Lunar mission "Bereshit" - analysis of the accident, announcing the launch of the development of the apparatus "Bereshit 2.0"

Late evening on April 11, 2019 became the starting point for the start of the new project - “Bereshit 2.0”, since the accident of the first private device, while trying to land on the Moon, only provoked engineers and the organization of SpaceIL.



Cosmos is cruel, and the Moon does not immediately allow itself to sit down. But with experience and modern technology, each new attempt becomes more successful.





What progress was achieved by the mission "Bereshit"?



Briefly about the mission “Bereshit”: 8 years of development, the cost of the project is $ 100 million, 200 volunteers, scientists and engineers, 47 days of flight and more than 6.5 million kilometers overcome, at the start 380 kilograms of fuel, the forced engine “LEROS 2b”, 6 on-board cameras , a magnetometer, an array of laser corner reflectors, and 1 landing attempt, in which a 150-kg apparatus with 76 kilograms of fuel (hydrazine) in tanks at high speed, having flown far away from the planned landing zone, fell onto the moon's surface.



The Bereshit spacecraft in orbit of the moon and during landing used a magnetometer and transmitted to the PMU some of the scientific data on the magnetic field of the moon.



Now Israel is the 7th country that put its spacecraft into orbit of the moon (and kept it there for 7 days).



The list of countries (their first devices are taken into account) with devices in the Moon’s orbit:



1. Luna-10, USSR, 1966;

2. Lunar Orbiter 1, USA, 1966;

3. Hagoromo, Japan, 1990;

4. SMART-1, ESA, 2005;

5. Chang'e-1, China, 2007;

6. Chandrayan-1, India, 2008;

7. Bereshit, Israel, 2019.



And yet, now Israel is the 7th country that dropped its spacecraft on the Moon (albeit in the process of landing, which went into an uncontrollable fatal fall).







It is assumed that the diameter of the formed crater after falling from 3 to 5 meters. The Bereshit device crashed into the surface of the Moon at a small angle (~ 8 °), the crater can be elongated.



The cost of the components of the unit "Bereshit" ( picture taken from here ):









What happened when the Bereshit device landed on April 11, 2019?



In fact, problems with the Bereshit device began almost immediately after the start.



February 2019:



Sunlight by the sunbeams of the position sensors of the apparatus (the sensors rendered them very sensitive to such “blinding”) may affect the orientation of the apparatus in space.



Solution: software compensation was performed to process the data from the sensors and reduce their sensitivity; additional repeated checks of new data from the sensors of the device were made.



At the preparatory stage, before performing the second engine maneuver, the onboard computer of the Bereshit device unexpectedly rebooted, and the stage of the maneuver was automatically canceled. SpaceIL and IAI engineers began to analyze the situation.

On board, there was a problem that limited the maneuverability of the device.



Solution: SpaceIL and IAI engineers eliminated the failure in the computer system of the Bereshit apparatus, now the Bereshit apparatus continues its flight to the Moon in the normal mode.



Further, SpaceIL did not announce any new problems or problems with the Bereshit device , however, before the lunar maneuvers, there was a slide in the report where there were more than one reboot / failure in the work of the BC - several and even more than engineers expected , and because of the tough space environment.



Problems and solutions that were in space (it turns out, there were many reloads of BC):







Thus, it could be expected that after 1128 hours of flight (47 days), problems with the internal components of the Bereshit device can become fatal, and their correction is impossible in case of failure of elements or their abnormal work under serious load and influence of the space environment.



Landing the device on the moon is a complex process in which the on-board computer performs a large amount of tasks: managing engine operating modes, analyzing telemetry and sensor data (position, altitude, speed, landing, etc.), adjusting the current position of the device, according to the landing path and actual coordinates, adaptive fuel consumption, data transfer using a communication system.



And if an abnormal situation occurs with one or several sensors during landing, then this moment can be compensated for automatically, if there is a backup scheme, or by restarting (reloading) the on-board computer system, if there is time for this process.



In the manual mode and in real time, the engineers at the MCC did not control the Bereshit apparatus; the on-board computer conducted the landing after the apparatus left the “point of no return”, when it only remained to perform the landing procedure, the commands of which were received earlier by the on-board computer.



