≡ Menu
DeemOcean header image

*2019/7/8

Before ALL:

Hello folks, since the summer began, I have to say a project I have planed for a long time should get into its path now. And it is a serial, so I will update the lastest processes as I do.

Basically, the goal is to build a fully fictional rocket which has a Thrust Vector Control(TVC) which allows the rocket could control the thrust direction stay toward the earth, and a panel with velocity sensors, direction sensors on so the SCM could compute.

Then, I would add more functions to the rocket, such as muti-thrusts. So finally allow the rocket to get into space(stratosphere?).

OK, there are few steps I need to do in order to make this goal comes true.

Stage One, build a TVC

Stage Two, build a control panel and write software

Stage Three, build a rocket as a whole

Then, test, test, test…

If I can make it, then add more functions and let it go the space.

Now, everything starts here.

Stage One: Build a TVC

Prototype One

Prototype 1:

The video was made a long time ago, so there are many things not been added compared to now I, but the idea is the same. Basically, I 3D-printed a model to physically exam my idea, and know I find there are two main problems need me to fix.

  1. I need grooves and rooms to fit my two servo motors
  2. The outside ring needs to control the inner ring but not directly connect the central, otherwise, the move of one axis would affect the other one, simply to say, they will be stuck.

*2019/7/28

The first “usable” TVC is done for building!

But there are still a lot of problems

  1. the size of the inner ring is too big
  2. the total design is not compact enough

*2019/8/1

After Serval models failed, the usable prototype is coming!

*testing platform is done!

Platform

*9/3/2019

I find the problem is, when I connect the rx tx ports, the board would just not working, ok, so I begin to use soft serial pin to 6 and 7. Then I find this is caused by the Arduino board Uno itself, so I change it.

Loading Likes...
{ 0 comments }

What?

随着Minecraft的多年发展与版本迭代,现在终于可以分为三大派:

1.基岩版(XBOX,WIN10 UWP, 手机)

2.JAVA版(也就是之前电脑上玩的那种)

3.网易版(辣鸡)

基岩版(BedRock)是从PE手机版脱出的版本,以前的版本总是和JAVA版大步脱节,可现在已经平头齐步走了。个人非常看好BR版,因为其平台整合的很不错,各个设备都可以玩,不论是个人联机还是教育应用都很有优势,未来开发者社区会倾倒更多资源。

Why?

这里可能有人要问了,既然已经有了领域了,为什么还有自己开基岩版服务器?

首先,领域服延迟高,其次,对多人支持不是很好,最高也就10个人,也不便宜。

最后客制化程度也很低。

How?

这里可爱的开发者团队已经开发出了基岩版服务器包(Alpha)所以只要按照我这里的步骤一步步来,在5分钟内就能配置好属于你的基岩版Minecraft服务器

服务器的选择:我推荐阿里云和腾讯云,阿里云不差钱的就搞吧,腾讯云还没试,但听说不错。

1.去阿里云(https://chuangke.aliyun.com/invite?userCode=z66uogjh)(吃我邀请码得优惠)买一台ECS服务器,最低配置就可以了,位置选靠近你地理位置的地方,系统注意了:要选Ubuntu 18.04 及以上的,第一次建议用按量付费试试水

配置

2.这样你的服务器算是开好了,点管理,左上角找到“重置实例密码”来设定密码

正常开启

3.因为我们需要19132端口来连接服务器,所以必须在安全组中添加

在本ECS云服务器实例中,点击 本实例安全组-配置规则-添加安全组规则 在入方向(出方向默认全端口开放)添加两条端口范围为”19132“授权对象为“0.0.0.0/0”的规则(一条为TCP,一条为UDP)

安全组策略

4.得到 public key:还记得之前我们设置过密码嘛?因为新版本的Xshell需要密匙文件才让你登录,所以我们这边再下载一下这个文件(妥善保管,不会让你下第二次的)在网络与安全-密匙对 中创建密匙,名字随意,把.pem文件保存. 然后点绑定密匙,将你的服务器绑定此密匙 然后点重启

key

5. 现在我们需要一个工具来连接这台服务器,别人喜欢用Putty,但我更爱Xshell

好啦,我白给你们这个工具吧:http://gofile.me/4hSto/2396fO9FW

在控制台找到服务器的公网IP,复制下来

打开Xshell, 选择New,新建一个连接, Name随意,Host就填公网IP. 默认用户名root之后就点Yes. 之后会要求Public key 这边选择一下文件所在位置,因为阿里云对key没加密,就不用写密码. 然后你会看到连接的窗口灯变绿,表示连接成功.

