The Insane Engineering of the DART Mission

Summary

2022年9月26日，NASA执行了一项历史性任务，发射了一个570公斤的航天器以每秒6公里的速度撞击名为Dimorphos的小行星，以测试其轨道改变能力。这次撞击实验相当于3吨TNT的爆炸力，成功改变了小行星的轨道，减少了其绕Didimos运行的轨道周期32分钟。通过地球上的望远镜和哈勃、韦伯望远镜的观测，科学家们能够精确测量这次撞击的效果。这次任务不仅展示了人类有能力改变小行星轨道以避免潜在的地球撞击，还测试了新的离子推进器技术和太阳能电池板。这次成功的实验为地球防御提供了宝贵的数据和工具。

Takeaways

• 🚀 2022年9月26日，NASA发射了一个570千克的航天器，以每秒6公里的速度撞击了一个名为Dimorphos的小行星，这是人类历史上首次进行的行星防御测试。
• 🦖 这次任务被称为DART（双小行星重定向测试），旨在测试通过撞击改变小行星轨道的可能性，以防止类似恐龙灭绝的灾难再次发生。
• 🛰️ DART航天器设计简单，没有携带科学仪器，主要装备有用于导航的相机、星跟踪器、推进系统和天线系统，以及基于军事导弹技术的软件。
• 📹 意大利制造的小型航天器被释放出来，记录了撞击过程，捕捉到了从小行星表面喷射出的大量碎片。
• 🎯 选择Dimorphos作为目标小行星是因为它是一个双星系统的一部分，这使得科学家能够通过地球望远镜观测撞击效果。
• 🌌 Dimorphos在撞击时距离地球1100万公里，这个距离允许科学家精确预测小行星的位置，并选择最佳的撞击窗口。
• 🔭 通过地球望远镜观测Dimorphos在Didimos前经过时的光变，科学家能够测量撞击前后Dimorphos轨道的变化。
• 🚀 DART航天器使用了自主导航系统，配备了类似PlayStation 1的电路和12个方向推力器，以及新一代的离子推进器。
• 🌟 DART还测试了一种新型的太阳能电池板，这些电池板能够从卷轴中展开，并集中太阳光以增加太阳能电池板的效率。
• 🎉 NASA在撞击后两周宣布，DART任务成功地将Dimorphos的轨道改变了4.5%，减少了其绕Didimos的轨道周期32分钟，证明了人类有能力改变小行星的轨道。
• 📚 这次任务不仅提供了关于小行星地质成分和撞击动力学的重要数据，还展示了如何利用引力物理学和航天器技术来保护地球免受小行星威胁。

Q & A

2022年9月26日，一个570公斤的宇宙飞船以每秒多少公里的速度撞击了一颗小行星？

2022年9月26日，一个570公斤的宇宙飞船以每秒6公里的速度撞击了一颗小行星。

这次任务使用的是什么型号的火箭？

这次任务使用的是燃料驱动的Falcon 9火箭。

这次撞击小行星的任务被称为什么？

这次撞击小行星的任务被称为DART（双小行星重定向测试）。

被撞击的小行星Dimorphos直径是多少？

被撞击的小行星Dimorphos直径是160米。

如果Dimorphos小行星与地球相撞，它释放的能量相当于多少兆吨TNT？

如果Dimorphos小行星与地球相撞，它释放的能量相当于超过300兆吨TNT。

DART任务的宇宙飞船携带了哪些设备？

DART任务的宇宙飞船携带了相机、星跟踪器、推进系统、天线系统以及一个基于军事导弹技术的飞行计算机。

DART任务释放的小型意大利制造的宇宙飞船有什么作用？

DART任务释放的小型意大利制造的宇宙飞船用于记录撞击过程，提供了撞击时从小行星上喷射出的巨大碎片的影像。

为什么选择Dimorphos作为撞击目标？

选择Dimorphos作为撞击目标的原因是它接近地球，且有一个小月亮绕着较大的小行星Didimos运行，这使得从地球上可以测量撞击效果。

如何从地球上测量Dimorphos小行星的轨道变化？

通过使用地面望远镜观察Dimorphos在Didimos前面经过时的光变，可以测量其轨道周期，并据此测量撞击后轨道的变化。

DART任务使用的自主导航系统是如何工作的？

DART任务使用的自主导航系统通过搭载的相机和小型望远镜每秒拍摄一张照片，并计算所需的推力，以保持正确的轨迹，类似于军事应用中的Javelin导弹的视觉制导软件。

