science

Special Sensor Ultraviolet Limb Imager

Special Sensor Ultraviolet Limb Imager is a 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 Special Sensor Ultraviolet Limb Imager rather than just read about it. In short: The Special Sensor Ultraviolet Limb Imager (SSULI) is an imaging spectrometer that is used to observe the earth's ionosphere and thermosphere. These sensors provide vertical intensity profiles of airglow emissions in the extreme ultraviolet and far ultraviolet spectral range of 800 to 1700 Angstrom (80 to 170 nanometre) and scan from 75 km to 750 km tangent altitude.

Key takeaways

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Reference excerpt

The Special Sensor Ultraviolet Limb Imager (SSULI) is an imaging spectrometer that is used to observe the earth's ionosphere and thermosphere. These sensors provide vertical intensity profiles of airglow emissions in the extreme ultraviolet and far ultraviolet spectral range of 800 to 1700 Angstrom (80 to 170 nanometre) and scan from 75 km to 750 km tangent altitude. The data from these sensors will be used to infer altitude profiles of ion, electron and neutral density. The Naval Research Laboratory (NRL) developed five ultraviolet remote sensing instruments for the Air Force Defense Meteorological Satellite Program (DMSP). These instruments known as SSULI (Special Sensor Ultraviolet Limb Imager) launched aboard the DMSP block of 5D3 satellites, which started in 2003. SSULI measures vertical profiles of the natural airglow radiation from atoms, molecules and ions in the upper atmosphere and ionosphere by viewing the Earth's limb at a tangent altitude of approximately 50 km to 750 km.

Overview The United States Naval Research Laboratory (NRL) built five of these ultraviolet spectrographs for the United States Air Force (USAF) Defense Meteorological Satellite Program (DMSP) block of 5D3 satellites.

Launch The first sensor was launched on the DMSP F16 spacecraft in October 2003 into a Sun-synchronous 830 km circular orbit at a local time of 0800-2000 UT. Three of the remaining four SSULIs were launched on the following DMSP Block 5D3 satellitesDefense Meteorological Satellite Program#Block 5D:

DMSP F17 - November 4, 2006 DMSP F18 - October 18, 2009 DMSP F19 - April 3, 2014 The last SSULI is at NRL awaiting a new "ride" due to the cancellation and preservation of the last DMSP satellite.

Mission details Measurements are made from the extreme ultraviolet (EUV) to the far ultraviolet (FUV) over the wavelength range of 80 nanometers to 170 nanometers, with 1.8 nanometer resolution. The satellites will be launched in a near-polar, Sun-synchronous orbit at an altitude of approximately 830 km. The Low Resolution Airglow and Auroral Spectrograph (LORAAS), a SSULI prototype, was launched on board the Advanced Research and Global Observation Satellite (ARGOS_(satellite)) on February 23, 1999. LORAAS data was used to validate SSULI algorithms that convert raw measurements (Figure 2) into useful environmental parameters that characterize the upper atmosphere.

Software An extensive operational data processing system has been developed to generate environmental data from SSULI spectral data. Spectral data from the LORAAS instrument is also part of this platform. This system, known as the Ground Data Analysis Software (GDAS), includes operational data reduction software using advanced science algorithms also developed at NRL, a customized graphical user interface (GUI), and comprehensive validation techniques. Programs are designed to generate a SSULI Prep file from multiple data sources including Raw Sensor Data Records (RSDR) at the Air Force Weather Agency (AFWA), HIRAAS real-time data assembled at US Space Command, and an extensive HIRAAS infobase on site at the Naval Research Laboratory.

Technical information The sensor has a field-of-view of 2.4°x0.15° and sweeps out a 2.4°x17° field-of-regard during each 90 second scan, with wavelength coverage between 800Å and 1700Å at 23Å resolution. The field of view scans ahead of the spacecraft in the orbital plane through a 17° field of regard, corresponding to approximately 75–750 km altitude.

References

External links Special Sensor Ultraviolet Limb Imager

Illustrations

Worked examples

Example 1 — a first encounter with Special Sensor Ultraviolet Limb Imager

Start with the simplest possible case. Write down what Special Sensor Ultraviolet Limb Imager claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In 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 Special Sensor Ultraviolet Limb Imager 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 Special Sensor Ultraviolet Limb Imager 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 Special Sensor Ultraviolet Limb Imager

In research: Special Sensor Ultraviolet Limb Imager appears in 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 Special Sensor Ultraviolet Limb Imager 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: Special Sensor Ultraviolet Limb Imager is common in secondary-school and first-year university syllabi. It links to neighbouring topics Earth observation satellite sensors, Spectrometers, so understanding it makes those chapters shorter.
In everyday life: Look for Special Sensor Ultraviolet Limb Imager 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 Special Sensor Ultraviolet Limb Imager in 20 minutes

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Frequently asked questions

What is Special Sensor Ultraviolet Limb Imager in simple terms?

Why does Special Sensor Ultraviolet Limb Imager matter?

Because it connects several 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 Special Sensor Ultraviolet Limb Imager?

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 Special Sensor Ultraviolet Limb Imager.