In the recent hit science fiction TV series "The Vast Sky", a special group of human beings was conceived, due to the migration of the asteroid belt of the solar system, they lived in a low-gravity environment for generations, making their bodies extremely thin and tall, and they could no longer withstand the gravity of the earth, and could not even stand on their own on the earth.
Such a delicate background concept seems to mean that human colonization of asteroids is just around the corner, but in fact, human understanding of asteroids is very limited, especially for the Trojan asteroid group located in the outer solar system and in orbit with Jupiter. However, with the successful launch of nasa's Lucy asteroid probe on October 16, this "blind spot of human knowledge" may be refreshed.
The Lucy probe will detect eight asteroids
Detection of planetary "fossil craters"
01
According to US media reports, "Lucy" will fly over 1 main belt asteroid and 7 Trojan asteroids orbiting the sun in the same orbit as Jupiter over a period of 12 years. This will be the first time in the history of human spaceflight that the Trojan asteroid group has been explored, and it is expected to set a record for the number of 8 asteroids detected by the next mission.
In the science fiction drama mentioned at the beginning of the article, the human colonized asteroid is the main belt asteroid that we are more familiar with, which gathers in the orbit between Mars and Jupiter, like a "demarcation belt" dividing the solar system into "inner solar system" and "outer solar system". The Jupiter Trojan asteroid group, which Lucy focuses on, is not a main-belt asteroid, but is concentrated in the distant outer solar system. What is even more special is that the Trojan asteroid and Jupiter "co-orbit", rotating around the sun along the same orbit, but unlike the uniform distribution of main-belt asteroids, Trojan asteroids are divided into two groups of Jupiter front and back, clustered at the fourth and fifth Lagrange points of the Sun and Jupiter respectively.
The asteroid belt between Mars and Jupiter
The reason why Lucy specifically probed this asteroid is because according to the current model of planet formation and evolution, the Trojan asteroid is likely to be the original material that formed the planets of the outer solar system (wood, earth, sky, sea). Because they have been clustered in a stable environment at the Lagrange point, it is likely that they have retained the original state of the solar system nearly 4 billion years ago.
These primordial objects, like "fossils," provide important clues to deciphering the history of the solar system and the environment in which all planets, including Earth, formed and developed.
This is also like the name of the detector "Lucy", taken from a Australopithecus Alpha archaic human fossil discovered in 1974, which is considered to be the earliest "human" fossil found so far, and the discovery of this fossil has greatly revolutionized human understanding of its origin. "Lucy" is named after the probe, hoping that the probe can innovate human understanding of the origin and early days of the solar system through the study of Trojan asteroids.
Surprisingly, although the history of the Trojan asteroid is uniform and long, the astral composition is diverse. Based on the results of the spectral analysis, the probe alone will involve carbonaceous (C-type) and asteroids that may contain organic matter (D, P), in addition to metallic and siliceous asteroids. This diversity could mean that they form at different locations in the solar system and are "transported" to their current orbits as planets form and evolve.
Therefore, the goal of Lucy's scientific mission is to use the scientific payload it carries to obtain the shape and reflectivity of the detection target, to map the distribution of crater space, size and frequency; to determine the nature of the crust structure and stratification, and to estimate the relative age of the asteroid's surface.
In addition, Lucy will scan the composition and soil properties of the asteroid's surface to determine the distribution of minerals, ice and organic matter, as well as obtain mass and density data on the asteroid's interior, and explore the composition of the ground through the detection of craters, cracks, ejecta and bare beds.
Load save money with "old goods"
02
While the Lucy mission is ambitious, the project itself is not huge, costing just $981 million as a mission to NASA's Discovery-level planetary science program, a far cry from the nearly $10 billion James Webb telescope, which will be launched in December. "Lucy" adhering to the idea of "spending less and doing more", was first proposed in 2014, officially approved for implementation in 2017, and successfully lifted off 4 years later.