DART任务使用的离子推进器NEXT-C有什么特点？

DART任务使用的离子推进器NEXT-C比NASA之前一代的离子推进器强大三倍，通过电磁场加速氙离子至每秒40公里的极高速度。

DART任务的太阳能电池板有什么特别之处？

DART任务的太阳能电池板是特别开发的轻量级太阳能电池板，它们从卷轴中展开，称为卷出式太阳能阵列（ROSA），并在2017年在国际空间站上成功测试。

DART任务撞击后对Dimorphos小行星轨道的影响有多大？

DART任务撞击后，Dimorphos小行星的轨道改变了4.5%，其绕Didimos的轨道周期从11小时55分钟减少到11小时23分钟。

Outlines

00:00

🌌 小行星撞击实验

2022年9月26日，一颗重达570公斤的航天器以每秒6公里的速度撞击了一颗小行星。这次任务是NASA有史以来最重要的实验，旨在收集可能拯救地球免受小行星撞击的数据。目标小行星Dimorphos直径160米，比导致恐龙灭绝的小行星小得多，但足以在撞击地球时释放出超过300兆吨的能量。科学家们花了多年时间规划这次任务，包括选择目标、确定撞击方式以及如何快速准确地测量撞击效果。

05:02

🌕 双小行星系统

为了测量撞击效果，科学家选择了一个双小行星系统，其中Dimorphos绕着更大的小行星Didymos运行。这个系统的选择是因为我们可以从地球上测量轨道变化。使用地基望远镜观测，科学家们测量了Dimorphos的轨道周期为11小时55分钟。这些数据将帮助我们确定撞击对小行星轨道的影响。

10:02

🎯 精准撞击与后续影响

在两周的数据收集后，NASA宣布撞击成功，Dimorphos的轨道周期缩短了32分钟。这次任务不仅展示了我们能够偏转小行星的能力，还为未来保护地球提供了宝贵的数据和工具。任务的成功极大地增强了我们在太空中保护地球的信心。

Keywords

💡DART任务

DART（双小行星重定向测试）任务是美国宇航局（NASA）进行的一项实验，目的是通过撞击改变小行星的轨道。这项任务展示了如何在未来可能威胁地球的小行星到来之前采取措施来避免碰撞。这项任务的成功不仅显示了人类防御行星的能力，还提供了大量数据用于未来的行星防御计划。

💡Dimorphos

Dimorphos是DART任务的目标小行星，是一个直径约160米的小行星。科学家选择它作为目标是因为它离地球较近且其轨迹已被精确预测。通过撞击Dimorphos，科学家能够测量撞击对其轨道的影响，这对于未来的行星防御任务非常重要。

💡Falcon 9

Falcon 9是SpaceX公司开发的可重复使用的火箭，用于将DART航天器送入太空。该火箭使用化石燃料推进系统，是DART任务成功的关键部分之一，确保航天器能够到达并精确撞击目标小行星Dimorphos。

💡小行星重定向

小行星重定向指通过人为干预改变小行星的轨道以避免其与地球碰撞。DART任务是首次实际执行的此类任务，旨在测试是否可以通过撞击小行星来改变其轨道，从而保护地球免受潜在的小行星撞击威胁。

💡Didymos

Didymos是一颗较大的小行星，Dimorphos是其卫星。选择这个系统进行DART任务是因为科学家可以通过观察Dimorphos绕Didymos的轨道变化来准确测量撞击的效果。

💡自主导航系统

自主导航系统是DART航天器的一部分，负责在无人工干预的情况下精确引导航天器撞击小行星。由于信号延迟，手动控制不切实际，因此航天器使用相机和推进系统自主调整轨道，以确保成功撞击目标。

💡离子推进器

离子推进器是一种高效的推进系统，使用电磁场加速氙离子。DART任务使用了下一代离子推进器（NEXT-C），尽管在任务过程中遇到了一些问题，但展示了其在深空任务中的潜力和重要性。