这里我可以用password因为我之前已经用了public key

成功连接

这边对Xshell做个小设置, 以免无法按退格: 点 File-Properties-Keyboard, 把两个ASCII 127点上

keyboard设置

6.下面来配置服务器

首先输入sudo apt-get update回车检查一下更新,不然坑爹阿里云没法让你下解压指令

1.输入apt install unzip回车下载解压命令

2.输入mkdir mc回车来创建名为”mc”的文件夹

3.输入cd /root/mc回车 进入此文件夹

-到网址为( https://www.minecraft.net/en-us/download/server/bedrock/ )在右边UBUNTU部分同意下条款, 鼠标右击复制下载链接,得到(https://minecraft.azureedge.net/bin-linux/bedrock-server-目前版本.zip)

4.输入wget https://minecraft.azureedge.net/bin-linux/bedrock-server-目前版本.zip回车, 下载服务器安装包

5.输入unzip bedrock-server-目前版本.zip回车, 解压

6.输入LD_LIBRARY_PATH=. ./bedrock_server回车 开启服务器 并进入服务器后台

大功告成!!:现在去客户端-服务器 中输入公网IP就可以进入了

(在后台输入 stop回车 来关闭后台)

Advanced:

因为要保持服务器后台时终在线, 我们要装载Screen程序

输入 apt-get install screen回车 装载程序

启动BR服务器之前先输入 screen -S mc回车 启动screen

再cd /root/mc回车 进入文件夹

最后 LD_LIBRARY_PATH=. ./bedrock_server回车 启动服务器

这样下次输入screen -ls 查看正在运行的程序 前面有几个数字

screen -r [那几个数字] 恢复窗口

screen -ls->找到数字->打开窗口

*先写到这里, 之后写怎么把地图迁移进服务器

我自己建和基友玩的服务器:[49.234.17.116] 大家可以感受一下

相信会看我文章的人非熊人

Deemo

Loading Likes...
{ 0 comments }

PS:IT’S NOT A RESEARCH PAPER

Abstract

This paper begins with the Messier 42 nebula, talking about how different color lights form due to the electron transport in Bohr’s model. How these lights are absorbed by gas and form the absorption spectrum, then how these lights are captured by sensors with the explanation between CCD and CMOS sensors. The history of spectrometer also includes plus the motivation and the reason why people are keeping doing that.

Key Words: Messier 42, Spectrum, Bohr Model, Sensor, Photoelectric effect, Spectrometer, Wavelength, Energy transform, Frequency, Coulomb’s equation

Introduction

When we were just children, sometimes laying on a green field at night the light pollution is not that bad. People lie in the starlight, and the huge Milky Way fills all of the eyesight. Surely, it is night, but when your eyes adapt to the dim, the elegant shining beauty would amaze you, indeed. Sometimes people would notice there are something different lie on the sky, something bigger with different colors. After that people who are curious about that seek for answers, Finally, they found that is called “nebula”.

The “M42”

            M42 or the Orion Nebula, mostly the most popular object in the Messier objects table. It is 1,344 ± 20 light years away(Bringmann, 2017). M42 is a diffuse nebula, which means it is formed ionized gases and diffuse lights with different wavelengths. Every day, there are stars forming, M42 is the closest factory of star from the planet Earth

Figure 1 The M42 Nebula From Francesco Battistella(2017)

This paper going introduce and explain the theory of how these colors were formed, how people transform light to digit, and the way people identify chemicals from light, plus its history, and why we do it with the foreword of M42.

Excitation and emission spectra

Light is an electromagnetic wave, it could transport energy, and because of its wave-particle duality, we can say photons have energy inside. In the Bohr Model, it could be easier to explain the whole thing because it is very clear without talking about the probability wave function or The Heisenberg Uncertainty.

Figure 2 Bohr Model and light (n.d.). Retrieved June 4, 2019

As the diagram shows left, when an electron absorbs energy it would be excited, and goes outside from its ground state orbit, and it goes back to inside orbits when they release energy. The different colors of the light release directly connect to the difference of energy because the difference of colors is the result of diverse of the wavelengths, and energy relates to the frequency of the wave follows:E=hf

Put these two into the common equation:v=f\lambda  since the velocity just equal to the speed of light, which is a constant, higher frequency result in low wavelength, vice versa. So when there is an inside orbit which contain more energy because of the Coulomb’s equation: \int{F=\int\frac{1}{4\pi\varepsilon_0}\cdot\frac{q_1q_2}{r^2}dr}=U=-W=KE=\frac{1}{4\pi\varepsilon_0}\cdot\frac{q_1q_2}{r}

Figure 3 Wavelength, Frequency, Spectrum and Energy From Errante, F.

As r gets smaller, the energy gets higher, so the inner orbit emits light with higher energy, which means it is in higher frequency and low wavelength result in more red light.

The forming of three main colors

There are three main colors the M42 nebula has: Red, Blue-violet, and Green.

Red light is the result of H- radiation, mainly, it talks about Hydrogen atom in Bohr’s model, the electron jump from n=3 orbit to n=2 orbit, and result in long wavelength of 656.28 nm(H-alpha Emission, 2013) which is red.

Blue-violet light is the result of massive O-Class stars radiation at the core of the nebula. By Harvard spectral classification, stars are classified to O B A F G K M from high temperature to low temperature. There is a pithy formula: “Oh Boy! A Fine Girl Kiss Me” Since O-class is hot, which means it has high energy, so O-class has high frequency and short wavelength, result in Blue-violet light.

