What do Japanese ultra -small spacecraft "OMOTENASHI" and "EQUUULEUS" fly on the moon?

ARTEMIS I's mission diagram.Launch orion and return to the earth (c) NASA

When the launch of the asteroid spacecraft "Hayabusa 2", Japan used the surplus of the rocket to share the ultra -small spacecraft "Procyon".ARTEMIS I also provides a launch opportunity for a 6U size (10 × 20 × 30cm) cube thut.Initially, the selection was progressing only in the United States, but the international partner was heard because of the space.

The condition is to include technology and science missions that promote manned exploration.JAXA was contacted in August 2015, and although only two months had been closed, Omotenashi and Equuleus were selected, proposing multiple missions.At that time, it was scheduled to launch in 2018, and the development period was only about a year and a half, and the development was promoted in JAXA.

ARTEMIS I is equipped with a total of 10 spacecraft, in addition to two Japanese aircraft, seven US and one Italian aircraft.Originally, 13 aircraft were planned, but three were not in time.

These shared spacecraft are installed in the adapter between the spaceship and the upper rocket.After the Orion is put into the monthly transition orbit, it is separated.The SLS upper row passes through the moon and is dumped into a planetary space, but during this time the separation timing can be freely selected by the spacecraft side.The two aircraft in Japan are planning to separate early, near the Van Allen belt.

The launch date is still known only after February 12, 2022, and the official date and time will be decided after the rehearsal test scheduled to be held in early January of the same year.Of the two aircraft, Omotenashi is planning to land the moon, but if the launch is not significantly delayed, it is likely that it will be Japan's first lunar landing.It is also noteworthy in that regard.

Can you realize the world's "smallest" lunar landing?

"Omotenashi" is a spacecraft aimed at demonstrating innovative lunar landing technology.According to Mr. Kiaki Hashimoto (Professor of the JAXA Space Science Research Institute for Space Equipment, there are many missions in which other phase riding spaces have already been selected, so we avoid competition.He suggested that there was no other landing.

The biggest feature is to challenge the world's first technology, a small cube -sut -class spacecraft, to land the moon.Usually, no matter how small, landing machines are about 100 kg.However, if it can be realized with a cube trap, the cost will drop in an order of magnitude.Mr. Hashimoto hopes that "universities, small and medium -sized businesses, and individuals will be possible. The threshold will fall and various ideas will come out."

Also, if the cost goes down, you can launch a lot and find out various places on the moon.A large plan can also be a complementary role.

However, it is difficult to miniaturize the lunar landing because, unlike Mars, there is no atmosphere, so it is not possible to use aerodynamic deceleration methods such as parachute.In order to decelerate, a large thrust of a rocket will inevitably need.

Basically, to make the spacecraft smaller, it is better to reduce the parts and components.However, there are some propulsion systems, such as valves, and some of them cannot be less than a certain level, and the structure efficiency is steadily deteriorating, so there is a limit to miniaturization.OMOTENASHI is the challenge of how much it can be minimized.

Liquid rockets are highly performance, but they are not suitable for smaller because they have a complicated structure.In effect, there is only a solid rocket, and this time we have developed an ultra -small solid rocket motor with a diameter of 11 cm.However, it is still impossible to land the total weight of the spacecraft, so it is dumped except for the landing portion during ignition.

In general, "landing" refers to soft landing (soft landing), which lowers the ground speed to zero by reverse injection.On the other hand, there are uncontrolled hardland dating, but rather the image of "falling" and "collision" rather than landing.Omotenashi aims for a semi -hardware, which can be said to be in the middle.

The precise control of the thrust is essential for soft landing, but the solid rocket has no choice but to wait for it to burn out.Since the errors in the deceleration amount (ΔV) inevitably increase, the only remaining speed is tolerated in order to make sure to land.

In the case of OMOTENASHI, this speed is about 50m (180 km / h) per second.Equipped with aluminum crushable materials under the landing part to withstand the impact of the crash.By crushing and absorbing the impact, the impact on the landing part was reduced to about 8,000g.The inside of the device in the landing part is filled with epoxy to eliminate gaps, and it is designed that can withstand more than 10,000g.