💡光学导航

光学导航是通过摄像机捕捉图像并分析这些图像来确定航天器位置和方向的技术。DART航天器使用这种技术来实时调整其飞行路径，以确保准确撞击Dimorphos。

💡动能冲击

动能冲击是指通过高速碰撞将动能传递给目标物体，以改变其运动轨迹。在DART任务中，动能冲击用于改变小行星Dimorphos的轨道，以测试这种方法在行星防御中的有效性。

💡行星防御

行星防御是保护地球免受小行星或其他天体撞击的科学和技术。DART任务是行星防御领域的一次重要实验，通过实际撞击测试了改变小行星轨道的方法，为未来的行星防御任务提供了宝贵的数据和经验。

Highlights

2022年9月26日，一个570公斤的航天器以每秒6公里的速度撞击了一颗小行星，这是NASA执行的最重要的实验之一，其数据和信息可能有一天能拯救我们免于恐龙的命运。

被撞击的小行星Dimorphos直径为160米，如果撞击地球，释放的能量将超过300兆吨，是历史上使用过的最强大核武器的六倍多。

自撞击以来，科学家一直在研究结果，计算我们的第一次小行星偏转测试的有效性。

DART航天器没有携带科学仪器，设计为低成本航天器，只配备了完成任务所需的工具。

DART释放了一个意大利制造的小航天器，记录了撞击过程，显示从小行星喷射出的巨大碎片羽流。

Falcon 9火箭完成了大部分工作，将DART指向目标Dimorphos。

Dimorphos是一个独特的目标，因为它是一个没有卫星的小行星，这使得研究撞击结果成为可能。

DART的相机在飞越Dimorphos时，让我们一窥这颗小行星，并在最后920公里的冲刺中调整其轨迹。

选择Dimorphos的原因是它接近地球，我们能够准确预测它在任何给定时间的位置，这使我们能够选择最佳的碰撞窗口。

撞击Dimorphos的目标是仅用足够的力量改变其轨迹，足以避免与地球的碰撞，即使是1%的改变也可能足以避免灾难。

科学家通过研究双星系统来测量撞击后小行星轨迹的微小变化，Dimorphos绕着较大的小行星Didimos运行，并且从地球上可以看到它在Didimos前面经过和背后。