The Lucy probe is assembled and tested at the plant
The reason why "Lucy" takes a short time and has a high efficiency-cost ratio is mainly to make full use of existing technical resources. The probe is turnkey by Lockheed Martin, the probe platform inherits the Osiris-Rex asteroid sample return probe, and the scientific payload fuses New Horizons and Osiris-Rex with a proven chemical propulsion scheme.
The probe, which emits a launch weight of 1550 kg and a dry weight of 821 kg, is equipped with two huge unfoldable circular solar panels provided by NASA with a single panel diameter of 7.3 meters, due to the Trojan asteroid belt far from the sun. The detector is only 3.95 meters wide before unfolding, 7.28 meters high, 14.25 meters wide after deployment, and the effective battery panel area reaches 51 square meters. Even near the Trojan asteroid belt, where the sunlight is less than 3% strong enough to produce 500 watts of electricity, Lucy only needs 82 watts of electricity to ensure that the payload is working properly during the exploration of the asteroid.
The Lucy probe is equipped with two huge unfoldable circular solar panels provided by NASA
The probe carries a total of 3 instruments, all of which make full use of the results of existing detector technology, and the "Lucy Thermal Emission Spectrometer" derived from the "Osiris-Rex" will determine the surface temperature of the Trojan asteroid by observing the thermal infrared spectrum to help understand the physical properties of surface material. Derived from New Horizons, the Lucy Remote Reconnaissance Imager is a high-resolution panchromatic visible camera that will bring the most detailed images of the Trojan asteroid's surface after Pluto's classic "bicentric diagram" and "gourd diagram" of "The End of the World."
There is also a two-part "Lucy Ralph" from New Horizons, with the "Linear Standard Imaging Spectroscopy Array" as an infrared imaging spectrometer, and the "Multispectral Visible Imaging Camera" taking color images of the Trojan asteroid to help determine the composition of the star.
The windsurfing board is not locked and buried
03
In early 2019, United Launch Alliance successfully secured the launch contract for a total of $148.3 million, launched using the 401 configuration of the Cosmos 5 rocket.
The Cosmos 5 rocket successfully launched the Lucy probe
With the proud performance of "hundreds of shots, on time and on time", it is not surprising that the rocket won this mission. The emphasis on "punctuality" is due to the complexity of Lucy's orbital design, which requires a series of flybys to perform gravitational acceleration, which will fly over the Earth three times in October 2022, December 2024 and December 2030, which requires that the launch must take place in October.
After launch, the probe experienced two gravitational accelerations of the Earth, then went straight to the orbit of Jupiter, and flew by the first detection target - a main belt asteroid in April 2025, and during the detection process, each scientific payload will "test the bull knife" to accumulate experience for subsequent exploration.
Around 2027, the probe will reach the L4 Trojan asteroid group in jupiter orbit and detect four Trojan asteroids, including one asteroid that has just been discovered by the Hubble Space Telescope and has a diameter of only 1 km.
Subsequently, Lucy will spend 5 years to make a long "transition", from L4 to the L5 asteroid group, in 2033 to detect a binary system of 2 asteroids. At this point, after a process of up to 12 years, "Lucy" will complete the original 8 asteroid exploration mission, if the probe still has spare capacity, it can continue to select new targets and explore more unknowns for mankind.
The whole exploration program seems subtle and perfect, but the reality is always full of bumps. Shortly after "Lucy" lifted off, NASA announced that it had not received the unlock signal of the solar panel on the side of the detector, so it could not confirm whether the panel on the side was unfolded and locked in place, which laid a hidden danger for the subsequent development of the probe. But NASA insists the probe is currently operating steadily, with the power supply reaching the expected level of 18 kilowatts.
Schematic of the solar panel unfolding process of the Lucy probe
Having said that, the panel's problems still have an impact on subsequent payload boot tests and tuning, but as a mission that promises to refresh human cognition, we still hope that its journey will be smooth.
Text/ Wang Xin