J*******3
发帖数: 1651 | 1 本人用SIESTA. 一个general的问题。
通常情况下，设计一个体系，假设选用了Atomic orbitals 作basis，用cutoff radius
和orbital撒数来控制计算精度。这时，那些控制planwaves 和realspace grid 的参
数们都不起作用了吗？换句话说，他们对计算没什么贡献了，对吗？ |
|
J*******3
发帖数: 1651 | 2 为什么？ basis 的选择 通常有三个options：1） atomic orbital 2）plane wave
3） real space without basis。 他们不是平行的吗？ 我的意思是一旦用其中一个
，例如说 1， 那就是说我们用 atomic orbital 同展开 KS equation,另外两个以及相
关的参数在计算过程中就被neglected? 不对吗？ |
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s****s
发帖数: 66 | 3 我觉得你说的没错，我简单算了一下Natural Bond Orbital，还是基于
hyperconjugation的角度去解释：
NBO分析里的second order perturbation给出其他成键轨道对C=O anti-bonding
orbital的donation能量。简单的说就是先把分子轨道处理成localized的，然后考虑各
个轨道在一起相互之间有没有mix导致能量相对上升下降，和原子间轨道成键导致成键
轨道和反键轨道的原理是类似的。我算了对于四元环和五元环的两个进行比较，NBO给
出对C=O anti-bonding轨道有较大能量贡献的是临近两个C上的C-H键。其实这就是典型
的hyperconjugation效应。四元环分子的second order energy比较小，五元环分子的
second order energy比较大，所以四元环的C=O比五元环的C=O键强，四元环的C=O振动
频率大。
当然是否有其他原因还可以进一步分析。如果你要做也可以继续扩展到六元环体系。
前面说的用local mode的分析觉得不是很好，对这样的小分子必须要考虑到整个分子的
... 阅读全帖 |
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e****2
发帖数: 2723 | 4 bromoethene
BR shows higher electronegtivity than I , thus stable the corresponding
carbonanion.
d orbital dorbital interaction HG S
better than d s orbital interaction between hg o
H2C
hydrogen |
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h**********c
发帖数: 4120 | 5 for example, we want to show how a periodic orbit approaches a saddle node ;
that is where a homoclinic orbit is brought to existence. |
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p********t
发帖数: 1219 | 6
FEATURE
NASA Names Orion Contractor
08.31.06
Orion crew in lunar orbit Lessons from the past are guiding NASA's next step
into the future, as the space agency prepares to replace the space shuttle
with an Apollo-style vehicle for human explorers.
Image left: Orion in lunar orbit. Image credit: Lockheed Martin Corp.
The vehicle is Orion, named for one of the brightest and most recognizable
star formations in the sky. It will be a multi-purpose capsule -- the
central member of a family |
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v****x
发帖数: 980 | 7 Thanks. 上面说Geostationary satellite就被放到disposal orbit that has a perigee at
least 300 km above the geostationary orbit.
那么其它卫星呢?sun-synchronous的,比如 Landsat1-5? |
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n*********r
发帖数: 18 | 8 All rights reserved!
(Draft version)
(2) Carrier transport. (In amorphous organic semiconductors)
OLED materials are conjugated (the bonds between the carbon atoms are
alternately single and double). The p electrons are completely delocalized
along the conjugated carbons. Hence, their charge transport properties can be
affected by the p - p* molecular orbital overlap. However, the overlap of
molecular orbitals and intermolecular electron exchange are much smaller than
their inorganic counterpar |
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m***y
发帖数: 14763 | 9 I once read an article about how to build a space elevator using nano ropes
(actually, it's more like a band or a sheet). First, a big roll of rope is
sent to the static orbit and one end of rope dropped from there. When the
rope reaches the ground, small robots can climp up the rope, sending up more
ropes. Eventually, we will have enough ropes to support a space elevator!
Yup, people laugh at this joke. But amazingly, nobody doubts the nano rope
is strong enough to drag the load to the orbit! S |
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s*********s
发帖数: 18 | 10 为什么理论预测graphene spin diffusion length 可达到100 um,但实际测量还不到
10um, 室温只有1-2 um 在single layer graphene. 另外：Spin life time is 50-
200ps, the order of magnitude shorter than expected from the intrinsic spin-
orbit coupling(-us).The results indicates that the presence of the extrinsic
spin relaxation mechanism.
请前辈指点。
why graphene for spintronics?