Figure 4 Star classes and wavelength from Pickles, A. J. (1998)

Green used to be mysterious in the early 20th century, because there is no known spectral lines could explain that, people even think they discovered a new element. However, by the developing of modern physics, people found the green hue is caused by the low probability transition in doubly ionized oxygen, that only could happen in the lab, but still possible happen in deep space wherein extreme condition.

Photoelectric effect: How to get a photo of a deep space object

We all know the camera could take photos, but how? Why light could be transformed to digit version, that is the contribution of the Photoelectric effect. Einstein gave the mathematical explanation for it. Mainly, if a photon carries enough energy, it could let the metal emit an electron carries with same amount kinetic energy: KE=\frac{1}{2}mv^2

Figure 5 Axiom of Photoelectric effect From Simple Science (2019)

Sensor Mechanism: CCD and CMOS

The sensor is where the camera accepts lights, and the place photoelectric happens. There are two main kinds of sensor exist in the market: CCD(Charge-coupled Device) and CMOS(Complementary Metal Oxide Semiconductor). The difference between these two main in the way they collecting voltage signals.

Figure 6 CCD and CMOS From Stefano

From Figure 6, each block is a pixel that the photoelectric effect happens, when there is a photo hit the pad, one electron would go out and create a voltage signal, the difference between CCD and CMOS is shows up on their signal processing mechanism. Each pixel of CCD only transform photo to electron signal then process line by line, but each pixel of CMOS could process independently.

In Astrophotography, people more like to use CCD because it would produce less noise and record faster. Heat is the main cause of useless data pixel because the heat would mess up the voltage signal, since CMOS process data on every pixel it would cause huge heat during a long time capturing which is very common in astrophotography, but it is much better on CCD because of it process data line by line. However, to minimize the noise, some people would cool down their sensor, so there is something called cooled CCD, people cool their sensors (normally 253K) to prevent noise as possible as they can.

Spectrometer: Way to identify the chemical by its emitted light

Since the different color of light it the result of different elements jump orbitals, we could inversely use this property to identify the element combination of one object. Then, the spectrometer is invented. The grating spectrometer has the clearest mechanism with the cheap prize. It could separate one combined light source to spectrum distribution just like how Figure 7 shows.

Figure 7 Spectrometer’s Mechanism From Spectrometer(WIKI).

When a continuous light goes through a cloud, most of the spectrum would not be absorbed, but if the cloud meets the light with a certain spectrum which has the energy just enough to let its atom jump excited, the cloud would absorb it. So when people on earth observe it, they would find there are some black gaps in the continuous spectrum.

Figure 8 Spectrum’s absorption From Anthony(2013)
Figure 9 Spectrum’s absorption From Anthony(2013)

Take our star as an example, it is a G-class star with yellow looking. The black lines called Fraunhofer lines. Here in figure 9, for example, D-line represent element sodium, G-line is iron and calcium, C-line is H\\alpha…etc.

History of Spectrometer

            Newton seems to be the first one who builds a spectrometer, but he did not use that to build some vital theory theories.

Figure 10 Spectrometer used by Kirchhoff and Bunsen From History of spectroscopy(2019)

Bunsen invented a better flame source called Bunsen’s burner, now is common in labs and Kirchhoff designed the rest of it. Later, when Kirchhoff used this spectrometer to observe the sun, he found there are several black lines with different brightness, he guesses that might cause by different elements, then he uses some flames made by different sources to prove this hypothesis, and he finds he was right. After proven his hypothesis, he graphed 570 lines to indicate different elements.

The reason why we doing this

Using spectrometer could help us discover what made the early universe, and how the universe evolved because the nebula is the birth room of stars, it has a similar condition like the early universe

    To get a better image of deep space target, know their spectrum is very important because people could choose a more suitable filter to cut off other disturbing spectra to improve the image quality.

    And the mountain is there, a human being must climb it or disappear in inner dispute history.

Conclusion

            M42 is a very beautiful nebula which is the closest star birth room, the light goes through the gas cloud be to absorb some with a certain wavelength, comes to earth with absorption spectrum. The light is captured by sensors(mostly CCDs), because of the photoelectric effect, it is transformed to a voltage signal, finally become digit data, processed by computer become a gorgeous image. Knowing that helps people know more about the universe and how it formed, people use this information to take a better photo by selecting more suitable filters. Human being knows the world around it a little more, exited their fundamental curiosity, which finally becomes the reason people come out of the earth but not root on it.

Reference

Bringmann, T., Conrad, J., Cornell, J. M., Dal, L. A., Edsjö, J., Farmer, B., … & Scott, P. (2017). DarkBit: a GAMBIT module for computing dark matter observables and likelihoods. The European Physical Journal C, 77(12), 831.

F. (n.d.). Retrieved from https://apod.nasa.gov/apod/ap171129.html

. A stellar spectral flux library: 1150–25000 Å. Publications of the Astronomical Society of the Pacific, 110(749), 863.

