Pragyan (rover)

Pragyan

Pragyan mounted on the ramp of the Chandrayaan-2 lander
Mission type	Lunar rover
Operator	ISRO
COSPAR ID	{{#property:P247}}
Mission duration	Chandrayaan-2: 0 days (landing failure) Chandrayaan-3: 2 years, 11 months and 26 days (elapsed)
Spacecraft properties
Manufacturer	ISRO
Landing mass	Chandrayaan-2: 27 kg (60 lb) Chandrayaan-3: 26 kg (57 lb)
Dimensions	0.9 m × 0.75 m × 0.85 m (3.0 ft × 2.5 ft × 2.8 ft)
Power	50 W from solar panels
Start of mission
Launch date	Chandrayaan-2: 22 July 2019 (2019-07-22) 14:43:12 IST (09:13:12 UTC) Chandrayaan-3: 14 July 2023 (2023-07-14) 14:35 IST (09:05 UTC)
Rocket	LVM3 M1, LVM3 M4
Launch site	SDSC Second launch pad
Contractor	ISRO
Deployed from	Vikram
Deployment date	Chandrayaan-2: Intended: 7 September 2019 Result: Never deployed from destroyed lander. Chandrayaan-3: 23 August 2023
Lunar rover
Landing date	6 September 2019, 20:00–21:00 UTC
Landing site	Attempted: 70.90267°S 22.78110°E (Intended) Crash landing at least 500m away from planned site. (Actual)
Distance covered	500 m (1,600 ft) (intended)
Chandrayaan programme

Pragyan (from Sanskrit: प्रज्ञानम्, romanized: prajñānam, lit. 'wisdom') is a lunar rover that forms part of Chandrayaan-3, a lunar mission developed by the Indian Space Research Organisation (ISRO). A previous iteration of the rover was launched as part of Chandrayaan-2 on 22 July 2019 and was destroyed with its lander, Vikram, when it crashed on the Moon on 6 September. Chandrayaan-3 launched on 14 July 2023, carrying new versions of Vikram and Pragyan, which successfully landed near the lunar south pole on 23 August.

Overview

Schematic view of the rover

Pragyan has a mass of about 27 kg (60 lb) and dimensions of 0.9 m × 0.75 m × 0.85 m (3.0 ft × 2.5 ft × 2.8 ft), with a power output of 50 watts. It is designed to operate on solar power. The rover moves on six wheels and is intended to traverse 500 m (1,600 ft) on the lunar surface at the rate of 1 cm (0.39 in) per second, performing on-site analysis and sending the data to its lander for relay back to the Earth. For navigation, the rover is 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.
• 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.

The expected operating time of the rover is one lunar day or around 14 Earth days, as its electronics are not designed to endure the frigid lunar night. Its power system has a solar-powered sleep and wake-up cycle, which could result in a longer operation time than planned.

Chandrayaan-2 (2019)

Further information: Chandrayaan-2

Planned landing site

Two landing sites were selected in the lunar south polar region, each with a landing ellipse of 32 km × 11 km (19.9 mi × 6.8 mi). The prime landing site (PLS54) is at 70.90267°S 22.78110°E / -70.90267; 22.78110, approximately 350 km (220 mi) north of the rim of the South Pole–Aitken basin. The alternative landing site (ALS01) is at 67.87406°S 18.46947°W / -67.87406; -18.46947. The prime site is on a high plain between the craters Manzinus C and Simpelius N, on the near side of the Moon. The criteria used to select the landing zones were a location in the south polar region and on the near side, a slope less than 15 degrees, with boulders less than 50 cm (20 in) in diameter, a crater and boulder distribution, being sunlit for at least 14 days, and with nearby ridges not shadowing the site for long durations.

Both the planned site and the alternative 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. The nature of the melt is mostly mafic, meaning it is rich in silicate minerals, 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.

Crash landing

The lander Vikram, carrying Pragyan, 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 and thus it impacted the lunar surface.

The lander's trajectory began to deviate at about 2.1 kilometres (1.3 mi; 6,900 ft) above the surface. The final telemetry readings during ISRO's live-stream show that Vikram's final vertical velocity was 58 m/s (210 km/h) at 330 m (1,080 ft) above the surface, which according to the MIT Technology Review was "quite fast for a lunar landing". Initial reports suggesting a crash, were later confirmed by ISRO chairman K. Sivan, stating that the lander location had been found, and "it must had been a hard landing". The Lunar Reconnaissance Orbiter took images of the crash site, showing that the lander had been destroyed by the impact, creating an impact site and debris field spanning kilometres.

Chandrayaan-3 (2023)

A 4-meter diameter crater, as captured by the Navigation camera onboard the rover.

Chandrayaan-3 was launched aboard an LVM3-M4 rocket on 14 July 2023, at 09:05 UTC from Satish Dhawan Space Centre Second Launch Pad in Sriharikota, Andhra Pradesh, India. On 23 August 2023, as the lander approached the low point of its orbit, its four engines fired as a braking manoeuvre at 30 kilometres (19 mi) above the Moon's surface. After 11.5 minutes, the lander was 7.2 km (4.5 miles) above the surface; it maintained this altitude for about 10 seconds, then stabilized itself using eight smaller thrusters and rotated from a horizontal to a vertical position while continuing its descent.

It then used two of its four engines to slow its descent to roughly 150 metres (490 ft); it hovered there for about 30 seconds and located an optimal landing spot before continuing downward and touching down at 12:32 UTC.

Since reaching the moon's south pole, Chandrayaan-3 deployed the rover to explore the cratered surface, harnessed integrated cameras to send back videos of its environment, and even started working on the research objectives planned for a two-week stay on the moon.

The first video of the rover, posted on 25th August 2023, showed it leaving the Vikram lander on a ramp and driving onto the Moon. ISRO posted the video in a thread on X that also included footage from the lander approaching its landing site and kicking up dust as it touched down on the surface. ISRO wrote afterwards that the rover’s two scientific instruments had been turned on and that it had moved eight meters.

On 26th August, ISRO posted a new video, shot from the lander, of the rover’s drive away, moving almost out of the lander’s sight. On 27th August, it published two pictures after the rover encountered a large crater positioned 3 metres ahead of it's location. However, the rover safely headed on a new path afterwards.

See also

• Artemis program, NASA's lunar program
• Luna-Glob, Russian lunar program
• Rover (space exploration)