1. Extraordinary high mobility
>200000cm2v-1s-1 (suspended , low temperature)
>40000cm2v-1s-1 (on sio2 , room temperature)
-------Future high-speed transistor... 阅读全帖 |
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m*******s
发帖数: 3142 | 11 diffusive是canonical molecular orbital的图像，
但是通常的化学家都用localized molecular orbital图像,这个不是本征函数
上面的回答似乎在说，如果creator, annihilator的选取正好和本征函数对应，那么不
管是什么Hamiltonian描述的体系，Green's function也应该是那个简单结果。
似乎有如下推论：只有写成对角化形式的Hamiltonian，才可以直接看出Green's
function的结果。 不知道是不是这样的。 |
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C**R
发帖数: 1047 | 12 IM(1/epsilon)是对光子吸收的几率。对光子吸收的cross section，就像你说的，使用
来算。排除exchange-correlation的近似外，dft计算的是ground state，而
且计算的不是真正的wave function。这个dft算出来的single electron k-s orbitals
，严格讲只对charge density 有意义，本身没有实际的物理意义。但是经验上发现，k
-s orbitals的能级和实验上可以吻合，所以可以暂时认为有意义。
好，再回到光子吸收的问题上，这个时候实际上是个exitation的问题。如果你还记得
hartree-fock的话，你就知道，当你把某个electron放个位置的话（比如2p放到3d)，
实际上你的core electron是要重新relax的（如果core hole/exciton life time足够
长的话）。这就是说,你的光子吸收，probe的不是ground state valence band to
conduction band的hopping问题，而是有excit |
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l**n
发帖数: 908 | 13 说句实话，连spin-orbit coupling究竟是咋样作用的还没有在真正的物理和数学层面
解释呢，而现在已经有很多理论建立在这个强coupling的基础上了。
不管是理论文章还是实验文章，最后都是一句，材料有很强的spin-orbit coupling。
nobody could say anything beyond that。
spin hall effect号称不一定要铁磁。但真实情况是，所有claim看到SHE或者inverseSHE
的实验中，必定用到了铁磁材料做电极——你可以一篇一篇地查，无一例外。在device
制作过程中又涉及很多nanofabrication的process，这些铁磁材料很可能污染所谓的‘
nonmagnetic’材料。去年阿贡实验室的一篇prl文章就指出在完全没有涉及磁性材料的
情况下gold是没有很明显的she效应的，正好跟08年nature material上一篇日本人的文
章完全相反——而那里用到了磁性材料做电极。
真的要在物理界做，很多话在公开的场合还是不敢直说的。这些就当八卦好了。
至于TI嘛，我只是觉得这一行太需要它了。 |
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c******x
发帖数: 67 | 14 【 以下文字转载自 Postdoc 讨论区 】
发信人: communix (东东), 信区: Postdoc
标 题: University of Florida招聘两个第一性原理博士后
发信站: BBS 未名空间站 (Mon Jul 19 14:12:21 2010, 美东)
该课题组今年年初招了两个博士后，现在准备再招两人。需要有第一性原理、量子化学
或相关领域的编程经验。
We seek two additional Postdocs. The Dept. of Energy has funded our project
on orbital-free free-energy density functional theory for warm dense matter
and we are underway.
详情见
http://www.qtp.ufl.edu/~trickey/
一点背景：
QTP做理论的牛人聚集
项目负责人之一Trickey是Wien2k程序的早期作者之一
一点建议：
orbital-free DFT和warm dense matter都是新兴热门领域 |
|
J*******3
发帖数: 1651 | 15 本人用SIESTA. 一个general的问题。
通常情况下，设计一个体系，假设选用了Atomic orbitals 作basis，用cutoff radius
和orbital撒数来控制计算精度。这时，那些控制planwaves 和realspace grid 的参
数们都不起作用了吗？换句话说，他们对计算没什么贡献了，对吗？ |
|
J*******3
发帖数: 1651 | 16 是这样理解的吗？ basis 的选择 通常有三个options：1） atomic orbital 2）
planewave 3） real space without basis。 他们不是平行的吗？ 我的意思是一旦
用其中一个，例如说 1， 那就是说我们用 atomic orbital 同展开 KS equation,另外
两个以及相关的参数在计算过程中就被neglected? 对吗？ |
|
s***e
发帖数: 5242 | 17 by Freeman Dyson
12/2010
In 1946 Subrahmanyan Chandrasekhar gave a talk at the University of Chicago
entitled “The Scientist.” 1 He was then 35 years old, less than halfway
through his life and less than a third of the way through his career as a
scientist, but already he wa reflecting deeply on the meaning and purpose of
his work. His talk was one of a series of public lectures organized by
Robert Hutchins, then the chancellor of the university. The list of speakers
is impressive, and included ... 阅读全帖 |
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s*********s
发帖数: 18 | 18 为什么理论预测graphene spin diffusion length 可达到100 um,但实际测量还不到
10um, 室温只有1-2 um 在single layer graphene. 另外：Spin life time is 50-
200ps, the order of magnitude shorter than expected from the intrinsic spin-
orbit coupling(-us).The results indicates that the presence of the extrinsic
spin relaxation mechanism.