Errante, F. (n.d.). Energy and radiation wavelength. Retrieved June 5, 2019, from https://www.radiondistics.altervista.org/frequency_wavelength_energy_radiation_calculator.htm

(n.d.). Retrieved June 2, 2019, from, https://wps.prenhall.com/wps/media/objects/476/488316/ch09.html

H-alpha Emission. (2013, May 08). Retrieved June 5, 2019, from https://ismlandmarks.wordpress.com/h-alpha-emission/

Stefano, M. (n.d.). . Retrieved June 5, 2019, from http://meroli.web.cern.ch/lecture_cmos_vs_ccd_pixel_sensor.html

Anthony, S. (2013, October 02). Every color of the Sun’s rainbow: Why are there so many missing? Retrieved June 5, 2019, from https://www.extremetech.com/extreme/167878-every-color-of-the-suns-rainbow-why-are-there-so-many-missing

Spectrometer. (n.d.). Retrieved June 5, 2019, from https://zh.wikipedia.org/wiki/Spectrometer#/media/File:Spectrometer_schematic.gif

History of spectroscopy. (2019, March 04). Retrieved June 5, 2019, from https://en.wikipedia.org/wiki/History_of_spectroscopy#/media/File:Kirchhoffs_first_spectroscope.jpg

Loading Likes...
{ 0 comments }

“The Ring”

At the wide, white house, the “master” dressed in black, stands upon the platform. “Let’s celebrate the coming of our friends, shall we?” he says to the children before him. He is their father, but not by blood. The children, dressed in white, reply “yes” one by one, with planned perfect meticulous smiles.

“Sorry, sir, but what are we celebrating?”, the youngest little “stander,” said.

The “master” askance at him with unknown mean. Saying: “Oh, you people do not hear the history yet” “Surely, you must familiar with the story before the Cold War, because that’s the thing people want to tell”

“Why?”

“Because that is the period of good.”

“How bad after that? Are we live in good?”

“People work in Caltech found if they using quantum entanglement technique, they could transform one matter to gas in sudden, and affect matters near it, transform them to the same phase as it, they called it “Phase Assimilation” .”

“That’s powerful, isn’t it?”

“That’s why the Soviet Union let it become a weapon, and create a world we now live in”

The master points outside, the child’s line of insight follows that, ends at the giant ring.

“Do you know the Rings of Saturn?”

“Yes, the rings of Saturn are the most extensive ring system of any planet in the Solar System, that orbit about Saturn. The ring particles are made almost entirely of water ice, with a trace component of rocky material. And that may be formed by objects which come inside the Roche limit and split to pieces…”

“They all taught you in the class, right? But have you ever pay attention to this giant plate around our planet earth?”

The little child stays for silence for a few seconds, looking at the ring. Whispering by his heart: “how couldn’t I notice that elegant thing?”

 It is a huge ring, spreads 300 kilometers wide on the ground on average, around the whole planet. At the start of its formation, the heavier matter of earth first be phase-changed, projectile to the most outside the Roche limit zone of the earth which are the edge of matters comes together or split to pieces, people call it “Heavy Hand”. At that time, the self-rotation axis changed by the unbalanced losing of self-mass, divide the world to two half by the ring, 20% of USSR left the to the side which located with the USA, people later called it the “United hemisphere”, and the rest of the USSR body locate at the another, called the “Communized hemisphere”. The mass of earth still losing due to the gravity force from the “Heavy Hand” and the Centrifugal net force created by the self-rotating, the gravity of the earth is not that strong anymore.

“Yes, Sir, No man-made things could ever come close to the ring…yet, so we disconnect with another hemisphere for 80 years”

“That’s why!” The “master” suddenly goes rage, his eyes extended to large with a crazy laugh, “We live in such buildings, white, immutable. And train you to workers, works for me! To recover the freaking space industry!” He keeps himself in silence for a second, then “I know you would not understand me. I born at the period of the Civil War, really great time. I chose to be a rocket scientist, and rocket chose me. I am 87 years old now, at that time, I am only 17, 17! I am old now, getting old in such a pathetic world. And you, you are all pathetic.

“Sorry, sir… I do not understand, what you mean “pathetic”?”

“You would not understand…forever” The master goes back to cold immediately, no one knows what he exactly thinking about.”

“Should they be called children?” The master stand by, think in his head “These standers are puppets, they could only be free in their “mother’s” wombs” “At the day I become master from rocket scientist, I visited the “Red House” for producing standers, all the things happened still embarked in my head.” “Children originally tend to play and do things they like, people using conditioning to control their future behaviors, if babies tried to play, they would play a very loud shocking noise, I was shocked by that, to be honest. Then these babies would not cry, because…I do not know what they experienced, but they just do cry, after that, they just stop play and stand up for the next instruction. They become the standers. What a “beautiful” world”

“I let you go outside for 35 minutes,” The master said with unexpected

“OK”

“Why? Why? Why? Why does he let me go out? Am I just said anything wrong, would I be killed? What would happen?” beta thinks in his head.

