astronomy

MINERVA (spacecraft)

MINERVA (spacecraft) 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 MINERVA (spacecraft) rather than just read about it. In short: MINERVA (MIcro-Nano Experimental Robot Vehicle for Asteroid) are a series of rovers developed by the Japanese space agency JAXA for the purpose of exploring asteroid surfaces. The first MINERVA was part of the Hayabusa mission, while MINERVA-II was a series of three rovers for its successor, Hayabusa2.

Key takeaways

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

Reference excerpt

MINERVA (MIcro-Nano Experimental Robot Vehicle for Asteroid) are a series of rovers developed by the Japanese space agency JAXA for the purpose of exploring asteroid surfaces. The first MINERVA was part of the Hayabusa mission, while MINERVA-II was a series of three rovers for its successor, Hayabusa2. On 12 November 2005, MINERVA was deployed from Hayabusa with the aim of landing on asteroid 25143 Itokawa. However, the landing failed as MINERVA missed the asteroid and ended up in a heliocentric orbit. On 21 September 2018, two MINERVA-II rovers successfully landed on asteroid 162173 Ryugu. The third MINERVA-II rover malfunctioned before it could be deployed, but was released anyway on 2 October 2019 to perform gravitational measurements before impacting the asteroid a few days later.

Overview

Following the approval of the asteroid sample-return project MUSES-C, a rover was proposed to be mounted on the asteroid explorer, and development of MINERVA began in 1997. Completed in February 2003, MINERVA was Japan's first space rover, and the first asteroid rover in the world. On 9 May 2003, the MUSES-C spacecraft carrying MINERVA was launched from Kagoshima Space Center, and was named Hayabusa. Hayabusa arrived at its target, asteroid 25143 Itokawa, on 12 September 2005. After a two-month long observation phase, Hayabusa began descent rehearsals in preparation for its asteroid landings. On 12 November, MINERVA was separated from Hayabusa and headed for Itokawa, but the drop failed and thus MINERVA became the smallest artificial object in heliocentric orbit. Following separation MINERVA continued to communicate for 18 hours, transmitting data to its mothership. After Hayabusa's return to Earth, a successor project, Hayabusa2, began, which also included a rover. While MINERVA was treated as an optional addition in the first Hayabusa, MINERVA-II became part of the nominal payload for Hayabusa2. Launched on 3 December 2014, Hayabusa2 arrived at asteroid 162173 Ryugu on 27 June 2018. MINERVA-II-1, composed of two identical rovers, was deployed from Hayabusa2 in 21 September. Both rovers reached Ryugu's surface, and became the first probes ever to travel the surface of an asteroid. JAXA announced that the rovers have been named HIBOU (previously Rover-1A) and OWL (previously Rover-1B), respectively. Hibou [i.bu] is the French word for 'owl'. The second rover deployment for MINERVA-II-2 happened 2 October 2019 16:38 UTC. The rover, known as Rover-2 or MINERVA-II-2 failed before deployment, but was released from the Hayabusa2 orbiter anyway to perform gravitational measurements. It impacted the asteroid a few days after release on 8 October.

Design

MINERVA

MINERVA consists of five components, including the rover's body.

OME-B, which mounts MINERVA to MUSES-C, and supplies power to MINERVA until its separation OME-C, the cover between OME-B and MUSES-C OME-E, the repeater between the mothership's data bus OME-Ant, a flat patch antenna for OME-E to communicate with MINERVA These four components were inside the rover. MINERVA itself is a hexadecagonal prism with a diameter of 12 cm and a height of 10 cm, with solar cells attached to each side. This allows the probe to secure power in any attitude as long as it was in a sunlit environment. For shock mitigation during landing and to protect the solar cells, 16 pins are protruding from MINERVA's surface. Six among them had thermometers inside them to directly measure the asteroid's ground temperature. The pins also functioned as a means to increase friction during the hops. Power is supplied from the solar cells attached to every side of MINERVA. Surplus power gets stored in an electric double-layer capacitor, and is used in situations that requires greater power than what gets generated by the solar cells, such as rotating the motor and when using the cameras. After the electric double-layer capacitor ceases function, communication will still be possible but the rover will be unable to make further hops or imaging, so an operation was considered to have a stationary MINERVA continuously measure the asteroid surface temperature of its final resting place. Along with six built-in temperature sensors at the pins sticking out from the main body, MINERVA had three cameras and six photodiodes on board as external sensors. The three CCD cameras were identical; two of them faced the same direction and were adjacent with each other, enabling closeup stereographic imaging. This was intended for mainly shooting the asteroid surface. The remaining camera was placed on the opposite side of the two cameras, with the primary purpose of imaging the asteroid from above during the hops. On MINERVA's topside and underside an antenna is located. As the rover's attitude shifts, the either side facing Hayabusa was to be used. The communication speed between MINERVA and OME-E was 9.6 kbps, with a maximum range of 20 km. MINERVA has an on-board microcomputer. Its main CPU microprocessor is Hitachi's SH-3, clocked at 10 MHz, adopted for its low power consumption, performance efficiency and reliability. The computer's memory includes 2 MB RAM, 512 KB ROM, and 2 MB Flash ROM.

MINERVA-II-1

MINERVA-II-1 was developed by JAXA and the University of Aizu. It has a slim design compared to its predecessor, to increase the likelihood the surface with larger area would contact the asteroid surface. MINERVA-II-1 was enlarged from its predecessor as the rover's destination, asteroid Ryugu was more distant from the Sun than Itokawa, necessitating an increase in solar cell area. Ryugu's greater size compared to Itokawa means rovers will face stronger gravity, thus larger DC motors are used for MINERVA-II-1. By deploying two rovers simultaneously, a network of space probes can be achieved. The maximum communication speed between the MINERVA-II-1 rovers and the mothership's OME-E is 32 kbps. The two rovers are nearly identical, the only difference being some internal sensors and the thermal characteristics. Rover-1A uses a traditional multi-layer insulation, which covers the rover to prevent heat from entering, while Rover-1B is equipped with radiators to dissipate heat to the outside.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with MINERVA (spacecraft)

Start with the simplest possible case. Write down what MINERVA (spacecraft) 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 MINERVA (spacecraft) 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 MINERVA (spacecraft) 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 MINERVA (spacecraft)

In research: MINERVA (spacecraft) 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 MINERVA (spacecraft) 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: MINERVA (spacecraft) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Attached spacecraft, Hopping spacecraft, Japanese space probes, so understanding it makes those chapters shorter.
In everyday life: Look for MINERVA (spacecraft) 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 MINERVA (spacecraft) in 20 minutes

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

Frequently asked questions

What is MINERVA (spacecraft) in simple terms?

Why does MINERVA (spacecraft) 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 MINERVA (spacecraft)?

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 MINERVA (spacecraft).