请前辈指点。
why graphene for spintronics?
1. Extraordinary high mobility
>200000cm2v-1s-1 (suspended , low temperature)
>40000cm2v-1s-1 (on sio2 , room temperature)
-------Future high-speed transistor... 阅读全帖 |
|
c******7
发帖数: 439 | 19 补充一下, 我是想定性的分析一下,
想用经典模型类比一下, 说明角量子数L越大, spin-orbit coupling越强.
我觉得spin-orbit coupling越强要求电子越深入内壳层.
这样被屏蔽的少.而且电子速度快.
这样要求电子的"轨道"比较扁, 然后对于量子系统, L越大轨道越扁.
但我推出来对于经典情形,L越大轨道越圆,所以我有点惊讶.
我想我有一个主要的困惑在于,
如何才能有一个有磁场下的,符合量子力学的运动.
用洛伦兹力的话就受限于v的引入.
如果用矢势A的话,又不太直观.
我之所以想用经典的轨道,就是因为能用洛伦兹力. |
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t*******e
发帖数: 216 | 20 spin-orbit coupling与你之前的问题本身应该没有直接的关系。
spin首先是没有经典对应的，楼主自然应该知道spin的力学算符是没有经典力学量对应
的。所以我认为本身你希望用经典模型来类比这个耦合本身就不是一个值得做的事情。
如果你只是希望在量子力学内研究这个耦合，最直接的就是去看氢原子的光谱，氢原子
目前是可以精确计算的，http://en.wikipedia.org/wiki/Lamb_shift
耦合问题可以归结于氢原子能级在添加了spin-orbit的H量之后带来的修正。这样比较
不同L带来的修正即可得到理论计算的结果。当然实验上对于氢原子测量，楼主需要查
阅MPQ Garching的最新结果。 |
|
z**********g
发帖数: 16 | 21 继续发表有关斥力子的文章，请指正。
“斥力子理论”对物理学的影响1
庄一龙
近年来，由中国学者创立的“斥力子理论”，经过中国科学院《科技促进发展》《
科技成果管理与研究》、《科技中国》、《中国科技财富》、《中国科技成果》等主流
科技杂志报导后，引起了学术界广泛重视。那么，这一理论究竟有那些观点震动了学术
界，值得人们如此关注呢？
“斥力子理论” 是一种新物质作用理论，实际上也是一种物理哲学理论。它的代
表性文章是《论“斥力子”的存在及其意义》，另外还包括《相对性效应和牛顿定律的
本质》、《物理学中精细结构常数的理论推导与解释》等几十篇论文。同牛顿的苹果从
树上掉下来的万有引力理论相对应，这是一个可称作“苹果如何转移到树上去的‘万有
斥力’理论”。该理论认为，地面的物体一旦动起来，不管方向如何，都具有一种挣脱
地球引力的能力，就好象物体吸收了一种对抗万有引力的物质那样。“斥力子理论”把
普朗克能量子看作是一种对抗引力的实物粒子，称它为“斥力子”，并认为物体运动状
态的改变就是由于吸收或释放斥力子造成的。
在思维方法上，它有两个根本突破：其一,是把抽象的能量概念实物化，使能量有
一个实物载... 阅读全帖 |
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z**********g
发帖数: 16 | 22 Discussing The Existence of “repulsion particle” And Its Significance
Zhuang Yiliong
Shanghai Institute of Science and Technology Management
Abstract:This report has advanced a assume about the existence of “
repellention” by a kind of new idea. Beginning with this, I have explained
more successfully some import theory questions in the area of the present
physics, cosmology and philosophy ect. At same time a few of new reasons
have been raised But this is only rough idea of physica... 阅读全帖 |
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发帖数: 1 | 23 Best of Last Year—The top Phys.org articles of 2017
December 19, 2017 by Bob Yirka, Phys.org report
Study reveals substantial evidence of holographic universe
A sketch of the timeline of the holographic Universe. Time runs from left to
right. The far left denotes the holographic phase and the image is blurry
because space and time are not yet well defined. At the end of this phase (
denoted by the …more
It was another great year for science, particularly physics, as evidenced by
a study conducte... 阅读全帖 |
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t****n
发帖数: 1347 | 24 我本以为本版高人众多,所以点到为止,没有细说,
没想到说了半天还没人提到 Moon recession, Tidal friction之类
的东西,只好抄一段给大家看:
From Encyclopedia Britannica:
tidal friction
in astronomy, strain produced in a celestial body (such as
the Earth or Moon) that undergoes cyclic variations in
gravitational attraction as it orbits, or is orbited by, a
second body. Friction occurs between water tides and sea