34 minutes, 37 seconds

Beta open the heavy white door, it is the first time he gets out of the house after he got five years ago. He was 2 at that time, now he is seven. The door open with the sound of old, apparently the master himself does not like to walk out.

The world is shockingly the same, Beta still remember there are some men dress in grey walking slowing when he was 2 on the street, but now, things seem to be just an older version of them, just more feeling of fade. People do not talk to each other. There is no brightness in their eyes. They are still walking dead.

“Why the master wants to go out? There are no interesting things, nothing new, just like five years ago”

17 minutes, 14 seconds

The ring still big, strong, even getting larger than before, would people from two sides meet? Do they want to meet?

“It is a beautiful, elegant”

5 minutes, 32 seconds before ship across the “giant hand”

All the people suddenly stand up, do not move, freeze, like old trees but with an unbelievable strong spirit, they are waiting for something, they look at the sky, the ring.

“What’s wrong? What are they doing?”

3…

2…

1…

Beta feel there is something shined a little. Then something he would never forget in his life happens.

People cry, with a smile on their face, old men, young people, grey, white, black…

They are all celebrating. They run to the grassland stand down, smile and cry in silence…

            The world becomes different… become like 80 years ago

            Beta go back to the “home”, he finds the master is smiling, saying: “Our ship met the ship from another side, and we fight…”

            “Our friend is back, the long depression period ends, it is the new beautiful world”

Beta look up, look at the wall, there is a maxim on there:

THE WORLD KEEPS RUNNING, NOT BECAUSE OF PEACE AND LOVE, BUT ENDLESS DISPUTE AND COUNTERMINE

Loading Likes...
{ 0 comments }
Rookie speech 🙂

When a little young baby just born, learning occur at every moment the person lives on the earth, study let people become completed, also helps them to live in this society. One’s future is to decide by learning.
Teachers teach students? Right? But how many of these relationships could be in a highly efficient way? When you in school, how many times you see there are some students set away from the speaker, and do their things but not actually hear what does the person who is currently talking saying? When the people talking accompany with other people’s voice, he could be very tired because he needs to higher the frequency and the intensity of the voice.

So, it is vital to get all the students’ attention at one moment with low cause, but how? Even many strict teachers set roles to his students, after few times class, there always be some students not pay their attention to the teacher at the time they need.


I want to mention my AP Biology teacher, Ms. Rosales, she is the one who demonstrates the psychology tool is such a strong tool to apply in real life.
I still remember the first thing Ms. Rosales ask us to do is something called if…then. It really simple, if she hit the table or things in a certain rhyme, the students should response that with another rhyme for quite.


It looks very simple, and the reality also, but it really let the order of class improve in a massive way. I still remember when Ms. Rosales out of the school for some personal issue, there is a teacher called Ms. Romasa, well, she is kind of nice, but she do not have the what we now called “pa-pa” skill as Ms. Rosales has, mostly, when the class getting disorder and loud, she tries to take the control by yelling in a loud way, that really takes some time and spirit, and only when students think she is angry then they become quite a little. The class still goes on, but not that orderly.


There actually are some very deep and integrated mechanisms behind that. In psychology, what Ms. Rosales apply is called Classical conditioning. There is a very famous experiment did by Palov involved with his dog.


A dog naturally has the willingness to eat meat, so they saliva when they see meat, it is called unconditioned response because it is naturally happening. However, how could we let dog saliva without using meat, but something else, something like…the sound of the ring? The sound of the ring called natural stimuli because the sound of the ring itself has nothing to do with letting dong saliva. What Palov did is ring the ring when he shows the dog with meat, and repeated it for several times, then he finds when he only rings the bell, the dog continues to saliva without meat, the natural stimuli become conditioned stimuli.


What Ms. Rosales do to the students is a similar thing from the perspective of mechanism. At the first days Ms. Rosales began to teach us, she could be very serious because she keeps let students train that. Students naturally response as quiet and tractable when their teacher gets serious. So here teacher get serious is an unconditioned stimulus, and students become quite is an unconditioned response. And the “pa-pa” hits are just natural stimuli, it is true that students know what they should do when they hear it, but their body is not be conditioned yet which means there are not that many people would respond in a quick way. However, after one week’s training, the quantity change cause a quality change, students could response the “pa-pa” sign immediately without any delay, and they would be quiet and pay attention to the teacher.


However, it is not the end, there is something called generalization, which just means the subject would response similar stimuli with one conditioned response or response the stimuli with a similar response. In Palov’s dog experiment, the dog not only responds to the sound of the ring, but other things make a similar sound, like whistle or computer “bi-bi” sound.
Just like in the class, sometimes Ms. Rosales would make different rhyme by mistake, but student response that with same high speed. Also, students would not only be quiet and pay attention to the teacher but also turn down the laptop, iPad or other devices.


The key component here is repeated, if not, extinction happens, or we can say “forget”. If Palov does not train his dog in a certain curve, finally the dog would no saliva to the sound of the ring.
Ms. Romsas had taught us for a long time period, on the first day Ms. Rosales’s class, many students “forget” to respond to the “pa-pa” hit. They got extinction.


