NASA’s Lunar Reconnaissance Orbiter (LRO) has successfully pinged India’s Chandrayaan-3 lander Vikram on the lunar surface, designating it as a landmark for future Moon missions. Vikram, which crash-landed on the Moon in 2019, is now serving as a location marker near the lunar south pole.
Chandrayaan-3 Lander Sends Laser Pulses to NASA Orbiter
On January 18, Chandrayaan-3’s laser retroreflector array instrument bounced back laser pulses from LRO’s laser altimeter. This exchange of signals confirmed that Vikram can now function as a passive laser ranging retroreflector, allowing spacecrafts to accurately determine their location while orbiting the Moon.
The feat was achieved when LRO flew over Vikram’s landing site at an altitude of 100 km. LRO’s laser altimeter fired laser pulses at Vikram and then detected the returning pulses. This is the first time LRO has laser ranged to any lunar surface landing site with a passive laser retroreflector.
- Date of ping: January 18, 2024
- Spacecraft involved:
- Chandrayaan-3 lander Vikram (on lunar surface)
- NASA's Lunar Reconnaissance Orbiter (in lunar orbit at 100 km altitude)
- Instruments used:
- Vikram's laser retroreflector array
- LRO's laser altimeter
- Outcome: Successful exchange of laser pulses, designating Vikram as south pole marker
New Style of Locating Targets on Moon Demonstrated
The successful experiment has opened doors to a new approach of precisely locating targets on the Moon using laser beams.
So far, laser altimeters have been used to measure altitudes and create terrain maps of celestial objects. But now, pairing them with small laser reflectors on spacecrafts creates an opportunity for improved tracking and navigation.
In the future, laser reflector arrays planted on the Moon’s surface could guide spacecrafts to precise landing sites. Passive laser retroreflectors require no power and can function for decades, providing durable and maintenance-free navigation infrastructure.
Why Designate Vikram as Lunar South Pole Marker?
The lunar south pole has gained immense scientific and exploration interest in recent years due to the confirmation of water ice in permanently shadowed regions. Future human outposts on the Moon are likely to be established in this region.
However, landing site selection requires identification of appropriate landmarks for guidance, navigation and spatial orientation. Vikram’s position near the south pole makes it strategically valuable real estate.
Its successful laser ranging with LRO proves it can serve as a reliable marker, against which relative position and altitude measurements can be made by overhead spacecrafts. This will assist with mapping landing sites of interest, characterizing illumination conditions, and landing site accessibility.
Background: Vikram’s Story So Far
Vikram was the lander component of India’s Chandrayaan-2 mission, launched in 2019 to explore the south polar region of the Moon. It attempted a soft landing on September 7 near the lunar south pole. Unfortunately, Vikram lost contact with ground control during its descent and crash landed on the Moon.
The site of Vikram’s crash landing was located in 2022 through NASA’s public crowdsourcing effort. While the main Chandrayaan-2 orbiter continues to function in lunar orbit, the lander Vikram lying on the Moon was assumed to be dead.
Key timeline of Vikram lander:
July 2019: Launched aboard Chandrayaan-2 orbiter
Sep 7, 2019: Attempted soft landing, crash landed on lunar surface
2022: Crash site identified via NASA's crowdsourcing
2024: Revived as south pole marker through laser ranging demo with LRO
What Next for Vikram Lander?
While Vikram itself may never function again as an active scientific instrument, its laser retroreflector array has now breathed unexpected new life into India’s lunar landing ambitions.
It will serve as a valuable asset for NASA’s Artemis program and other future Moon missions by providing a precisely located navigation marker on the lunar frontier.
Its success proves the value of integrating basic retroreflectors in future lunar landers and rovers, enabling tracking from lunar orbit through laser beams.
Outcome is a Win for International Cooperation
The lunar laser ranging experiment was the result of a collaborative effort between NASA and ISRO, combining capabilities of Chandrayaan-3 and LRO. Its success highlights the immense dividends reaped when space agencies pool resources and expertise to push scientific boundaries.
As humanity gears up to return humans to the Moon and establish long-term presence through the Artemis program, such international partnerships will be key. Chandrayaan-3 and LRO have set a great precedent for future collaborative lunar exploration.
Their joint experiment has expanded the bag of tricks for precise Moon navigation using lasers. With luck, someday human astronauts may directly benefit from Vikram’s resurrection as a humble passive reflector guiding their ships to the south pole.
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