bottoms, particularly where the sea is relatively shallow,
or between parts of the solid crust of planet or satellite
that move against each |
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o*****m
发帖数: 3 | 25 谢谢，刚才google了一下，发现你说的都是对的
Sun-Earth distance: 149,598,000 km
Moon-Earth distance:384,000 km
radius of Sun: 440,000 miles
radius of Moon:1,080 miles
Eccentricity of Orbit Earth: 0.017
Eccentricity of Orbit Moon: 0.05 |
|
F***t
发帖数: 412 | 26 When it is about the same distance from the Sun
as is Jupiter, a spacecraft on a mission to the outer
planets has a speed that is 1.5 times the speed of
Jupiter in its orbit. Which of the following describes
the orbit of the spacecraft about the Sun?
(A) Spiral
(B) Circle
(C) Ellipse
(D) Parabola
(E) Hyperbola
答案为E。
但我觉得似乎得假设Jupiter的轨道为圆形，或近乎圆形。
因为如果Jupiter的轨道为椭圆形，则在各点的速度不同。
如果飞船速度是Jupiter在其近地点速度的1.5倍，那么
飞船将沿双曲线飞离太阳。
如果是远地点速度的1.5倍，则不一定能飞离太阳。
请指正。 |
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M*********m
发帖数: 2024 | 27 Do you guys really believe that the following object could lift off from the
moon and dock back to the commanding module orbiting the moon in the late
1960s? From the Soviet Union technology at that time, it was highly possible
to send man orbiting around the earth.
I am not saying that there was no such possibilities, but it is such a
tremendous task even by current technology standard? Welcome your comments. |
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c**d
发帖数: 3888 | 28 You mean an orbital buffer? I never tried it...
Hand + towel has served me well. Orbital buffers make me nervous... |
|
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w*******y
发帖数: 60932 | 30 Just saw the current Gold Box:
http://www.amazon.com/gp/goldbox
offer at Amazon is Griot's Garage 6" Machine Polish and Wax Kit:
http://www.amazon.com/dp/B003V3XBCM
, regularly $200, for $120 after $80 Gold Box coupon. The random orbital
buffer is well-reviewed and goes for $130 by itself (no pads), so you're
getting a polishing pad, a waxing pad, polish, wax, cleaner, clay bar, and
instructions for free. I'm in for 1, here's hoping I have the discipline to
use it.
Gold box: Gold Box:
http:/... 阅读全帖 |
|
|
y*j
发帖数: 394 | 32 Edward Lu
http://www.jsc.nasa.gov/Bios/htmlbios/lu.html
"A veteran of three space missions, Dr. Lu has logged over 206 days in space
, and an EVA (spacewalk) totaling 6 hours and 14 minutes. In August 2007, Dr
. Lu retired from NASA in order to pursue private interests."
"SPACE FLIGHT EXPERIENCE: STS-84 Atlantis (May 15-24, 1997), was NASA’s sixth Shuttle mission to rendezvous and dock with the Russian Space Station Mir. In completing this mission, Dr. Lu traveled 3.6 million miles in 144 orbits... 阅读全帖 |
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s******o
发帖数: 298 | 33 从www.space.com的一篇文章上cut一段：）
Ancient visitor returns
Soon after a preliminary orbit was calculated for Ikeya-Zhang, some orbital
experts, lead by Syuichi Nakano of Japan, noticed a similarity to a pair of
much earlier comets that appeared in 1532 and 1661.
