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Chinese Space Station Crash: Why It's So Hard to Predict Where Space Debris Will Land
Space.com ^ | March 29, 2018 07:19am ET | Matteo Ceriotti, University of Glasgow |

Posted on 03/29/2018 12:57:17 PM PDT by BenLurkin

Newton’s laws tell us that satellites orbit the Earth in perfectly circular or elliptical orbits, repeating their path again and again (assuming that gravity is the only force acting on them). However, this is not true at low altitudes, say below 1,000km, because the satellite is then moving through the Earth’s atmosphere. This causes “aerodynamic drag” (air resistance) – a force that opposes the satellite’s velocity, which effectively turns the orbit into a downward spiral towards the Earth’s surface.

In theory, we can calculate drag perfectly to predict the path of a satellite. This can be done using an equation that depends on the velocity of the satellite (v²), the density of the atmosphere (ρ), a numerical coefficient that depends on the shape of the satellite and its orientation with respect to the airflow (C), and the object’s area (A). For those who are interested, the equation is: D = ½ × C × ρ × A × v². But you don’t have to understand the equation to grasp why it is so hard to calculate drag.

The spacecraft’s velocity is easy to measure fairly accurately using observations. However, the other parameters are highly uncertain – making it difficult to determine Tiangong-1’s path. For vehicles such as cars and aircraft, C can be estimated theoretically or with computational fluid dynamics and measured experimentally in a wind tunnel. The main problem here is that Tiangong-1’s shape is complex, and the object is uncontrolled and tumbling chaotically, resulting in a constantly changing C.

The other unknown is the density of the atmosphere, which decreases with altitude. However, particularly at high altitudes, this varies due to a number of unpredictable factors – the most important of which is solar activity.

(Excerpt) Read more at space.com ...

TOPICS: Science
KEYWORDS: china; elonmusk; falcon9; falconheavy; spacex
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1 posted on 03/29/2018 12:57:17 PM PDT by BenLurkin

To: BenLurkin

I predict it will land on my house!............................................[I’m always wrong!]......................

2 posted on 03/29/2018 12:58:07 PM PDT by Red Badger (The people who call Trump a tyrant are the same people who want the president to confiscate weapons.)

I was hoping on Hoggs house with him in it.

3 posted on 03/29/2018 1:00:10 PM PDT by dforest (Never let a Muslim cut your hair.)

To: BenLurkin

Hamtramk MI, molenbeek belgium, Malmo Sweden.

4 posted on 03/29/2018 1:00:18 PM PDT by I want the USA back (Lying Media: willing and eager allies of the hate-America left.)

5 posted on 03/29/2018 1:00:48 PM PDT by BenLurkin (The above is not a statement of fact. It is either satire or opinion. Or both.)

To: BenLurkin

The odds-makers in Vegas should be working on this one....

6 posted on 03/29/2018 1:01:13 PM PDT by EagleUSA

To: I want the USA back

“Hamtramk MI, molenbeek belgium, Malmo Sweden.”

Mecca ?

.

7 posted on 03/29/2018 1:03:30 PM PDT by Mears

8 posted on 03/29/2018 1:05:37 PM PDT by bobby.223 (Retired up in the snowy Mountains of the American Redoubt and it's a great life!)

To: BenLurkin

Call me crazy but I suspect it might hit the earth.

9 posted on 03/29/2018 1:06:48 PM PDT by MeganC (There is nothing feminine about feminism.)

To: BenLurkin

Its at least as hard as trying to predict when Hillary will stop blaming everyone else for her election loss.

10 posted on 03/29/2018 1:08:07 PM PDT by Secret Agent Man ( Gone Galt; Not averse to Going Bronson.)

To: Secret Agent Man

I predict she will blame the space station for her loss.

11 posted on 03/29/2018 1:09:19 PM PDT by Puppage (You may disagree with what I have to say, but I shall defend to your death my right to say)

To: bobby.223

I don’t think Alaska is in the danger zone...................

12 posted on 03/29/2018 1:09:39 PM PDT by Red Badger (The people who call Trump a tyrant are the same people who want the president to confiscate weapons.)

To: EagleUSA
"If the Martians land, they're gonna need a place to stay. Just like everybody else."

13 posted on 03/29/2018 1:10:09 PM PDT by BenLurkin (The above is not a statement of fact. It is either satire or opinion. Or both.)

To: BenLurkin

14 posted on 03/29/2018 1:11:46 PM PDT by leaning conservative (snow coming, school cancelled, yayyyyyyyyy!!!!!!!!!!!)

To: BenLurkin

Laboratories crashing out of the sky, diplomats being ejected in Russia — did I freaking wake up in the 70s?

15 posted on 03/29/2018 1:11:58 PM PDT by freedumb2003 (robert mueller is an unguided missile)

To: MeganC

I give it about 3 chances in 4 of hitting water.

16 posted on 03/29/2018 1:12:07 PM PDT by rdl6989

To: BenLurkin

So you are saying that earth’s atmosphere is rotating at up to 1000mph, even though this cannot be demonstrated in a laboratory.

And still, just as the same way we have no actual real photos of the earth from space (only fake composites), we have no actual photos of the over 250,000 pieces of broken satelites and space debris in the sky.

Only photoshopped composites.

It’s all so weird.

But then again, we are relying not on our own eyes and our own senses and our own common sense in these matters, but State-run agencies for evidence and proof.

It’s like trusting the DMV about science.

17 posted on 03/29/2018 1:13:29 PM PDT by Sontagged (Lord Jesus, please frogmarch Your enemies behind You as You've promised in Your Word)

To: BenLurkin

I need a new roof!..........................

18 posted on 03/29/2018 1:16:19 PM PDT by Red Badger (The people who call Trump a tyrant are the same people who want the president to confiscate weapons.)

To: Sontagged

Don’t know about you but I’m wearing a hard hat until this thing has fallen

19 posted on 03/29/2018 1:17:24 PM PDT by WilliamIII

To: Sontagged
Here's a pic of Earth from Apollo 10. Nothing weird about it.

20 posted on 03/29/2018 1:19:48 PM PDT by BenLurkin (The above is not a statement of fact. It is either satire or opinion. Or both.)