The spacecraft in Genesis was captured by the moon's gravity; Preparing for a busy week of maneuvers until landing

The managers of the operation describe the process of capturing the moon and what is going to happen in the coming week

The spaceship in Genesis was captured by the moon's gravity. This was learned after a tense evening in which the spacecraft's engines were turned on for about seven and a half minutes, about 50 kg of fuel was burned, and the spacecraft's speed slowed down.

The engineering team of SpaceIL and the Aerospace Industry performed the most decisive maneuver so far in the spacecraft's journey to the moon - "capturing the moon" this evening (Thursday) at 17:17. The maneuver allowed the spacecraft to be captured by the moon's gravity and thus begin to circle it and with it the Earth.
At 17:18 the spacecraft's engines started to operate for about 6 minutes and slowed down by about 1000 km/h from a speed of 8,500 km/h to a speed of 7,500 km/h relative to the moon at the speed of Genesis. The maneuver was performed when there is full communication with the spacecraft and the indications received in the control room in real time correspond to the planned route. In the coming week, which is expected to be an intense week in engineering activity, a large number of maneuvers will take place, from an elliptical orbit to a circular orbit at an altitude of 200 km above the moon, the purpose of which is to lower the altitude and reach the optimal point for the autonomous landing of the spacecraft in the "Sea of ​​Calm" on 11/4 in the evening.
The maneuver put the spacecraft into an elliptical orbit around the moon where the closest point (Perilona) is about 500 km from the moon and the farthest point (Apollona) is about 10,000 km. Unlike the long orbits around the Earth, the first orbits around the moon will last about 14 hours and towards the landing the entire orbit around the moon will last only about two hours.
At the beginning of the week, the spacecraft reached for the last time the closest point to the ball in Israel in the last lap around it - only 1,700 km and from there it continued on its way to the meeting point with the moon at a range of 400 thousand km.

At a press conference that took place before the critical operation, the director of the space plant of the aerospace industry, Ofer Doron, described the process of capturing the moon: "We are in orbit around the Earth, which is 420 thousand km high. At the top we are very slow. We are sailing slowly. From tonight we are no longer subject to the gravity of the earth, but are influenced by the gravity of the moon."

"We are moving slowly and the moon behind us is coming fast. It begins to pull us towards it, because it is closer and the spaceship makes a U-turn and starts running towards the moon and accelerates more and more and enters a circle above the moon, more or less between the poles of the moon. It does this so fast that if we don't slow it down it will continue to fly around the moon and continue to travel further and become a body that is affected by the sun's gravity, and we kind of don't want that to happen. We are going to hit the brakes for six minutes and reduce the spacecraft's speed by a thousand kilometers per hour - 324 meters per second. from 8,500 to 7,500 km/h. Speed ​​relative to the moon.”

"Further down the road, during the next week we need to bring the spacecraft to a suitable orbit for landing. We will inject it into an orbit of 400 kilometers high (Perilona) and the far part of the moon (Apollo) is about 10,000 km, the coffee takes 14 hours. On Sunday we will change speed again, we will brake again and bring the Apollon down to 750 kilometers, the next morning we will bring it down to 400 kilometers, and then we will do two maneuvers that will bring us down to 200 by 200 kilometers. On Wednesday, a strong brake will be applied and it will be lowered to a height of 15 km above the ground, until it reaches the landing itself. The landing process is scheduled for Thursday, April 11 at around 23:00 p.m., although the time is still not final and depends on the events that will take place during the coming week."

The CEO of SpaceIL, Dr. Ido Antavi, used the last opportunity for a media event before the landing to update on what has happened on the Beresheet spacecraft since its launch on March 22.

"First, the launch was successful and on time. It happens that there are many delays in launches. The launcher placed us in the orbit we wanted, at an altitude of 70 thousand km and all the systems functioned as required, except for the star tracker, so all in all, a successful launch. Six weeks we have been in space, we have done all our maneuvers, except for the first maneuver, all the other maneuvers were successful despite the same problem with the star tracker. Our fuel consumption as required. We have an excellent relationship with the spacecraft and when we need it we call it. We have a close relationship with the ground stations, the accuracy is a little less than what is required, but we are improving it."

"The star tracker is a critical means of navigation. We got a bigger dazzle than we expected. Our engineers managed to work around this glitch. We had to perform more complex maneuvers. It remains to be seen how the moon will affect that star tracker."