The 1532 comet, in particular, was a strikingly bright comet, according to
Oriental records. Curiously, during the first week or two that Ikeya-Zhang
was under careful scrutiny by observers worldwide it appeared to be brightening
at an unusuall |
|
s******o
发帖数: 298 | 34 March 15, 2002 | Mars Odyssey, the latest orbiter to start mapping the red
planet, is back to full working order. Its cameras have always worked fine,
but last August controllers lost communication with Odyssey's Mars Radiation
Environment Experiment (MARIE) while the craft was still en route to Mars.
The broken component — designed to measure the radiation danger that future
travelers to Mars might encounter — was largely ignored until the craft
reached its low mapping orbit in February and eng |
|
s******o
发帖数: 298 | 35 By Robert Roy Britt
Senior Science Writer
posted: 02:00 pm ET
17 April 2002
Eccentricity has been redefined in our solar system with the measurements of
a pair of objects that orbit each other out in the dark and cold stomping
grounds of Pluto.
Last April, researchers announced that an object named 1998 WW31, a comet-like
body orbiting the Sun in the solar system's fringes, had a companion. A new
study, which will be published in the April 18 issue of the journal Nature,
finds that the pair's co |
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s******o
发帖数: 298 | 36 A halo globular cluster gets shredded by our galaxy.
by Phil Plait
Orbiting the Milky Way can be hazardous to your health. Although most objects
serenely orbit our home galaxy, astronomers are now detecting invisible deadly
forces wreaking havoc upon some of them. Gravity, which keeps star, clusters,
and nebulae bound to the Milky Way, can also tear them apart.
The newest victim found is Palomar 5, a roughly 13-billion-year-old globular
cluster 75,000 light-years away. New observations of the cl |
|
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s*****t
发帖数: 1994 | 38 The Seasons of Saturn
Credit: R. G. French (Wellesley College) et al., Hubble Heritage Team (AURA / STScI /
NASA)
Explanation: Since Saturn's axis is tilted as it orbits the Sun, Saturn has seasons, like those
of planet Earth ... but Saturn's seasons last for over seven years. So what season is it on Saturn
now? Orbiting the equator, the tilt of the rings of Saturn provides quite a graphic seasonal
display. In fact, this month, Saturn's ring |
|
s*****t
发帖数: 1994 | 39 Five to Mars
Image Credit: USGS, Viking Project, NASA
Explanation: Come December 2003 - January 2004, an armada of five new invaders from
Earth should arrive on the shores of the Red Planet -- the Japanese ( ISAS) Nozomi orbiter,
the European Space Agency's Mars Express orbiter carrying the Beagle 2 lander, and NASA's
own two Mars Exploration Rovers. While Nozomi began its interplanetary voyage in 1998,
the other spacecraft are scheduled for launch windows beginning this June. Cl |
|
s*****t
发帖数: 1994 | 40 A Mercury Transit Sequence
Credit & Copyright: Dominique Dierick
Explanation: Earlier this month, the planet Mercury crossed the face of the Sun, as seen
from Earth. Because the plane of Mercury's orbit is not exactly coincident with the plane of
Earth's orbit, Mercury usually appears to pass over or under the Sun. The above time-lapse
sequence, taken from a balcony in Belgium on May 7, shows the entire transit. The solar
crossing lasted over five hours, so that the above 23 im |
|
s*****t
发帖数: 1994 | 41 Martian Moon Phobos from MGS
Credit: Malin Space Science Systems, MGS, JPL, NASA
Explanation: Why is Phobos so dark? Phobos, the largest and innermost of two Martian
moons, is the darkest moon in the entire Solar System. Its unusual orbit and color indicate
that it may be a captured asteroid composed of a mixture of ice and dark rock. The above
picture was captured recently by the robot spacecraft Mars Global Surveyor (MGS) orbiting
Mars. Phobos is a heavily cratered and barren moon, |
|
s*****t
发帖数: 1994 | 42 HD70642: A Star with Similar Planets
Illustration Credit & Copyright: David A. Hardy, PPARC
Explanation: Astronomers have discovered a planetary system more similar to our own
Solar System than any known previously. The bright star HD70642, visible with binoculars
toward the constellation of Puppis, was already known to be a star like our Sun. Now a planet
with twice Jupiter's mass has been discovered in a nearly circular orbit at approximately half
the orbital distance of Jupiter. Su |
|
s*****t
发帖数: 1994 | 43 Mars Rising Through Arch Rock
Credit & Copyright: Wally Pacholka (Astropics)
Explanation: Mars is heading for its closest encounter with Earth in over 50,000 years.
