How high does the atmosphere go?

We were wanting to look at information that one would need, in order to calculate how long it would take for the NASA UARS satellite to reach the earth's surface once it entered the atmosphere. 

You can read more about satellites here http://www.nasa.gov/audience/forstudents/5-8/features/what-is-a-satellite-58.html

This concept was obviously "theoretically" only and was not be accurate in any way but its was project we decided to look at.

At the end of it we realised that we needed to learn more about the difference between speed, acceleration and velocity.  There were also a couple of other things that we learnt.

At first we thought that if we could get certain info such as mass, speed and distance, we could use one of the physics formulas we had learnt about to work this out.  

We had a look at this website http://www.ucar.edu/learn/1_1_2_2t.htm  How high does the atmosphere go?  It turned out that each of the websites we looked had different measurements but we used the first one as it was only a theory we were looking at.

The info on the website, states that the "thickness" of the atmosphere (the distance between the earth's surface and the "top" of the atmosphere) is not an exact measure. 

On this site they stated that the atmosphere is made up of 2 layers.  The layer that is closest to the earth is the Troposphere (7 miles. The Upper layer of the atmosphere is called the Stratosphere (29 miles).

The approximate measure of the atmosphere is therefore 36 miles. (according to this website).  We used this measurement.  

(There is also info on http://www.enchantedlearning.com/subjects/astronomy/planets/earth/ which states "The Earth's atmosphere is about 300 miles (480 km) thick, but most of the Earth's atmosphere is within 10 miles (16 km) of the Earth's surface.") *but we had used the first info for our theory - no matter.

If we used the formula:  Time = distance / velocity we considered that we could work out, theoretically, how long the satellite would take to reach the surface.  Obviously there are many factors involved, including friction (burn up), gravity, rotation of the earth, path of the satellite etc.

We get the velocity from this website:  

Time = distance / velocity

Time = 36  miles / 18000m/h   

Time = 0.002 hours

To convert this we x by 3600s (1 hour)

Time = 7.2 seconds.

--------------------

(Is this the correct way to convert to seconds ? - I think it is)

This is a very short time but it does make some sort of sence, if you consider that when we think we see a falling star, it is actually only a piece of space debris or meteor etc entering the atmosphere.  The time that a falling star takes is seconds as well!

Here is another site that again has different measurements and additional layers to the atmosphere.  http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html.  They list the layers of the atmosphere as Trophoshere , Stratosphere, Ionosphere and Mesosphere = 550km in total.

We also used these measurements in the same formula:

Time = distance / velocity

Time = 550km / 28968.19km per hour (18000m/h)

Time =  0.019 hours

To convert this we x by 3600s (1 hour)

Time = 68 seconds

--------------------

After this we looked at the NASA website for info on the atmosphere.  Again it has different info and more layers, going upto 600km.  http://www.nasa.gov/audience/forstudents/9-12/features/912_liftoff_atm.html  This has the most info and presumably it is accurate as they have done a lot of research.

***One interesting thing we did find out BTW is that NASA are crashing this satellite intentionally!  That's something to think about.  We also learnt about orbital debris and how much there is in orbit.

EXTRACT  "Its orbit was been altered by Nasa deliberately to make it crash – but it is now coming down sooner than expected due to changed atmospheric conditions."

Read more: http://www.dailymail.co.uk/sciencetech/article-2040818/Satellite-falling-earth-1-3-200-chance-NASA-UARS-hit-person.html#ixzz1YnL4pVvX

-------------------------
Next we looked at the formula

Force = mass x acceleration

We know the mass is 6 tonnes and 1 tonnes = 1000 kilograms therefore the satellite is 6000kg. This info of 6 tonnes comes from news reports and the NASA site.  Acceleration is 18000 miles per hour. (Note:  This figure of 18000 miles/hour comes for http://www.dailymail.co.uk/sciencetech/article-2040818/Satellite-falling-earth-1-3-200-chance-NASA-UARS-hit-person.html and other sites) 

So Force = 6000kg x 18000 miles per hour

Force is measured in Newtons (N) therefore

Force = 108 000 000 N ??

---------------------------------

Alternatively if I convert the 18000 miles per hour to km/h, I get  28968.19km per hour.  (I used this to convert miles to km  http://www.calculateme.com/Speed/MilesperHour/ToKilometersperHour.htm)

My calculation for Force would then be = 6000kg x 28968.19km per hour

Force = 173 809 140 N

-------------------------

In any event both answers are extreme amounts of Force!  