To hold the best curve of conditioning? Try to do it in random time gap and random frequency in densely to prevent the appearing of extinction.
Hope you can apply to your life successfully.

Loading Likes...
{ 0 comments }

Boys, set your calculator to polar mode, and draw a graph of
r=4sin(3θ), then set the first interval of [0,π] and the second one: [0, 2π]


[0,π]

[0,2π]

They looks exactly the same, isn’t it?

And if we take of the integral of these two to find the area, for the graph with interval [0,π], area = 4π, but for the graph with [0,2π] the area is 8π, thus, which one is the “true” one we want to find?

I. The Form of Trig Polar Equation

For a trig polar equation, the form is looks like: r=asin(bθ) or cos etc…

a decide the “size of the graph”

b decide the number of “blades”

II. Odd number b and Even number b

The thing is vital :

*The number of blades = 2b

-For even number of b, the blades created are separated(here b=4, so there are 8 “blades”):

-For odd number b, the “blades” are covered with each other, take example of r=4sin(3θ) with [0, 2π], it actually graphed 6 blades, but each two are in the same position covered the another one, so we could only see three. If we do the integral to calculate its area, we get the area of 6 blades.

Thus, if we want to find the area of 3 blades, you can set the interval of [0, π], or just simply divide the area with interval [0, 2π] by two

It’s a very interesting trick dealing with polar equation.

P.S. : hpbsd for me~

Loading Likes...
{ 1 comment }

Landing has been a big problem to Falcon. To achieve the goal of recycling space rocket, SpaceX engineers calculate orbit by many factors, many times the problem is at the moment of landing, people could see the rocket is already on the landing pad on the ocean, but the rocket just not stable and fall down then blow up.

So, if that is possible to set a pad with electromagnet to stick the rocket while landing?

Idea of EM Pad

Loading Likes...
{ 0 comments }

Deemo Chen, grade 11 student. Barstow School – Ningbo Campus.

Abstract

1I/2017 U1 (‘Oumuamua), a recently discovered asteroid in a hyperbolic orbit, is likely the first macroscopic object of extrasolar origin identified in the solar system. This paper mainly gives reasons why ‘Oumuamua should be a comet, by explaining three unusual behaviors of ‘Oumuamua which are unnormal ratio, strange track eccentricity, and Peculiar Acceleration; disproving four main hypothesizes to say ʻOumuamua is not a comet, then provide an evidence of reflectivity of surface of ʻOumuamua to prove ʻOumuamua in a regular interval of comet group. Thus, ʻOumuamua is most likely to be a comet.

Keywords: ʻOumuamua (1I/2017 U1); extraterrestrial intelligenceISM: individual objects (1I&2017 U1)minor planets, asteroids: generalminor planets, asteroids: individual (1I&2017 U1).

Introduction:

ʻOumuamua (1I/2017 U1) is an object from outside of the solar system by first observed by Panoramic Survey Telescope and Rapid Response System(Pan-STARRS) located at Haleakala Observatory, Hawaii, USA (“IAU MPC”), from the IAU website, we can find that ʻOumuamua is also the first object human ever observed from outside the solar system. We are trying to figure out where exactly it came from. The thing is, there are several things shows it is not an ordinary object and can possibility to be a spacecraft may be made by aliens. However, I do not agree with this statement; I tend to describe it is an unusual comet by against three main theories exist which say ʻOumuamua is not a comet.

The ratio and shape of ʻOumuamua

Since we cannot use an optical telescope to truly see how ʻOumuamua looks like, the only way we can use it make the scientific hypothesis of the shape of it.   For a rigid body, it will rotate around the maximum inertia axis(MIA), which is the axis with the most considerable moment of inertia. Dynamically, it can be proved that the rotation of the rigid body around other inertia spindles is unstable if we consider the slight deformation damping of the object.

Figure 1Explorer_1 From NASA Accessed 2019/1/13 https://heasarc.gsfc.nasa.gov/Images/explorer/explorer1.gif

Just like the graph of Explorer_1, which is the first artificial satellite launched by America, it has a long and thin shape. The blue line points the long spindle of Explorer_1, and that is the minimum inertia spindle of this structure, the red line shows the maximum inertia spindle. People at that time hope the satellite could rotate around the long axis, but the result of that be the Explorer_1 cannot stabilize its posture at all, even they did successfully launch the satellite, but Explorer_1 cannot do many planned tasks.

In this way, we can assume that ʻOumuamua is rotating around its MIS. And the diagram below helps us to figure what could be the possible shape of ʻOumuamua.