But to take into account the situation and compensate for problems when several elements fail in a cascade, and then due to their failures, shutdowns of the main components of the device (engines, telemetry system, on-board computer) will begin - it is difficult for a device of this level (without redundancy of control systems ), as shown, is impossible.



What else is known about the hardware and software components of the device "Bereshit"



- one (1) engine 430N and eight (8) shunting engines 25N. Shunting engines used in landing to help the main;



- the temperature of the electronics is maintained in the range of -10 ° C to + 40 ° C. Most of the electricity is spent on heating the electronics (no cooling system);



- on-board computer one (1), not duplicated;



- the star sensor for orientation of the Bereshit apparatus is equipped with a black cone for absorbing third-party beams, however, when separating the Bereshit apparatus from satellites after launch, it turned out that the cone had become contaminated, the engineers coped with this problem, found out what angles of reflection did not occur and made adjustments to the software algorithm for processing data from the sensor (using software patches);



- there were several reboots of the computer during the flight to the moon;



- program control code, commands and work with the on-board computer - in C;



- due to the fact that the computer is only one, when you restart, all updates (patches) are erased and they need to be additionally downloaded again into the system;



- data transfer rate is low: one high resolution photo (from 8 Mpx camera) loads 40 minutes;



- DLR (German Aerospace Center) conducted testing of the landing mechanism of the Bereshit vehicle.



Team SpaceIL: Most of them are aeronautics engineers and physicists. But the IDF's satellite operations unit.



Hardware systems "Bereshit", the failure of which could lead to abnormal execution of the steps of the landing procedure and the fall:





Engine apparatus "Bereshit."



The engine of the Bereshit device is a special adapted (for the Bereshit mission, its refinement was made by shortening the nozzle and increasing thrust) a chemical rocket unit of the LEROS family (for use on satellite platforms) - a modification of LEROS 2b on hydrazine (monomethylhydrazine) with a thrust 45 kgf (441H), which is slightly more than its standard characteristics of 41.5 kgf (407H).











There is an assumption that this engine was not designed for multiple inclusions and it is not throttled, although during the mission “Bereshit” there were multiple inclusions of the main engine for several minutes, and during landing ten minutes.



The total thrust of shunting engines 8 * 25H = 200H (half of the main). That is, when the main engine is disconnected, there will be a threefold drop in thrust, which was observed during landing.



Also recorded off the engine during landing:



Doppler curve landing-fall apparatus "Bereshit", around 19:19 inhibition almost ceased:







On-board computer.







Cobham Gaisler's HiRel GR712RC processor



The main element of the on-board computer in the unit “Bereshit” uses a Gaisler HiRel GR712RC dual-core processor from Cobham.



Technologically, the chip is based on LEON SPARC and is manufactured using a unique radiation-resistant silicon technology.



The SpaceIL company became the first customer of this processor and SpaceIL engineers wrote special software for it before the actual delivery and sweep on the Bereshit device.



The GR712RC is a LEON3FT SPARC V8 dual-core processor . It can operate at a frequency of up to 125 MHz in the entire range of military frequencies. This provides up to 300 DMIPS and 250 MFLOPS peak performance. Integrates advanced interface protocols, including SpaceWire, CAN, SatCAN, UART, 1553B, Ethernet, SPI, I2C, GPIO, and others. It has high-speed interface buses for external SDRAM / SRAM / PROM / EEROM / NOR-FLASH memory. Proved radiation resistance - up to 300 krad. Low power consumption.











According to the specified data, this processor was produced using the most common commercially available technology (TowerJazz 180 nm, made in Israel), about the same as the controllers for electric kettles do. Ensuring the robustness without interfering with the technology, at the expense of circuit design and topology of elements, which costs an order of magnitude less than if the technical process were developed specifically.



The on-board computer of the Bereshit device was restarted several times before landing due to the influence of the space environment (radiation, temperature).



TT & C.