Although Mars and Earth continue in their normal orbits around the Sun, about every two
years Earth and Mars are on the same part of their orbit as seen from the Sun. When this
happens again in late August, Mars will be almost as near to the Sun as it ever gets, while
simultaneously Earth will be almost as far from the |
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s*****t
发帖数: 1994 | 44 Light Can Twist as Well as Spin
Credit & Copyright: M. J. Padgett, J. Leach (U. Glasgow) et al., Royal Society
Explanation: Light is more complicated than we thought. When astronomers measure light, they are usually
concerned with its direction, energy, and spin polarization (sometimes). Recently, however, it has been more
broadly realized that photons can also have orbital angular momentum (OAM), an attribute classically analogous
to the Earth orbiting the Sun as well as spinning on |
|
s*****t
发帖数: 1994 | 45 The International Space Station from Above
Credit: STS-114 Crew, NASA
Explanation: The International Space Station (ISS) is the largest human-made
object ever to orbit the Earth. Last August, the station was visited and
resupplied by space shuttle Discovery. The ISS is currently operated by the
Expedition 13 crew, consisting a Russian and an American astronaut. After
departing the ISS, the crew of Discovery captured this spectacular vista of
the orbiting space city high above the Caspian Sea. Vi |
|
s*****t
发帖数: 1994 | 46 Janus: Potato Shaped Moon of Saturn
Credit: CICLOPS, JPL, ESA, NASA
Explanation: Janus is one of the stranger moons of Saturn. First, Janus
travels in an unusual orbit around Saturn where it periodically trades
places with its sister moon Epimetheus, which typically orbits about 50
kilometers away. Janus, although slightly larger than Epimetheus, is potato-
shaped and has a largest diameter of about 190 kilometers. Next, Janus is
covered with large craters but strangely appears to lack small cra |
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s*****t
发帖数: 1994 | 47 Spirit Rover on Mars Imaged from Orbit
Credit: HiRISE, MRO, LPL (U. Arizona), NASA
Explanation: If you have the right equipment, you can see the Spirit rover
currently rolling across Mars. The right equipment, however, is currently
limited to the High Resolution Imaging Science Experiment onboard the Mars
Reconnaissance Orbiter (MRO). MRO arrived at Mars in March and just started
science observations of the red planet last month. Visible in the above
spectacularly high resolution image is the Sp |
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c**i
发帖数: 6973 | 48 (1) Niall Ferguson, In China's Orbit; After 500 years of Western
predominance, Niall Ferguson argues, the world is tilting back to the East.
Wall Street JOurnal, Nov. 18, 2010.
http://online.wsj.com/article/SB10001424052748704104104575622531909154228.html
My comment:
(a) The essay states,"Per capita gross domestic product, they show,
stagnated in the Ming era (1402-1626) and was significantly lower than that
of pre-industrial Britain."
List of regions by past GDP (PPP) per capita
http://en.wikip... 阅读全帖 |
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w*********g
发帖数: 30882 | 49
Waiting for the aircraft carriers/orbit bombers/nuclear submarines... to
service in the army. |
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M*V
发帖数: 3205 | 50 space x 是怎么回事 [ 红绿 ] 于:2012-06-01 23:34:42 主题帖
首先，spacex是不是一家私人公司？ 这个毫无疑问，是。但也没这么简单。公司存在
差不多十年了，Musk投入了大约1亿美元的个人资产。其他的投资基金，私人资产加起
来也有差不多1亿。十年的总运营费用大概是10亿。这钱大部分来自美国宇航局（NASA)
的项目基金5亿美元。这五亿可不是普通意义上的服务费用。其中的最重要的2到3亿是
NASA给spacex的种子基金，这个种子基金通过COTS（Commercial Orbital
Transportation Services）项目给的。这个项目很有意思，它不是普通的合同，
spacex拿到钱，如果做不出东西，它也无需承担任何合同的责任（不过，nasa需要看到
一些私人资金的投入意愿）。天下还有如此好事？是的。spacex还不是第一个尝鲜的人
。spacex的前辈公司就拿了几千万美元的这个钱，但因为据说nasa看不到诚意，截断了
剩下的接近2亿美元投入，转而找其他人去了。spacex迅速加入战团，拿到订单。这钱
太重要了，spacex早期弄的Fal... 阅读全帖 |
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