Bear in mind, though that the satellite is set to burn up and break up the final force will differ.  This is theoretical only.  It would also make a difference to the answer in Newtons, if you use km/h or m/h. (As shown).  I think it is correct to use Km/h and not m/h for calculations, however in the UK the unit of measure is m/h so how does this effect Newton calculations.    As I am just learning about these formulas and force/mass/velocity etc - these are all just thoughts and I know I am only learning and can get things wrong.

Its interesting to think about things....

I want to look more at the difference between speed, acceleration and velocity.  They are both measured in m/s and km/h.... - depending on what system your country uses - what unit should you use for calculations??  As it gives different answers!  Also want to look at the difference between weight and mass.

----------------------------------

Read this website to learn how satellites stay in orbit...http://library.thinkquest.org/C007258/Keep_Orbit.htm

It seems they travel a distance and fall closer to the earth during that travelling (like a ball when you throw it).  Because the earth has constant curves the satellite does not actually fall into the earth.  It just has constant movement around the earths curves.  You have to read the article yourself to understand it.

News: Hello - UARS Satellite....

UARS is a Nasa satellite, which has come out of orbit and is heading on a collision course towards Earth.

The lastest update from NASA is:

UARS Updates

Update #9

Fri, 23 Sep 2011 03:01:35 AM GMT



As of 9:30 p.m. EDT Sept. 22, 2011, the orbit of UARS was 110 mi by 115 mi (175 km by 185 km). Re-entry is possible sometime during the afternoon or early evening of Sept. 23, Eastern Daylight Time. The satellite will not be passing over North America during that time period. It is still too early to predict the time and location of re-entry with any more certainty, but predictions will become more refined in the next 24 hours.

Source:  http://www.nasa.gov/mission_pages/uars/index.html

Here is an artists impression of the the satellite (NASA):

UARS was originally launched on Sept. 15, 1991 as an "Upper Atmosphere Research Satellite", designed for a three-year mission .  After 20 years orbiting the earth its on its way out .  UARS  actually came to end of it official life when it was decommissioned on Dec. 14, 2005.   Its main functions were to measure chemical compounds found in the ozone layer, wind and temperature in the stratosphere, as well as the energy input from the sun. Together, these measurements helped define the role of Earth's upper atmosphere in climate and climate variability. 

Its size is 35-foot-long, 15-foot-diameter !

According to those in the know, they predict that it 'could land anywhere' between 57 degrees N and 57 degrees S.  That's most of the inhabited earth.  Although there are areas of desert, ocean and jungle which do not support populations of people, there are many who are quite hysterical with worry over being hit by this satellite or pieces of it.

Though NASA only give a 1:3200 chance that it will hit a human. With a world population of 7 billion people, I wonder if their ratio is correct and if it takes all factors into account.  How accurate do you think their ratio is.

Obviously its their satellite and they will want to downplay its downfall and the damage it can do.

Weighting a mere 6 tonnes and hurtling toward earth, it is predicted to break into 26 pieces.  Each of those pieces is predicted to land over an area of 500km.

Think of the speed they are travelling and the force at which they will collide with, when they do. Also consider that because they are entering the atmosphere this causes much of the 6 tonnes to burn up. The pieces that do collide with the earth will therefore either be on fire/in the process of burning up or unbelievably, boiling hot.

Read all about it here: http://www.nasa.gov/mission_pages/uars/uars_science.html
 http://www.bbc.co.uk/news/science-environment-14955984
http://news.bbc.co.uk/today/hi/today/newsid_9598000/9598111.stm
Video of satellite falling http://www.bbc.co.uk/news/science-environment-15009337

Info on orbital debris from NASA http://www.nasa.gov/news/debris_faq.html

Geology: Rock Cycle

The rock cycle is an illustration that explains how the three rock types are related to each other, and how processes change from one type to another over time.

It describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous.

Each type of rock is altered or destroyed when it is forced out of its conditions.

An igneous rock such as basalt may break down and dissolve when exposed to the atmosphere (water, temperature, pressure, wind) or melt as it is forced by fault lines to go under a continent.

Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in stable balance / equilibrium and are forced to change as they encounter new environments.

A diamond is a mineral from within an igneous or metamorphic rock that formed at high temperature and pressure.

for image see source
---------------------------------------------------
Source:  http://en.wikipedia.org/wiki/Rock_cycle