After a journey from Earth to lunar orbit that took nearly six weeks, India will try to land on the moon’s surface. With Chandrayaan-2, the country hopes to become the fourth in the world to complete a lunar landing, after the Soviet, American and Chinese space programs.
Here’s what you need to know about the Chandrayaan-2 mission and how to follow it.
The landing is scheduled for between 4 and 5 p.m. Friday New York time. (In India, it will already be Saturday, between 1:30 and 2:30 a.m.)
Doordarshan, a public broadcasting network in India, will also provide live video of the landing.
The spacecraft consists of multiple pieces:
A lander named Vikram, after Vikram A. Sarabhai, the father of the Indian space program.
A six-wheeled rover named Pragyan, which means “wisdom” in Sanskrit.
On Monday, the lander carrying the rover detached from the orbiter.
The rover carries a couple of instruments to measure the composition of moon rocks and soil. The lander carries instruments to measure moonquakes, temperatures a couple of inches into the soil and charged particles from the sun in the extremely tenuous lunar atmosphere.
The lander and rover are expected to operate just a couple of weeks; they were not designed to survive the frigid darkness of night, which lasts two weeks.
The orbiter carries a suite of instruments, including cameras and spectrometers, and is designed to operate at least a year.
For people in India, the space program is a demonstration of their country’s emerging technological capabilities. The Chandrayaan-2 lander and rover will explore a spot near the lunar South Pole, which is an intriguing region that no one has seen up close yet. Water ice exists deep within eternally shadowed craters near the poles.
Chandrayaan-2 will be heading not into a crater but instead to a high plain between two craters.
Most of space is empty. If something goes wrong with a spacecraft, it usually shuts itself down and waits for instructions from Earth. Landing is different.
By design, moon landers are put on a collision course with their destinations; the trick is to make the collision gentle enough that it sets down in one piece. To do this, thrusters on the lander need to fire at the right times in the right directions for the desired length of time.
If something goes wrong during descent — the spacecraft’s computer crashes or a thruster malfunctions — there may not be time to recover.
The moon is more than 200,000 miles from Earth, which means any instructions from the engineers in India take more than one second to reach the spacecraft. Because of the delay, the landing is automated, with the spacecraft acting on its own.
In addition to slowing down as it descends, the lander also has to avoid any craters and boulders so that it does not tip over. The landing area was chosen in part because it appears flat and smooth. The variety of things that could go wrong have led K. Sivan, the director of India’s space program, to call the landing phase “15 minutes of terror.”
The moon is littered with the remains of spacecraft that have tried and failed to land in one piece. Two American spacecraft, from the robotic Surveyor series that helped blaze the trail for Apollo, crashed in the 1960s. Several probes from the Soviet Luna program also impacted the moon. Beresheet, a spacecraft built by an Israeli nonprofit, crashed in April after a command was incorrectly sent as it landed.
If India sticks the landing on its first try, it will highlight the technological accomplishment of the mission.
It is Hindi for “moon vehicle.”
As the 2 in Chandrayaan-2 indicates, India has already sent one spacecraft to the moon. The orbiter Chandrayaan-1, launched in 2008, operated for 10 months and helped confirm the presence of water ice in the lunar craters.
India also launched an orbiter to Mars in 2013 that continues to orbit the red planet, and in 2017, an Indian rocket deployed 104 satellites, a record for a single launch.
India’s space missions have cost a fraction of those from bigger space agencies like NASA and the European Space Agency, but they have also generally carried simpler payloads. That is also true of Chandrayaan-2, which cost less than $150 million.
In March, India also demonstrated a less friendly space capability, an antisatellite test that scattered hundreds of pieces of debris. China, the United States and Russia have developed similar weapons.
ISRO’s plans include additional robotic missions to Venus, Mars, the moon and the sun.
India is also working on flying its astronauts to Earth orbit on Gaganyaan, or “orbital vehicle.” A crewless test is scheduled for December of next year; the first flight with people aboard is scheduled for 2022.