astronomy

STARS-II

STARS-II 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 STARS-II rather than just read about it. In short: Space Tethered Autonomous Robotic Satellite II or STARS-II, was a nanosatellite built by Japan's Kagawa University to test an electrodynamic tether in low Earth orbit, a follow-on to the STARS mission. STARS-II was launched by an H-IIA rocket, flying in the 202 configuration, as a secondary payload aboard the launch of the GPM Core Observatory on 27 February 2014.

Key takeaways

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

Reference excerpt

Space Tethered Autonomous Robotic Satellite II or STARS-II, was a nanosatellite built by Japan's Kagawa University to test an electrodynamic tether in low Earth orbit, a follow-on to the STARS mission. STARS-II was launched by an H-IIA rocket, flying in the 202 configuration, as a secondary payload aboard the launch of the GPM Core Observatory on 27 February 2014. After two months in orbit, STARS-II reentered the atmosphere on 26 April 2014.

Flight Plan The satellite split into two parts, connected by a 300-metre (980 ft) tether, to conduct its experiments which consisted of recording a video of tether deployment and using the tether to deorbit the satellite. The spacecraft consisted of a 5-kilogram (11 lb) base vehicle, with dimensions of 160 by 160 by 253 millimetres (6.3 in × 6.3 in × 10.0 in) and a 4-kilogram (8.8 lb) vehicle at the end of the tether measuring 160 by 160 by 158 millimetres (6.3 in × 6.3 in × 6.2 in). The electrodynamic tether was made from ultra-thin wires of stainless steel and aluminium. One objective of this program was to demonstrate possible technology for de-orbiting space debris.

Results STARS-II was successfully launched at 3:37am (JST) on 28 February 2014 (27 February UTC), and amateur radio downlink showed that it successfully separated from the carrier vehicle, however, the experiment was only partially successful, and tether deployment could not be confirmed. Initial radio data suggested that the solar arrays and antennas were not deployed. The beacon from the daughter spacecraft became weak, and after several weeks was no longer received. It was inferred that solar battery power was low due to its small body. However, the beacon from the mother spacecraft later became strong, and it was inferred that the solar arrays and antennas were deployed by restarting. However, the Command and Data Handling subsystem did not work, possibly due to radiation. The orbit decayed from 350 km to 280 km in 50 days, considerably faster than the other cubesats launched on the same mission, which is indirect indication that the tether deployed, increasing the drag. However, telescopic photography of the satellite from the ground showed the satellite as a single point, rather than two objects. The experimenters suggest that this may have been due to the tether extending, but being tangled by rebound.

Follow-on A follow-on to the STARS and STARS-II satellites, STARS-C (Space Tethered Autonomous Robotic Satellite-Cube, COSPAR 1998-067KR, SATCAT 41895) was announced as a satellite to be launched from the Japanese Experiment Module of the International Space Station. STARS-C was a 2U cubesat consisting of a mother satellite and a daughter satellite, designed to deploy a 100-m aramid fiber tether. It was launched on 9 December 2016, from J-SSOD and re-entered on 3 March 2018. However, the signal quality was intermittent, possibly due to failure of deployment of the solar panel, and data on tether deployment was not obtained. Estimates from orbital drag measurements suggest that the tether deployed to a length of about 30 meters. Also other Japanese STARS satellites have been launched, like STARS-ME, Stars-AO and STARS-EC.

Worked examples

Example 1 — a first encounter with STARS-II

Start with the simplest possible case. Write down what STARS-II 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 STARS-II 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 STARS-II 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 STARS-II

In research: STARS-II 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 STARS-II 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: STARS-II is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2014 in Japan, Satellites of Japan, Secondary payloads, so understanding it makes those chapters shorter.
In everyday life: Look for STARS-II 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “STARS-II” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study STARS-II in 20 minutes

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

Frequently asked questions

What is STARS-II in simple terms?

Why does STARS-II 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 STARS-II?

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 STARS-II.