通过测量Dimorphos在Didimos前面经过时的光变，科学家能够测量其轨道周期，并使用相同的技术测量撞击后轨道的变化。

DART航天器配备了自主导航系统，能够在1.5分钟的延迟下，自动调整轨迹以击中目标。

DART使用了下一代离子推进器NEXT-C，比NASA之前的离子推进器强大三倍。

NEXT-C离子推进器使用新型轻量级太阳能电池板供电，这些电池板在2017年已经在国际空间站上成功测试。

NASA在10月10日宣布，撞击使Dimorphos的轨道周期减少了32分钟，从11小时55分钟减少到11小时23分钟，偏转效果比预期的1%要好得多。

这次任务是一个巨大的成功，我们现在有信心，如果需要，我们可以偏转像Dimorphos这样的小行星。

这次任务主要是为了收集关于这种撞击如何影响小行星轨道的数据，并回答有关小行星的地质组成以及它如何影响从DART到Dimorphos的动量转移的问题。

通过这次任务，我们现在拥有了保护我们星球的数据和工具，我们在这片漂浮在广阔、神秘空间中的小岩石上更安全了一点。

Transcripts

on the 26th of September 2022 a 570

kilogram spacecraft the size of a

refrigerator rammed into an asteroid at

six kilometers per second launched

aboard the fossil fueled powered Falcon

9 the dinosaurs finally clapped back

66 million years after the asteroid that

ended the dinosaurs an unsuspecting

asteroid was struck with an impact

equivalent of three tons of TNT and we

caught it all on film this mission is

perhaps the most important experiment

NASA has ever performed data and

information that could one day save us

from the same fate as the dinosaurs

the asteroid we struck dimorphos is 160

meters in diameter much smaller than the

10 kilometer wide asteroids that

exterminated the dinosaurs all those

years ago but large enough to unleash

over 300 megatons of energy if it

collided with Earth six times more

powerful than the most powerful nuclear

weapon ever used

in the week since scientists have been

studying the results calculating how

effective our first asteroid redirection

test was however the work that went into

this mission Far extends the last month

of scientific study for years scientists

and Engineers carefully planned which

asteroid to hit how to hit it and how to

confidently and quickly measure the

effect of the Collision

to understand the achievement of the

dart Mission let's dive into the

engineering and physics of its Planet

defense mission

the dart spacecraft itself hosted no

scientific instruments designed to be a

low-cost spacecraft with just the tools

it needed to complete its Mission

cameras to spot its Target star trackers

to navigate through space a propulsion

system to direct it toward its Target

antenna systems to speak with Earth and

an onboard computer whose software has

its roots in military missile

Technologies

however darsh did release a small

italian-made spacecraft designed to

record the Collision giving us this

footage showing a massive plume of

debris being ejected from the asteroid

on impact

the Falcon 9 rocket did the majority of

the work in directing dirt toward its

Target dimorphos this was a unique

Target chosen for a very important

reason

it's a moonless a tiny Moon orbiting the

larger asteroid didimos

dart's camera gave us a glimpse of

didimos as it sailed by at a Breakneck

speed closing down the remaining 920

kilometers in just two and a half

minutes it computed and adjusted its

trajectory using hydrazine thrusters

guiding the spacecraft to a head-on

impact with the moonlit in these final

moments dirt shut down its thrusters

allowing the camera to take clear images

of its impending doom and giving us a

clear picture of the rock we just

obliterated 11 million kilometers away

so why this rock in particular

there are countless asteroids orbiting

the Sun however in order to study the

results of impact we need a specific

kind of asteroid

first dimorphos was passing close to

Earth passing by at 11 million

kilometers at the time of impact

we have tracked dimorphos and have

confident predictions of where the

asteroid is going to be at any given

point in time this allowed us to choose

an optimal window for Collision our

model showed that on October 4th 2022

the asteroid would be at its closest

approach for the next 40 years the next

time it would be this close to Earth be

2062 this was the perfect opportunity

however we struck it a week early

because the asteroid would be at its

brightest to us at its closest approach

allowing us to better observe the

results of the Collision

this is the next reason this asteroid

was chosen the goal of the double

asteroid redirection test was to

redirect an asteroid with just enough

Force to change its trajectory by a

marginal amount enough to avoid a

collision with Earth a change of just

one percent could be enough to avoid a

catastrophe But Here Lies The Dilemma

for scientists how do we measure such a

small change in trajectory of an object

11 million kilometers away even the

footage from a spacecraft near the

Collision is not much to go off

confidently measuring an impact with an

asteroid orbiting the Sun would take

years as we'd need to measure multiple

orbits to assess the differences before

and after the impact instead scientists

turned to Binary systems for answers

there are systems of asteroids where one

smaller moonless orbits a larger

asteroid all we need to know is that we

changed the velocity of a moving rock in

space it doesn't matter if it's orbiting

the Sun or orbiting another rock however

not any binary system would make this

experiment feasible it is essential that

we can measure the effectiveness of the

crash from Earth for this the orbiting

moonlit should have an eclipsing path

meaning that viewed from Earth it would

pass in front of and behind the asteroid

during its orbit the light reflecting

from these two asteroids that we see

here on Earth appears as a single point

of light and each time dimorphos passes

in front of didimos that light dims

using sensitive earth-based telescopes

we have timed these patterns to measure

the orbit of dimorphos at 11 hours 55

minutes using these same techniques we

can measure the change in orbit

dimorphos is only visible from the

southern hemisphere so NASA reserved

time on telescopes located in Chile

South Africa Australia and New Zealand

joining the earth-based telescopes Webb

and Hubble were also used to image the

asteroids at the time of impact of

course to achieve all this we first

needed to hit the asteroid that was no

easy feat the asteroid was too far away

to manually direct the spacecraft there

would be a lag of 1.5 minutes

six kilometers per second a lag this

large would help the spacecraft travel

over 540 kilometers before receiving

instructions when trying to hit a Target

only 160 meters in diameter lags like

this required an autonomous navigation

system

the spacecraft was loaded with the

camera attached to a small 20 centimeter

wide telescope and circuitry no more

powerful than that of a PlayStation 1.

