Launch a rocket to welcome the Spring Festival! If you want to understand the Land Exploration No. 1 Group A, you need to know these keywords

Video source: China Aerospace Science and Technology Corporation Eighth Academy

At 7:44 am on January 26, at the Jiuquan Satellite Launch Center in my country, the Long March 4B carrier rocket ignited and took off, sending the Land Exploration No. 1 Group A satellite into the predetermined orbit. The launch mission was a complete success.

▲ Land Exploration No. 1 Group A Satellite Rendering

Image source: China Aerospace Science and Technology Corporation Eighth Academy

The Land Exploration No. 1 Group A satellite can measure millimeter-level deformation of the earth's surface thousands of miles away in space, and at the same time carry out surface deformation monitoring and topographic mapping, providing support for my country's independent satellite detection and prevention of geological disasters, safeguarding national resources and protecting ecological security.

To understand it, you can use the following keywords:

"Having Brothers": They can both "guard their own side" and "dance socially"

The "Land Exploration No. 1 01 Group" consists of two completely identical satellites, A and B. Satellite A is not an "only child". Its brother, the completely identical satellite B, is scheduled to be launched at an appropriate time at the end of February this year.

After the two satellites are networked, Satellite A and Satellite B can serve as each other's "protagonist" and "supporting role", and carry out work in two in-orbit flight modes, namely following and circling, to respectively realize repeated orbit differential interferometry deformation measurement and interferometric topography mapping, with the surface deformation measurement accuracy reaching millimeter level.

Wei Chun, deputy chief designer and executive chief engineer of the Land Exploration No. 1 Group 01 satellite, vividly compared the double-satellite flyby mode to "ballroom dancing" - one satellite flies in orbit, and the "dance partner" flies on its left or right side, and the two satellites look in the same direction together.

"Penetrable": Penetrating the trees

The Land Exploration No. 1 Group A satellite fills many gaps in China's L-band synthetic aperture radar satellite field. Its "penetration power" is worth mentioning.

Penetration ability mainly depends on wavelength. The wavelength of L-band radar is about 23 cm, which has better penetration into vegetation and can adapt to the characteristics of China with many mountains and wide forest coverage.

"For example, when observing the forest surface, the L-band signal can penetrate 20-meter-high trees and accurately measure the ground height, rather than just the forest height," said Wei Chun, deputy chief designer and executive chief engineer of the Land Exploration No. 1 Group 01 satellite.

“See clearly”: Largest caliber

In addition to being able to "penetrate", a satellite must also have "eagle eyes" to be able to "see the earth with millimeter accuracy from thousands of miles away".

The Land Exploration No. 1 Group A satellite that is heading to space this time is equipped with a SAR (SAR refers to: synthetic aperture radar) antenna with a total area of ​​more than 33 square meters. It is currently China's largest SAR satellite in orbit. Its ground observation resolution reaches the meter level, and its deformation measurement accuracy reaches the millimeter level.

The launch of "Land Exploration No. 1 Group A" will enable China to independently control differential interferometry SAR data, and significantly reduce its dependence on foreign SAR data for geological, earthquake, emergency and other industry applications.

When the "Land Exploration No. 1 Group B" is launched, the A and B satellites will form a "large-caliber combination" in space, adding powerful tools to China's geological disaster monitoring.

This launch is the 407th launch of the Long March series of launch vehicles.

▲ The Long March 4B rocket stands on the tower (Photo by Yan Pengfei)

The Long March 4B rocket is a room-temperature liquid three-stage carrier rocket developed by the Eighth Academy. It has the ability to launch satellites of various types and with different orbital requirements. It can carry out multiple satellite launches with one rocket, and its sun-synchronous orbit carrying capacity can reach 3 tons.

Comprehensive sources: China Aerospace Science and Technology Corporation, Science and Technology Daily, China News Network, China Aerospace News, etc.