The tracking system, telemetry and transmission of control commands (TT & C - tracking, telemetry and command subsystem) used in this project, at the final stage of landing two (2!) Times "hung", although its status was "OK"



Sensors and elements of the Bereshit apparatus systems in the telemetry data window:







How the telemetry system hung:











Here is what engineers saw at the MCC during landing, according to telemetry data:



Regular landing mode:























And here the problems with the engine shutdown, the “freezing” of the telemetry data and the non-standard speed readings, which should be completely different at the calculated heights, have already begun.



































23:03 Telemetry indicator turns green. Sub State is Orientation.



25:04 Sub State changes to Braking.



25:20 "We are past the point of no return."



25:26 The Point of No Return Indicator turns black.



25:52 Vertical velocity display turns green.



28:16 Telemetry indicator is no longer green.



28:20 Telemetry indicator turns green, then is no longer green.



29.37 Distance is shown as 210 km.



29:50 Distance changes to 385 km.



30:03 Distance changes to 370 km.



30:40 Telemetry indicator is green.



30:51 Distance is 314 km.



31:33 Beresheet selfie is shown. Altitude approx 22 km ??? Telemetry is green.



31:50 Telemetry indicator is no longer green.



31:55 to 32:29 "[inaudible] kill it." "[More inaudible mission chatter] busy."



32:48 Telemetry screen is shown. Telemetry indicator is light yellow. Altitude is 14095 m. Horizontal velocity is 955.5 m / s. Vertical velocity is 24.8 m / s. Main engine is on. Horizontal velocity is light yellow. Other parameters are green, except for the telemetry indicator.



32:49 All engines are on.



32:51 All engines are off.



32:55 Main engine is on.



32:57 All engines are on.



32:59 Main engine is on. Distance is 183.8 km.



33:01 - 33:03 “IMUstein not okay.”



33:02 All engines are on.



33:05 Main engine is on.



33:07 All engines are on.



33:09 Main engine is on.



33:11 All engines are on.



33:13 Main engine is on.



33:16 All engines are on.



33:20 Telemetry indicator turns green. All engines are off. All displays remain static (no change).



33:32 Telemetry indicator is no longer green. All engines are off. All displays remain static (no change).



34:24 Telemetry indicator turns green. All engines are off, yet supposedly turn on. Vertical acceleration on the Z axis is fixed at 0.6. "We currently have a problem in one of our inertial measurement units." Vertical velocity starts to increase. Altitude continues to steadily decrease. Vertical acceleration on the Z axis becomes fixed at 0.6. Main engine probably is not on.



The telemetry indicator intermittently turns green and then turns up yellow.



34:56 Telemetry indicator is no longer green. Although all engines are shown as on, the vertical velocity continues to increase. Vertical acceleration on the Z axis fixed at 0.6. Main engine probably is not on.



36:25 - 36:33 “We’re having trouble with our main engine. We are resetting the engine. ”



36:40 Telemetry indicator is green. All engines are fixed at 0.6 m / s. Altitude is 678 meters. Horizontal and vertical velocities are 948.1 m / s and 130.1 m / s respectively.



36:44 Last telemetry data. Telemetry indicator is green. All engines appear to be on. Z axis acceleration changes to 0.7 m / s. Final altitude is 149 meters. Final horizontal and vertical velocities are 946.7 and 134.3 m / s respectively. Main engine does not appear to be operated properly.



The last 4 seconds of the life of the device according to the data center (from 678 to 149 meters reduction):



















At 19:23 the telemetry data completely ceased to arrive.



Previously, the problems started at an altitude of 14 km, the main engine shut down during the landing process, and after it was restarted it was too late — the device could not brake correctly, this problem led to a hard fall at high speed and from a height of 150 meters to the Moon.



Inertial orientation block (inertial measurement unit - IMU1, IMU2) - the nodes are duplicated.



But this is interesting, since here two blocks were used and their data were very important for the onboard computer.



Already earlier, due to the failure of such modules, there were accidents - as with the Sciaparelli apparatus on Mars in 2016.



It turned out that the fatal error in the work of the Schiaparelli software was due to problems in the work of the “inertia meter” (IMU), a device that measures the rotation speed of the module around its axis.