Light curve of ʻOumuamua. All of the magnitudes have been scaled using the measured colors; the error bars indicate 1σ photometric errors. (Meet, et al. 2)

According to the Light curve of ʻOumuamua, the red dotted line corresponds 10:1:1 triaxial ellipsoid with a 20% variation in albedo across the surface (Meech et al. 2), and the dotted curve made by observation data from different telescopes of ʻOumuamua shows a nearly perfect fitness to the light curve model of a 10:1:1 triaxial ellipsoid. By analyzing the interval between two relative curve minima points, we could approximate the rotating period as 7.34 h. Also, by the hydrostatic balance theory, the size of ʻOumuamua cannot construct itself to be a sphere.

For a rigid body, it is tough to rotate in this way, it will quickly be rapture, and it from outer space and we even cannot figure out it from which galaxy (Ye, et al. 3), so it must have traveled in space for a long time, and that means ʻOumuamua should keep rotating like this for a long time, the possibility of that should be very small, because if P(x)= . P(d) should be minimal (d refers to the distance ʻOumuamua travel, x= ʻOumuamua keep this long and thin shape), and because this shape is too unusual for human, so many people believe ʻOumuamua is an artificial object or spacecraft.

However, the evidence of this hypothesis has some vulnerabilities.

First, the model of the shape of ʻOumuamua have some problem, since we do not have the graphic evidence of the shape, if only according to the light curve, there are much more shapes could fit this model, or there is a light absorbing material covered on, and the following statement about “rigid body” cannot works because other shapes could prevent them from rapture.

Second, we do need to assume that ʻOumuamua is a rigid body, because for a rigid body, they will rupture because of their inside force, so if ʻOumuamua is not a rigid body but made by relatively elasticity materials, in this way, ʻOumuamua could keep a long and thin shape but not broke.

Third, I think even ʻOumuamua truly looks long and thin, that is not a strange thing to human, because if one thing could exist in this world by way we know about physics, then it is properly, “Practice is the sole criterion for testing knowledge”, we should believe in data, whatever how impossible it looks like.

In this way, I think the shape of ʻOumuamua has nothing to doubt about.

The Orbit of ʻOumuamua

Figure 2 Meech, et al. 3

The path of Oumuamua (1I/2017 U1) through the Solar System.

“The orbit of a typical Halley-type comet is shown for comparisonas the solid grey line. The inset shows the inner Solar System; the solid linesegment along the trajectory taken by ‘Oumuamua (dashed)indicates the short window of two weeks during which it was bright” (Meech, et al. 1), As we can see that its track eccentricity is only 1.1956 ± 0.0006, it looks got into the solar system vertically to the zodiac and soon go back the same way, it just like aim to the sun. So, it could easily be seems as a spacecraft want to use the gravity of the sun to redirect its orbit because it is the best way we can think to save the energy for a shuttle.

Orbit offset

Marco Micheli’s team analyzed the full observational dataset, which includes 177 ground-based and 30 HST based astrometric positions (for a total of 414 scalar measurements), applying the procedures and assumptions discussed in Methods. Their analysis shows that the observed orbital arc cannot be fitted in its entirety by a trajectory governed solely by gravitational forces due to the Sun, the eight planets, the Moon, Pluto, the 16 most massive bodies in the asteroid main belt and relativistic effects14. As shown in diagram D1-a, the residuals in right ascension and declination of the best-fitting gravity-only trajectory are incompatible with the formal uncertainties: ten data points deviate by more than 5σ in at least one coordinate, and 25 are discrepant by more than 3σ. Furthermore, the offsets (as large as 22″ for the 2017 October 14 Catalina observation) are not distributed randomly but show clear trends along the trajectory. (Micheli 1)

Diagram 1(D2):

The most reasonable reason for the offset of the orbit is the force of comet dust which will give a power to the object when it spread out of the object, however, by the data from Micheli’s team (Micheli 3), they built a model of comet could have this kind of behavior, they found even 2kg of the dust from the object is enough for telescope  to observe, the thing is, from the actual diagram, we cannot see any dust from ʻOumuamua.

Figure 3Micheli 3

Is that means ʻOumuamua is not a comet but could change its orbit by itself and become a spacecraft? It could be a reasonable guess, but I think there is a better explanation that the object has released only a small quantity of dust, probably in the form of larger grains which are hard to see. 

Also, by the theory of Fitzsimmons’s team, we have another way to explain that there is a cover on ʻOumuamua’s surface which prevents the ice inside of ʻOumuamua spread out from itself, and the cover is so thick that even the sun cannot put effects on ʻOumuamua in that short time, that they reported the spectroscopic characterization of ‘Oumuamua,  and finding it to be variable with time but similar to organically rich surfaces found in the outer Solar System. The observable ISO population is expected to be dominated by comet-like bodies in agreement with our spectra, yet the reported inactivity implies a lack of surface ice. (Fitzsimmons, Alan, et al 4). This is consistent with predictions of an insulating mantle produced by long-term cosmic ray exposure. An internal icy composition cannot, therefore, be ruled out by the lack of activity, even though ‘Oumuamua passed within 0.25 AU of the Sun.

So ʻOumuamua is more likely to be a comet in this way.

