earth science

Upper Atmosphere Research Satellite

Upper Atmosphere Research Satellite is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Upper Atmosphere Research Satellite rather than just read about it. In short: The Upper Atmosphere Research Satellite (UARS) was a NASA-operated orbital observatory whose mission was to study the Earth's atmosphere, particularly the protective ozone layer. The 5,900-kilogram (13,000 lb) satellite was deployed from Space Shuttle Discovery during the STS-48 mission on 15 September 1991.

Key takeaways

Upper Atmosphere Research Satellite belongs to earth science; place it in that map before memorising details.
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Reference excerpt

The Upper Atmosphere Research Satellite (UARS) was a NASA-operated orbital observatory whose mission was to study the Earth's atmosphere, particularly the protective ozone layer. The 5,900-kilogram (13,000 lb) satellite was deployed from Space Shuttle Discovery during the STS-48 mission on 15 September 1991. It entered Earth orbit at an operational altitude of 600 kilometers (370 mi), with an orbital inclination of 57 degrees. The original mission duration was to be only three years, but was extended several times. When the mission finally ended in June 2005 due to funding cuts, 14 years after the satellite's launch, six of its ten instruments were still operational. A final orbit-lowering burn was performed in early December 2005 to prepare the satellite for deorbit. On 26 October 2010, the International Space Station performed a debris-avoidance maneuver in response to a conjunction with UARS. The decommissioned satellite re-entered Earth's atmosphere on 24 September 2011. Considerable media attention surrounded the event, largely due to NASA's predictions that substantial parts of the satellite might reach the ground, potentially endangering inhabited areas. However, the satellite ultimately impacted in a remote area of the Pacific Ocean.

Instruments

Chemical studies

Cryogenic Limb Array Etalon Spectrometer (CLAES)

CLAES was a spectrometer that determined the concentrations and distributions of nitrogen and chlorine compounds, ozone, water vapor and methane. This platform produced the first global maps of ozone depleting chlorinated compounds. It did this by inferring the amount of gases in the atmosphere by measuring the unique infrared signature of each gas. In order to differentiate the relatively weak signature of trace gases from the background radiation in the atmosphere, CLAES had to have high resolution and sensitivity. To achieve this, the instrument combined a telescope with an infrared spectrometer. The whole instrument was cryogenically cooled to keep heat from the instrument from interfering with the readings. The cryogenics system consisted of an inner tank of solid neon at −257 °C (−430 °F) and an outer tank of solid carbon dioxide at −150 °C (−238 °F). As the neon and carbon dioxide evaporated, they kept the instrument cool for a planned 19 months. The final cryogens evaporated from the instrument on May 5, 1993, and the instrument warmed up, ending its useful life. The instrument looked sideways out of the UARS platform to allow the instrument to look through the stratosphere and the lower mesosphere. CLAES produced a 19-month global database showing the vertical distributions of important ozone-layer gases in the stratosphere and their variation with time of day, season, latitude, and longitude.

Improved Stratospheric and Mesospheric Sounder (ISAMS)

ISAMS is an infrared radiometer for measuring thermal emission from the Earth's limb (the line of the horizon as seen from UARS), on both sides of the spacecraft. It used the pressure-modulation technique to obtain high spectral resolution, and innovative stirling-cycle coolers to achieve high detector sensitivity. ISAMS uses 7 gas cells for 6 different gases: CO2 (times 2), CO, CH4, N2O, NO2 and H2O. The CO2 cells also allow measurement of ozone (O3), nitric acid (HNO3) and dinitrogen pentoxide (N2O5) The specific objectives of ISAMS were: (i) To obtain measurements of atmospheric temperature as a function of pressure, from the tropopause to the mesopause, with good accuracy and spatial resolution, and hence to study the structure and dynamics of the region, (ii) To investigate the distribution and variability of water vapour in the middle atmosphere, to determine its role in the atmospheric general circulation, and its sources and sinks in the middle atmosphere, (iii) To measure the global distribution of oxides of nitrogen and hence to investigate their origins and their roles in catalytic cycles which control the amount of ozone in the stratospheric ozone layer. It also made extensive observations of volcanic aerosols and polar stratospheric clouds in the middle atmosphere. The instrument operated from September 1991–July 1992.

Microwave Limb Sounder (MLS)

The MLS detected naturally occurring microwave thermal emissions from Earth's limb to create vertical profiles of atmospheric gases, temperature, pressure and cloud ice. MLS looks 90° from the angle of UARS' orbit. Thermal radiation enters the instrument through a three-mirror antenna system. The antenna mechanically scans in the vertical plane through the atmospheric limb every 65.5 seconds. The scan covers a height range from the surface up to 90 km (55 miles). Upon entering the instrument, the signal from the antenna is separated into three signals for processing by different radiometers. The 63 GHz radiometer measures temperature and pressure. The 183 GHz radiometer measures water vapor and ozone. The 205 GHz radiometer measures ClO, ozone, sulfur dioxide, nitric acid and water vapor. As late as June 2005, the 63 and 205 GHz radiometers remained operational, but the 183 GHz radiometer failed after 19 months of operation.

Halogen Occultation Experiment (HALOE)

HALOE uses solar occultation to measure simultaneous vertical profiles of ozone (O3), hydrogen chloride (HCl), hydrogen fluoride (HF), methane (CH4), water vapor (H2O), nitric oxide (NO), nitrogen dioxide (NO2), temperature, aerosol extinction, aerosol composition and size distribution versus atmospheric pressure at the Earth's limb. The measurements are done at eight different wavelengths of infrared across a 1.6 km (0.99 mi) wide field of view of Earth's limb. A vertical scan of the atmosphere was obtained by tracking the sun during occultation. The scan will measure the amount of solar energy absorbed by gases in the atmosphere. In order to support scanning, the instrument came in two parts, the optics unit on a two-axis gimbal and a fixed electronics unit. The optics unit contains a telescope that collects solar energy as well as the gas detectors. The electronics unit handles data, motor control and power for the instrument.

Dynamics

High Resolution Doppler Imager (HRDI)

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Illustrations

Worked examples

Example 1 — a first encounter with Upper Atmosphere Research Satellite

Start with the simplest possible case. Write down what Upper Atmosphere Research Satellite claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Upper Atmosphere Research Satellite before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Upper Atmosphere Research Satellite ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Upper Atmosphere Research Satellite

In research: Upper Atmosphere Research Satellite appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Upper Atmosphere Research Satellite in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Upper Atmosphere Research Satellite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Earth observation satellites of the United States, Geospace monitoring satellites, NASA satellites orbiting Earth, so understanding it makes those chapters shorter.
In everyday life: Look for Upper Atmosphere Research Satellite outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Upper Atmosphere Research Satellite in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Upper Atmosphere Research Satellite means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
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Frequently asked questions

What is Upper Atmosphere Research Satellite in simple terms?

Why does Upper Atmosphere Research Satellite matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Upper Atmosphere Research Satellite?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Upper Atmosphere Research Satellite.