It is often said that entering the orbit is not so much ascending, as it is a very fast lateral movement. So in this sense, A recent launch by aerospace startup Astra It can be considered that the vehicle just got the sequence of operations wrong.Instead of rising and burning toward the horizon, it created a Abnormally Flying sideways unusually, then finally moved towards the sky.
As you might expect, the booster did not get into orbit. But not because of lack of experimentation. In fact, the 11.6-meter (38-foot) aircraft can navigate through its unprecedented lateral maneuver and correct its flight path to a large extent, which proves the engineering strength of the Alameda, California-based company team . It is worth noting that the ground controller decided to cut off the engine after the rocket flew high enough and far enough not to endanger anyone on the ground, and finally ended the flight; until the last minute, the booster itself was still trying to reach space.
Ironically, this flight was Astra’s third attempt since its establishment in 2016, and it was the first time it was broadcast live on YouTube. If the company had not lifted their usual veil of secrecy, we might not have such wonderful high-resolution lenses, which will always be remembered as one of the most bizarre rocket accidents in history. The surrealistic image of the rocket slides out of the screen smoothly, as if it is trying to avoid the camera’s sight. This has become a meme on the Internet. It can be said that it has been exposed to more and more variety than a successful launch. Audience. As they said, there is no bad news.
Naturally, virus editing caused some problems. You don’t have to be a space expert to know that the tip of a rocket should normally rise, but considering how smooth the maneuver looks, some people even wonder if this was not intentional. Such an unusual event has received so much attention, and now seems to be the best time to take a closer look at the launch process of Astra’s latest rocket, literally, horizontally.
Perfect balance
Everyone knows that it is difficult to send a rocket into space, but unless you have read the Tsiolkovsky Rocket Equation, you may not realize the truth of this sentence. Even if all goes well, there are already many requirements, and the physics that controls chemical rockets is particularly cruel. In the simplest terms, the “rocket equation” determines how much of the rocket’s launch mass is dedicated to propellant, rather than actually carried.In the aerospace industry, this is usually expressed as a booster Payload score.
The space shuttle’s payload ratio is only about 1.5%, while the SpaceX Falcon 9’s payload ratio is slightly higher than 4%. Astra did not provide detailed specifications of their current launch vehicle, but considering how small it is and some mathematical principles, we can assume that its payload ratio does not exceed 1%. We can further estimate that the thrust-to-weight ratio (TWR) of the aircraft must be very low during lift-off.
This is exactly what we saw in the live video released on August 28. After ignition, one of the rocket’s five first-stage engines failed. This reduction in thrust makes the aircraft’s TWR very close to balance. Instead of climbing vertically, it enters a very stable hovering state. Fortunately, the engine that failed was exactly the opposite of the launch tower, which meant that the asymmetric thrust of the remaining engines moved the vehicle laterally away from the launch pad. If one of the other engines fails, the rocket is likely to hit the launcher or some other ground support equipment.
The rocket now has no structure and travels horizontally, but it is still consuming propellant at an incredible speed. About 5 seconds after the engine started, it burned enough fuel and oxidant to make the mass of the vehicle lower than the total thrust of the engine again. When TWR is positive, the vehicle begins to crawl away from the launch area, although the speed is much lower than normal. During the live broadcast, you can see the obvious confusion of the camera operators, they expect the rocket to be much higher in flight and need to pan backwards to stay in the frame.
As the rocket climbs higher and higher, it begins to look like a fairly typical launch. After about a minute of flight time, you never know how close the rocket is to being destroyed when it lifts off. Its reduced thrust and tilted ascent meant that it would never be able to enter space, but it did make a brave effort.
Just before the mission end timer hits 2:00, a surprised ground controller can be heard in the live broadcast saying that the rocket is actually approaching its nominal lower range trajectory; it seems that the sentence is destined to be the next Easter egg Kerbal Space Program.
A truly significant failure
It’s easy to look at this release and see it as a major setback for Astra. In fact, the company’s stock price plummeted by nearly 20% when it started trading on Monday morning. But although it is obviously not the ideal result, the reality is that things may get worse. On the one hand, the fact that the launch site was completely unscathed is nothing short of a miracle. In 2014, an Antares rocket exploded a few seconds after liftoffIt took nearly two years to repair the launch pad, costing about 20 million U.S. dollars.
In the end, this incident is a clear proof that no matter who handles the guidance and navigation system on this rocket, no matter what reward they get, it is worth it. An avionics package can not only maintain vertical balance when the vehicle is moving laterally, but also eventually find a way to return to its prescribed trajectory, which can only be designed by the sharpest eyes. If there is any question about whether you can make a rocket-powered Segway, it seems that the good guys at Astra have just answered this question for us.