The theory to be a LightSailBecause of the usual orbit of ‘Oumuamua, it could consider an artificial origin; one possibility is that Oumuamua is a LightSail, floating in interstellar space as debris

from advanced technological equipment (Bialy 1), As a solar sail, its propulsion is dependent on solar radiation alone. Solar photons exert radiation pressure on the sail, producing a small degree of acceleration. Thus, the solar sail will be propelled by force from sunlight itself, and not by the charged particles of the solar wind.

       Even Mr. Bialy mentioned that ‘Oumuamua could be alien craft since its orbit is so unusual: “Alternatively, a more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.” (Bialy 4)

       It is just an educated guess of the orbit of ‘Oumuamua, but I think this hypothesis did not consider more, because we already prove that ‘Oumuamua is rotating, but if LightSail works, it must let one side of itself toward the sun, so the theory of a LightSail could not work.

The reflectivity of the surface

       Since all hypothesis of saying is not a comet be proved as wrong, here I can give relevant evidence that ‘Oumuamua is a comet.

Figure 4Meech 3

The reflectivity of the surface of ‘Oumuamua. The surface reflectivity of ‘Oumuamua is consistent with D-type asteroids and comets. Data are normalized to 1 at 0.65 μ m, and the error bars reflect the 1σ standard deviation. (Meech 3)

       From the data given by Meech’s team,‘Oumuamua’s reflectivity is pretty close to D-type asteroids and comets, compare to Comet 67P, Comet 9P, and Comet 103P, it does not have much differentness.

One possible way to check what‘Oumuamua truly is

The challenge of reaching the object within a reasonable timeframe is formidable due to its high heliocentric hyperbolic excess velocity of about 26 km/s (Hein 1); Much faster than any vehicle yet launched, Launching a spacecraft to ’Oumuamua in a reasonable timeframe of 5-10 years requires a hyperbolic solar system excess velocity between 33 to 76 km/s for mission durations between 30 to 5 years. (Hein 4) It is demonstrated that based on existing technologies now human have such as from the Parker Solar Probe, launchers such as the Falcon Heavy and Space Launch System could send spacecraft with masses ranging from dozens to hundreds of kilograms to 1I/’Oumuamua, if launched in 2021. A further increase in spacecraft mass can be achieved with an additional Saturn flyby post solar Oberth maneuver. The potential of more advanced technologies such as laser electric propulsion, solar and laser sails would also allow for chasing ’Oumuamua, although their development will likely push launch dates farther into the future and might be more attractive for reaching future ‘Oumuamua-like objects. And we can chase it in 2029.

Conclusion

Even the shape of ’Oumuamua is strange. Its orbit changes but we cannot observe any dust, and the model is suitable to be a LightSail, but all we can find a reasonable explanation. So `Oumuamua is a comet –a tiny one, with perhaps different chemistry and an unusual shape, but colored like Solar System comets, and outgassing like our comets or covered with an organic layer. So, we were indeed lucky to find it, but we did not need to be too fortunate to find an interstellar asteroid.  And we still have the chance to take a clear picture of this comet to see how exactly it looks like if we want to.

Works Cited

Bialy, Shmuel, and Abraham Loeb. “Could Solar Radiation Pressure Explain ‘ʻOumuamua’s Peculiar Acceleration?” The Astrophysical Journal Letters 868.1 (2018): L1.

<http://iopscience.iop.org/article/10.3847/2041-8213/aaeda8/meta>. Accessed on 19 December 2018.

Fitzsimmons, Alan, et al. “Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 ‘ʻOumuamua.” Nature Astronomy 2.2 (2018): 133.

<https://www.nature.com/articles/s41550-017-0361-4>. Accessed on 19 December 2018.

Hein, Andreas M., et al. “Project Lyra: Sending a Spacecraft to 1I/’ʻOumuamua (former A/2017 U1), the Interstellar Asteroid.” arXiv preprint arXiv:1711.03155 (2017).

<https://arxiv.org/abs/1711.03155>. Accessed on 19 December 2018.

Meech, Karen J., et al. “A brief visit from a red and extremely elongated interstellar asteroid.” Nature 552.7685 (2017): 378.

<https://www.nature.com/articles/nature25020>. Accessed on 19 December 2018.

Micheli, Marco, et al. “Non-gravitational acceleration in the trajectory of 1I/2017 U1 (‘ʻOumuamua).” Nature 559.7713 (2018): 223.

< https://www.nature.com/articles/s41586-018-0254-4>. Accessed on 19 December 2018.

“The International Astronomical Union Minor Planet Center.” IAU Minor Planet Center, minorplanetcenter.net//iau/lists/MPDiscsNum.html.

https://minorplanetcenter.net//iau/lists/MPDiscsNum.html. Accessed on 8 January 2018

Ye, Quan-Zhi, et al. “1I/2017 U1 (‘ʻOumuamua) is hot: imaging, spectroscopy, and search of meteor activity.” The Astrophysical Journal Letters 851.1 (2017): L5.

<http://iopscience.iop.org/article/10.3847/2041-8213/aa9a34/meta>. Accessed on 19 December 2018.

Loading Likes...
{ 0 comments }