every second it would take a picture and

calculate the thrust needed to stay on

chorus working very similarly to visual

Guidance Software used in military

applications like the javelin missile

Dart used 12 directional thrusters to

hit the small dim moonless

dirt was also equipped with the next

generation of ion thrusters next C which

is three times more powerful than NASA's

previous generation ion Thruster inster

ion thrusters are highly efficient

accelerating heavy ions of xenon to

extreme speeds of 40 kilometers per

second using an electromagnetic field 10

times faster than a traditional rocket

engine

these ion thrusters were powered by new

specially developed lightweight solar

cells that deploy from a roll called a

roll out solar array or Rosa this solar

array was successfully tested on the ISS

in 2017 although in a strangely

hilarious video the arrays were gently

ejected from the ISS because there was a

fault in retracting them at the end of

the test part of the solar array was

also used to demonstrate a new solar

collector technology that would

concentrate sunlight on high efficiency

panels increasing their power deep in

our solar system where solar radiation

rapidly drops off thanks to the inverse

Square law

a technology that would be extremely

useful for powering an ion Thruster

allowing us to reach asteroids further

from Earth and giving us a better chance

of changing their trajectory early these

systems were successfully tested on dirt

however Ed Reynolds the DART program

manager at APL revealed in a post-impact

briefing that the next SEA Thruster was

actually only tested for a short

two-hour period during flight an

unexpected issue arose that could have

cost 100 amps of current to run through

the Thruster which it had not been

tested to withstand forcing the team to

make a decision to not continue testing

the Thruster instead relying completely

on the hydrazine thrusters to focus on

the primary asteroid redirect Mission

and while this is disappointing finding

a new issue is an important part of the

testing process and it didn't impact the

mission at all

the mission itself was a massive success

after just two weeks of gathering data

NASA announced on October 10th the

effects of the Collision

striking only 17 meters from the

asteroid Center there's practically

struck the bullseye not just changing

its orbit by one percent but by a

relatively massive 4.5 percent reducing

its orbit around didimos by 32 whole

minutes down from 11 hours 55 minutes to

11 hours 23 minutes

this is a mission worth celebrating we

are now confident we can deflect an

asteroid like dimorphos if the need

arises Beyond Moon missions Beyond Mars

missions beyond all the understanding

NASA and other space agencies provide us

this Mission has clear understandable

importance we now have data and tools in

our Arsenal to protect our planets we

are now a little safer on this little

rock floating through the vast

mysterious expanses of space

this mission was primarily designed to

gather data on how a collision like this

would affect the orbit of an asteroid

there were many questions to be answered

about the geological composition of the

asteroid and how that would affect the

transfer of momentum from dirt to

dimorphos especially as most asteroids

of this size are simply piles of rubble

that have coalesced due to gravity over

time and aren't a single solid Mass

making exact predictions on the

Collision physics and how the orbit

would be affected very difficult

basic calculations of gravitational

physics are pretty easy to learn however

and understanding them gives you all

sorts of fun Powers unlocking the

knowledge of space travel and planetary

motion you can learn more about that by

taking this course on brilliant and when

you are done you can move over to our

very own real engineering course all

this is available to you by signing up

to Brilliance free trial with the link

in the description and if you found

value in the math and science courses

you took for free and I'm sure you will

you can continue with 20 off the annual

premium subscription this offer is only

available to the first 500 people to

sign up our in-depth interactive course

teaches you about the physics of orbit

and traditional rocket launches before

teaching you about the fundamentals of

kinetic launch systems a course designed

to help you understand spin launch the

subject of a recent documentary you can

get access to that course right now and

all of brilliant's other curated

interactive courses by clicking the link

in the description a fantastic course to

start is computer science fundamentals

the perfect course for high school or

college students starting their Journey

on computer science this course will

teach you core computer science Concepts

and when you are done you can move on to

more advanced courses like programming

with python brilliant teachers with

interesting and fun interactive courses

that challenge you along the way making

the learning process much easier and

more rewarding and they're adding

content monthly so there's always

something new to learn you can get

started for free by clicking the link on

screen right now the first 500 people to

do so will get 20 off Brilliance annual

premium subscription