49.1975A. Archived from the original (PDF) on 22 August 2018.
  5. "Chandrayaan-2 Spacecraft". Retrieved 24 August 2019. Chandrayaan 2's Rover is a 6-wheeled robotic vehicle named Pragyan, which translates to 'wisdom' in Sanskrit.
  6. Wilson, Horace Hayman (1832). A dictionary in Sanscrit and English. Calcutta: Education Press. p. 561.
  7. Elumalai, V.; Kharge, Mallikarjun (7 Feb 2019). "Chandrayaan - II" (PDF). PIB.nic.in. Archived from the original (PDF) on 7 February 2019. Retrieved 7 Feb 2019. Lander (Vikram) is undergoing final integration tests. Rover (Pragyan) has completed all tests and waiting for the Vikram readiness to undergo further tests.
  8. "Chandrayaan-2 Spacecraft". Retrieved 24 August 2019. Chandrayaan 2's Rover is a 6-wheeled robotic vehicle named Pragyan, which translates to 'wisdom' in Sanskrit.
  9. ""Chandrayaan-2 launch between July 9 and 16: Isro"".
  10. Vikram lander located on lunar surface, wasn't a soft landing: Isro. Times of India. 8 September 2019.
  11. "Chandrayaan-2 to Be Launched in January 2019, Says ISRO Chief". Gadgets360. NDTV. Press Trust of India. 29 August 2018. Retrieved 29 August 2018.
  12. "ISRO to send first Indian into Space by 2022 as announced by PM, says Dr Jitendra Singh" (Press release). Department of Space. 28 August 2018. Retrieved 29 August 2018.
  13. "ISRO to Launch Chandrayaan 2 on July 15, Moon Landing by September 7". The Wire. Retrieved 2019-06-12.
  14. Singh, Surendra. "Chandrayaan-2 will carry 14 payloads to moon, no foreign module this time". The Times of India – TNN. Retrieved 2019-05-11.
  15. "Payloads for Chandrayaan-2 Mission Finalised" (Press release). Indian Space Research Organisation. 30 August 2010. Retrieved 4 January 2010.
  16. "Chandrayaan-2 to get closer to moon". The Economic Times. Times News Network. 2 September 2010. Archived from the original on 12 August 2011.
  17. Ramesh, Sandhya (12 June 2019). "Why Chandrayaan-2 is ISRO's 'most complex mission' so far". ThePrint. Retrieved 12 June 2019.
  18. "With robot hands, IIT-K profs bring joy to paralytics". The Times of India. 2019. Retrieved 2019-07-10.
  19. Annadurai, Mylswami; Nagesh, G.; Vanitha, Muthayaa (28 June 2017). ""Chandrayaan-2: Lunar Orbiter & Lander Mission", 10th IAA Symposium on The Future of Space Exploration: Towards the Moon Village and Beyond, Torin, Italy". Archived from the original on 28 June 2017. Retrieved 14 June 2019. Mobility of the Rover in the unknown lunar terrain is accomplished by a Rocker bogie suspension system driven by six wheels. Brushless DC motors are used to drive the wheels to move along the desired path and steering is accomplished by differential speed of the wheels. The wheels are designed after extensive modelling of the wheel-soil interaction, considering the lunar soil properties, sinkage and slippage results from a single wheel test bed. The Rover mobility has been tested in the Lunar test facility wherein the soil simulant, terrain and the gravity of moon are simulated. The limitations w.r.t slope, obstacles, pits in view of slippage/sinkage have been experimentally verified with the analysis results. Alt URL
  20. "Dr M Annadurai, Project director, Chandrayaan 1: 'Chandrayaan 2 logical extension of what we did in first mission'". The Indian Express. 2019-06-29. Retrieved 2019-06-30.
  21. Payyappilly, Baiju; Muthusamy, Sankaran (17 January 2018). "Design framework of a configurable electrical power system for lunar rover". ResearchGate: 1–6. doi:10.1109/ICPCES.2017.8117660. ISBN 978-1-5090-4426-9.
  22. "Launch kit at a glance".
  23. Geological Insights into Chandrayaan-2 Landing Site in the Southern High Latitudes of the Moon. Rishitosh K. Sinha, Vijayan Sivaprahasam, Megha Bhatt, Harish Nandal, Nandita Kumari, Neeraj Srivastava, Indhu Varatharajan, Dwijesh Ray, Christian Wöhler, and Anil Bhardwaj. 50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132).
  24. Chandrayaan-2: How 'Lander Vikram' will touchdown on the moon? Srishti Choudhary, Live Mint 14 July 2019.
  25. Update on the Geologic Mapping of the Lunar South Pole Quadrangle (LQ-30): Evaluating Mare, Cryptomare and Impact Melt Deposits. S. C. Mest, D. C. Berman, N.E. Petro, and R. A. Yingst. 46th Lunar and Planetary Science Conference (2015).
  26. As India prepares for another Moon mission, here is what makes Chandrayaan-2 special. Sandhya Ramesh, The Print. 14 July 2019.
  27. Chandrayaan 2: Here's everything about ISRO Moon-landing its Vikram lander. Financial Express. Ribhu Mishra, 7 September 2019.
  28. India Just Found Its Lost Vikram Lander on the Moon, Still No Signal. Tariq Malik ,Space. 8 September 2019.
  29. Neel V. Patel (6 September 2019). "India's Chandrayaan-2 lander likely crashed into the moon's surface". MIT Technology Review. Retrieved 7 September 2019.
  30. India's Moon Mission Continues Despite Apparent Lander Crash. Mike Wall, Space. 7 September 2019. Quote: "India's Moon Mission Continues Despite Apparent Lander Crash."
  31. "India's Vikram Spacecraft Apparently Crash-Lands on Moon". www.planetary.org. Retrieved 7 September 2019.
  32. "Lander Vikram located: K Sivan". www.aninews.in. Retrieved 2019-09-08.
  33. Schultz, Kai (8 September 2019). "India Says It Has Located Chandrayaan-2 Lander on Moon's Surface". The New York Times. Retrieved 8 September 2019.
  34. https://www.theguardian.com/science/2019/dec/03/indias-crashed-vikram-moon-lander-spotted-on-lunar-surface
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