astronomy

Ikonos

Ikonos is a astronomy 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 Ikonos rather than just read about it. In short: IKONOS was a commercial Earth observation satellite, and was the first to collect publicly available high-resolution imagery at 1- and 4-meter resolution. It collected multispectral (MS) and panchromatic (PAN) imagery.

Key takeaways

Ikonos belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Ikonos to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Ikonos from memory before moving on to harder problems.

Reference excerpt

IKONOS was a commercial Earth observation satellite, and was the first to collect publicly available high-resolution imagery at 1- and 4-meter resolution. It collected multispectral (MS) and panchromatic (PAN) imagery. The capability to observe Earth via space-based telescope has been called "one of the most significant developments in the history of the space age", and IKONOS brought imagery rivaling that of military spy satellites to the commercial market. IKONOS imagery began being sold on 1 January 2000, and the spacecraft was retired in 2015.

History IKONOS originated under the Lockheed Corporation as the Commercial Remote Sensing System (CRSS) satellite. In April 1994 Lockheed was granted one of the first licenses from the U.S. Department of Commerce for commercial satellite high-resolution imagery. On 25 October 1995 partner company Space Imaging received a license from the Federal Communications Commission (FCC) to transmit telemetry from the satellite in the eight-gigahertz Earth exploration-satellite services band. Prior to launch, Space Imaging changed the name of the satellite system to IKONOS. The name comes from the Greek word eikōn, for "image". Two satellites were originally planned for operation. IKONOS-1 was launched on 27 April 1999 at 18:22 UTC from Vandenberg AFB Space Launch Complex 6, but Athena II rocket's payload fairing did not separate due to an electrical malfunction, resulting in the satellite failing to reach orbit and falling into the atmosphere over the South Pacific Ocean. IKONOS-2 was built in parallel with and as a nearly identical twin to IKONOS-1. Whereas IKONOS-1 was built with Ring Laser Gyros (RLGs) for attitude rate sensors, IKONOS-2 fortuitously was built with Hemispherical Resonator Gyros (HRGs). RLGs were found to be incompatible with long-duration space missions, whereas HRGs could last 10 or more years in space. Completion of IKONOS-2 construction was projected for July 1999 with a January 2000 launch. In reaction to the loss of IKONOS-1, the spacecraft was renamed IKONOS and its processing accelerated, resulting in a launch on 24 September 1999 at 18:22 UTC, also from Vandenberg aboard an Athena II rocket. The company began selling IKONOS imagery on the market on 1 January 2000. In December 2000, IKONOS received the "Best of What's New" Grant Award in Aviation & Space from Popular Science magazine. The acquisition of Space Imaging and its assets by Orbimage was announced in September 2005 and finalized in January 2006. The merged company was renamed GeoEye, which was itself acquired by DigitalGlobe in January 2013. DigitalGlobe operated IKONOS until its retirement on 31 March 2015. During its lifetime, IKONOS produced 597,802 public images, covering more than 400 million km2 (154 million sq mi) of area.

Specifications

Spacecraft IKONOS was a three-axis stabilized spacecraft designed by Lockheed Martin Space Systems. The design later became known as the LM-900 satellite bus and was optimized to carry remote sensing payloads. Four reaction wheels stabilized the spacecraft's altitude, which was measured by two star trackers and a Sun sensor. Orbital position information was provided by a GPS receiver. The spacecraft body was a hexagonal design of 1.83 by 1.57 meters (6.0 by 5.2 ft) and 817 kilograms (1,800 lb), with 1.5 kilowatts of power provided by three solar panels. Its design life was seven years. IKONOS operated in a Sun-synchronous, near-polar, circular orbit at approximately 680 km (423 mi).

Optical Sensor Assembly IKONOS's primary instrument was the Optical Sensor Assembly (OSA), designed and built by Kodak. It had a primary mirror aperture of 70 cm (28 in), and a folded optical focal length of 10 m (394 in) using 5 mirrors. The main mirror featured a honeycomb design to reduce mass. The detectors at the focal plane included a panchromatic sensor with 13,500 pixels cross-track, and four multispectral sensors (blue, green, red, and near-infrared) each with 3,375 pixels along-track. Its nadir image swath was 11.3 km (7 mi). Total instrument mass was 171 kg (377 lb) and it consumed 350 watts.

Worked examples

Example 1 — a first encounter with Ikonos

Start with the simplest possible case. Write down what Ikonos claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 Ikonos 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 Ikonos 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 Ikonos

In research: Ikonos appears in astronomy 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 Ikonos 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: Ikonos is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2015 disestablishments in the United States, Commercial imaging satellites of the United States, Derelict satellites orbiting Earth, so understanding it makes those chapters shorter.
In everyday life: Look for Ikonos 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 Ikonos in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Ikonos 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.
Explain Ikonos out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Ikonos in simple terms?

Why does Ikonos matter?

Because it connects several astronomy 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 Ikonos?

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 Ikonos.