The data from this device , as the engineers explain, was taken into account when processing data on the flight altitude coming from the Schiaparelli radar. At one point, the IMU failed to function, as a result of which it “measured” the abnormally high speed of rotation of the Lender, which went beyond the limits of permissible values. Such failures are the norm in the work of inertial sensors, and usually to suppress them, scientists "smooth out" the signal and compare the data for the current moment with the results obtained at previous points in time.



But in this case, the IMU transmitted data to the Schiaparelli main computer for an unexpectedly long time, for a second, which “deceived” the software of the module and made him consider these measurements to be real data, and not an anomaly. Incorrect values ​​were taken into account when calculating the module height, as a result of which the Schiaparelli on-board computer received negative height values.



The module considered that it was not even on the surface of Mars, but beneath it, which made him, at a height of 3.7 km, initiate the final stage of the landing procedure, separate the parachutes and turn off the engines.



In the device "Bereshit" used such a module IMU: STIM300 .







This module does not have a high level radiation protection characteristic, so the use of such devices on the Moon may be even more thoughtful by SpaceIL engineers further in new missions.



Since there was a statement from SpaceIL after the accident: “Problem in one of Beresheet’s inertial measurement units. Ground controllers lost telemetry. ”



Did the module (or both modules) of the Bereshit IMU give out incorrect data (including the measurement of angular and linear accelerations it became impossible) for the on-board computer and for what reason it is still being investigated by SpaceIL engineers



However, for the time being it is clear that the Bereshit apparatus had a technical failure in the operation of one of the components, which led to the shutdown of the engines, which did not allow the apparatus to reduce the rate of descent to the lunar surface.



When the engines were restarted, they were no longer able to complete braking, it turned out that the speed of the vehicle was too high, and the height to the surface of the moon was critically reduced, and a destructive collision occurred.







The last photo from the Bereshit device also baffles a bit.Since it is visible on the lunar surface of 1000 km from the planned landing zone in the Sea of ​​Clarity.



The last frame (officially published) from the Bereshit apparatus (from a height of 8 km):







Thus, it will be very difficult to find at least something from the Bereshit apparatus, since the search area is very extensive:







Although it is a little clear where to look (200 km to the landing zone "Apollo 11"):











NASA plans to survey the area of ​​the Bereshit apparatus with the help of an LRO probe, in the hope that the elements of the array of laser corner reflectors have not collapsed and will be located on the lunar surface.



Reflectors were fixed on the upper part of the apparatus and, if it fell, could bounce, fly apart, roll over and dig in the lunar soil. But even if only part of the reflector is available to reflect the light pulse - this will be fixed by the LRO.



The LRO laser altimeter (NASA lunar orbital probe), designed to compile an altitude map, will send laser light pulses to the corner reflector at the site of the Bereshit apparatus, and then measure how long the light takes to go back.



Using this technique, NASA and SpaceIL engineers plan to be able to locate the remains of the Bereshit vehicle.







Although it’s also interesting here, in SpaceIL there are still photos of the fall, but they don’t publish them:



- Is this the last photo received from Beresheet? When exactly was it taken? I ask because the Hypatia crater is much more southern than the planned landing site.



- It is not taken. Have for We one's picture taken That WAS closer to landing But has not Been confirmed to the BE Be published yet . I assume that it will be published soon.



What will happen next with the mission "Bereshit"?



The development of a new space project, Bereshit 2.0, was announced .







Israeli Prime Minister Benjamin Netanyahu promised that the state would take part in the second attempt to send an automatic station to the Moon.



“We're going to launch Bereshit-2.” The State of Israel participated in the launch of the first spacecraft and will participate in the launch of the second. I hope that this time everything goes well. In this case, we will truly become the fourth country in the world to land on the moon, ”Netanyahu said at a government meeting.



It is planned that the project "Bereshit 2.0" will be more serious and costly (compared to the first), but still be private.







SpaceIL will also take over the main management of the new project “Bereshit 2.0” and will also remain a non-profit organization.



The planned implementation period of the project "Bereshit 2.0": 2-3 years.



It's great when the country, engineers and people do not stop believing in victory.







No dream is beyond your reach, if you truly want it!



And for dessert :



Lego model of Beresheet