"At the same time, we had several RESET computer reboot events, which were repeated throughout the entire mission. They were caused by the space environment - radiation, charged particles. It is impossible to completely prevent a reboot, and you have to manage despite the reboots. Here, too, the engineers did a good job. We made a number of software patches so that it can continue to function well and reduce the impact of reboots."
Antavi added: "After six weeks in space, it seems that we have succeeded in passing another critical stage and being captured by the moon's gravity. This is another significant achievement that the engineering team was able to achieve, while proving professionalism, determination and creativity in solving and bypassing faults. We still have a long way to go until landing, but I am convinced that our teams will be able to complete the mission - to land the first Israeli spacecraft on the moon and bring pride to all of us"
Nimrod Shafer, CEO of the Aerospace Industry: "After a challenging journey, tonight we broke another Israeli record and became the seventh country to orbit the moon. "Bereshit", even before it was launched into space, is a national success story that represents our groundbreaking technological capabilities. Tonight we reached new heights again. In the coming week, the talented engineering team will work around the clock to bring us to the historic moment on 11.4/XNUMX- "Bereshit" and good luck!"

The challenges in landing:

Before the landing, the exact landing area will be determined around the calm sea. There are several considerations before landing, including a flat site with a diameter of about 30 kilometers, so as not to catch many craters and rocks. We also want to land on the moon at a precise time, before the lunar surface heats up, and it heats up to 130-140 degrees at noon on a lunar day (a day on the moon lasts two weeks). That's why we want to land at a relatively early hour when the sun is not yet warm. We want to have good communication with the spacecraft, and we have to remember that we are arriving at a high speed of 6,000 km/h. We go in to land on a runway at an altitude of 25 km, then we give her the orders. The sensors that report speed and height above the surface of the moon transmit their data to the control software. The information control software calculates what it needs to do and what commands it needs to give to the engines to brake the spacecraft. In the first stage, the spacecraft's small engines rotate it so that the engine faces forward, so that the engine will face the direction of the spacecraft and its activation will cause braking. We also want to direct the spacecraft so that fuel reaches the engines. At this stage there is still no gravity, so you have to rotate the spacecraft to achieve this."

"As soon as we have rotated the spacecraft and enabled the operation of the main engine, we will activate the main engine and lower the spacecraft speed to zero. At a height of five kilometers it will operate a laser-based altimeter and speedometer. It will continue to glide and at an altitude of one kilometer we aim for the horizontal speed of the spacecraft relative to the moon to be zero and the spacecraft will transition to a vertical landing. Using the main engine we can control the speed of the spacecraft and we hope to reach a height of 5 meters above the surface of the moon at zero speed. We will turn off the spacecraft's engines and it will free fall on the surface of the moon, you have to remember that the gravitational force on the moon is one-sixth of the gravitational force on Earth, so it is equivalent to falling from a height of 80 centimeters on Earth. The spaceship's legs know how to manage it."

However, Antabi warned that there are many more risks until the landing and in the landing process itself: "There are still risks along the way, starting with a computer operation or any other action that will cause the engine to stop working, without the main engine it is impossible to brake the spacecraft. We are making a blind landing. Even if we reach the surface safely, it may land on a rock, or capsize. There are no shortage of risks. I remind you that our spacecraft has low redundancy, so damage to one of the components could damage the entire mission. If the landing sensor stops working for some reason, there is no one to measure the height of the spacecraft above the ground and the speed of the spacecraft. This is also a failure mechanism. We all fully understand that this is the first time this spacecraft has landed on the moon. We never tested it, we never tried it. All the experiments and tests we did were partial. I want to mention that the entire landing will be autonomous. For 25 minutes we will not be able to send any command and we will not be able to fix anything on the spacecraft during those minutes."

Cheers from all over the world

SPACEIL Chairman Maurice Kahan who greeted at the beginning of the event said: "The way we got here is a miracle. We owe it to the people who actually worked, an amazing team of people in the aerospace industry and SPACEIL. They brought us here. In Israel they are very excited about the successes of the spacecraft. They were also enthusiastic in America. When I was at the AIPAC conference last week, there were 20 people there and they stood and applauded. It was not for me but for the State of Israel, our achievement, our audacity. They are with us. We received support from all over the world. NASA recognized what we were doing. We are pioneers in something in space, showing that a small country can do a great job. Today is a critical moment. I am sure we will succeed (in landing). It captures the imagination, we've done something big, I'm crossing my fingers, and I don't believe in superstitions. I'm sure we will succeed."

More of the topic in Hayadan:

"We have reached a parking orbit around the moon"

Recording of the live broadcast of the moon capture event, April 4, 2019, from the SpaceIL YouTube channel