Initially, we planned to use an airbag to absorb the shock from the upper side, but it was decided that it would collide only from the bottom, so it would not be necessary to expand.However, since this airbag is also used as an antenna, it is only expanded.The landing part is equipped with an amateur radio transmitter.If this radio wave can be received, it will be a successful landing confirmation.

I would like to see the video on the moon directly, but I could not put the camera even in the landing part.However, it is said that it is installed on the main unit, so it will be implemented on the earth.

Omotenashi is the main body (OM) 7.6kg, solid rocket motor (RM) 4.3kg, landing club (SP) 0.The composition is 7kg, the total weight is 12.6kg.The main unit is also equipped with a gas jet propulsion system to turn the spacecraft toward the monthly shock.In order to stabilize the solid rocket motor, use this gas jet before ignition to rotate the main unit at high speed.

OMOTENASHI operation

The above is an engineering mission, but Omotenashi also measures the radiation environment as a scientific mission.For this reason, it is equipped with a remodeled portable dose meter for consumer goods.Although the accuracy is limited due to the ultra -small size, observation opportunities outside the earth magnetic range are valuable.In the future, it is expected that if it is installed on many ultra -small spacecraft, it can contribute to the accumulation of data.

Aim for the lagrange point with 1 liter of water

"Equuleus" is a spacecraft that demonstrates efficient orbital control technology in the sun-earth-moon.Ryu Funase (Professor of the JAXA Space Science Research Interior Sciences, and Associate Professor of Aertrae Engineering, Graduate School of Engineering, the University of Tokyo) is also a developer of Procyon and a very small deep space spacecraft.This is the second machine.

The destination of Equuleus is the lagrange point L2 on the other side of the moon from the earth.The lagrange point is a place where the gravity of the earth and the moon and the centrifugal force are well balanced, and it is known that there are five places.Because it can be located in that place without using much fuel, it is expected to be a place to install Fuka Space Port, and can be used as a relay point to Mars to the moon or to Mars.

Equuleus is the first cube thut to the Earth-Moon Lagrange Point L2 (EML2).Since the cube thut cannot be equipped with much fuel, the orbit control ability is extremely limited.However, by using the gravity of the sun and the moon, it requires a long flight period of about six months to a year, but can also reach L2 with cube thuts.

After launching, the track heading to L2 is very complicated to carry out the moon swing by several times.However, this can further reduce fuel consumption rather than directly to L2.The necessary control (ΔV) is only a few 10m/s, which can be achieved with a cube thut.

The weight of Equuleus is 10.5kg.The big feature is water (1).It is to be equipped with a resist jet with 22kg).Water is harmless, or it is safe enough to drink, so it has the advantage of being very advantageous in the safety screening of the spacecraft.In addition, water may be available on the moon, and in the future it is possible to procure water in space and use it to go further.

In the future, the progress of the ARTEMIS plan is expected to further increase the opportunity for the moon.If you use orbital control technology, if you can reach a small amount of fuel, the degree of freedom of ultra -small missions in the future will be improved and various scientific results will be obtained.What we are aiming for in Equuleus is to prove the possibility.

Equuleus also plans three scientific missions.

The "Earth Magnetic Space Plasma Image" (Phoenix) uses an extreme ultraviolet camera installed.Take a picture of the entire magnetic sphere, taking advantage of being far from the earth.It is expected to deepen the understanding of the radiation environment around the earth and complement the observation of JAXA's Geosus Exploration satellite "Arase" (ERG).

The "lunar collision flashing observation" (Delphinus) aims to observe the flash emitted by a meteorite that collides on the moon with a high -speed camera with visible light.From the L2, it is possible to observe long -time continuous observation without being disturbed by the global light.As a result, the size and frequency of meteorites falling on the moon can be understood, and the risk evaluation of the lunar manned activities can be evaluated.

In the "Earth-Moon Dust Detection" (Cloth), the space around the earth and the moon examines how much fine particles (space dust) are drifting.For this reason, a thin film -like dust detection sensor is embedded in a golden MLI (multilayer insulation material) that covers the spacecraft.As a result, a large observation area was realized while the cubeat.