Space Debris MCQs - Technology

Which material was famously tested by the 'ELSA-d' mission to demonstrate capture of defunct satellites?

Carbon nanotubes
Nylon netting
Adhesive polymers
Magnetic docking plate

Explanation: Astroscale's ELSA-d mission tested the use of magnetic capture to dock with and remove satellites equipped with compatible docking plates.

Which concept uses atmospheric gas to create 'drag sails' that accelerate orbital decay?

Heavy lead ballast
Cold gas thrusters
Thin film membranes
Magnetic coils

Explanation: Deployable drag sails made of thin membranes increase the surface area of a satellite, significantly increasing atmospheric drag and shortening its orbital life.

Which of the following describes 'Active Debris Removal' (ADR)?

Magnetic field shielding
Robotic capture of junk
Self-destruct mechanisms
Natural atmospheric drag

Explanation: ADR involves missions specifically launched to capture and de-orbit large pieces of existing debris using nets, harpoons, or robotic arms.

The term 'COLA' in satellite operations stands for:

Orbital Last Action
Conjunction Level
Coordinate Limit
Collision Avoidance

Explanation: COLA (Collision Avoidance) maneuvers are the active changes in a satellite's path performed to avoid a predicted close approach (conjunction) with debris.

During solar maximum, the concentration of debris at low altitudes (below 600 km) generally decreases because of:

Gravitational shifts
Atmospheric expansion
Magnetic torque
Solar wind pressure

Explanation: Increased solar activity heats and expands the Earth's thermosphere, increasing drag on low-altitude debris and accelerating their re-entry into the atmosphere.

In 'Electrodynamic Tether' de-orbiting, the tether generates current by interacting with which of the following?

Solar photons
Earth's magnetic field
Atmospheric oxygen
Cosmic rays

Explanation: A long conducting tether moving through Earth's magnetic field generates a Lorentz force that acts as drag, slowing the satellite without using propellant.

What happens to the kinetic energy of a debris object when its orbital velocity is doubled?

It stays the same
It triples
It quadruples
It doubles

Explanation: Kinetic energy is proportional to the square of velocity (KE = 1/2 mv²). Doubling the speed increases the energy by a factor of four.

The 'Stardust' mission to remove debris focuses on which capture technique using low-density materials?

Polymer foam
Nylon netting
Aerogel capture
Velcro pads

Explanation: Research into silica aerogel suggests it could be used to safely capture micro-debris without creating further fragmentation upon impact.

The 'Space Sustainability Rating' (SSR) was developed to incentivize companies to:

Design for de-orbiting
Use nuclear propulsion
Reduce satellite mass
Increase launch frequency

Explanation: The SSR, supported by the World Economic Forum, scores missions based on their debris mitigation and responsible orbital behavior.

How many trackable objects (10cm+) are estimated to be currently orbiting Earth as of the mid-2020s?

Over 1,000,000
About 5,000
About 12,000
Over 35,000

Explanation: There are over 35,000 trackable objects, but estimated millions of smaller pieces (1cm and below) that are untrackable but still lethal.

At what approximate velocity do objects in Low Earth Orbit (LEO) typically travel?

3.1 km/s
28.5 km/s
7.8 km/s
11.2 km/s

Explanation: Objects in LEO must travel at roughly 7.8 km/s (approx. 28,000 km/h) to maintain their orbit, giving even tiny fragments massive kinetic energy.

In debris mitigation, 'End-of-Life' passivation requires the discharge of which electrical component to prevent explosions?

Batteries
Transponders
Solar cells
Capacitors

Explanation: Chemical energy stored in batteries can lead to overcharging or thermal runaway years after a mission ends, making electrical discharge a key part of passivation.

What is the 'Threshold of Probability' (typically used by NASA) at which a collision avoidance maneuver is mandated for the ISS?

1 in 100
1 in 100,000
1 in 1,000
1 in 10,000

Explanation: If the probability of a conjunction with the International Space Station is greater than 1 in 10,000, a Debris Avoidance Maneuver (DAM) is typically executed.

Which of the following is a 'Space Situational Awareness' (SSA) sensor that utilizes a liquid-mirror telescope?

GEODSS
ILMT
TIRA
SST

Explanation: The International Liquid Mirror Telescope (ILMT) uses a rotating pool of mercury to scan for space objects, though it is fixed to look only at the zenith.

Which effect describes the slow change in a debris object's semi-major axis caused by the asymmetric emission of thermal radiation?

Lense-Thirring
Coriolis effect
Yarkovsky effect
Poynting-Robertson

Explanation: The Yarkovsky effect involves the force exerted by the emission of photons as heat; it can cause small debris to drift inward or outward over long periods.

The 'Liability Convention' of 1972 holds which entity responsible for damage caused by space debris?

The Insurance Company
The Launching State
The UN Space Office
The Satellite Owner

Explanation: The Convention on International Liability for Damage Caused by Space Objects makes the 'launching state' strictly liable for damage on the surface of the Earth.

What is the primary danger of debris that is too small to be tracked (less than 1 cm)?

Altering the Earth's orbit
Puncturing critical systems
Total satellite destruction
Causing solar eclipses

Explanation: While they may not shatter a satellite, millimeter-sized debris can puncture fuel lines, damage sensors, or degrade solar panels over time.

Which space agency launched the 'ClearSpace-1' mission, the world's first mission to remove an item of debris?

ESA
JAXA
ISRO
NASA

Explanation: The European Space Agency (ESA) commissioned the ClearSpace-1 mission to capture and de-orbit a Vespa payload adapter.

What is the minimum size of a debris object that can currently be tracked from Earth by the U.S. Space Surveillance Network?

10 centimeters
1 millimeter
1 meter
1 centimeter

Explanation: Ground-based radar and optical sensors can reliably track objects about 10 cm and larger in LEO, and roughly 1 meter in higher orbits.

The 'Vespa' object, targeted for removal by ESA, is a specific type of:

Rocket Nozzle
Payload Adapter
Fuel Tank
Small Satellite

Explanation: The Vega Secondary Payload Adapter (Vespa) is an upper stage component from a 2013 launch, chosen as a representative target for removal technology.

What is the primary technical purpose of 'Project West Ford' (1963), which remains a major source of long-lived debris?

ICBM interception
Solar wind mapping
Magnetic shielding
Radio communication

Explanation: Project West Ford placed 480 million copper needles into orbit to create a permanent radio-reflecting belt, many of which clumped together and still orbit Earth.

Which specific altitude range is most densely populated with space debris?

800 - 1000 km
35786 km
200 - 500 km
1500 - 2000 km

Explanation: The 800 to 1000 km altitude range is the most congested due to its historical use for sun-synchronous meteorological and surveillance satellites.

When debris hits a spacecraft at hypervelocity, it can create a plasma cloud that causes which type of electronic failure?

Single Event Upset
Electrostatic Discharge
Frequency Shifting
Magnetic Interference

Explanation: Hypervelocity impacts generate localized plasma that can create conductive paths, leading to an Electrostatic Discharge (ESD) that can short-circuit satellite electronics.

Which of the following describes the 'Mean Time Between Collisions' (MTBC) trend in the current LEO environment?

Increasing linearly
Remaining constant
Exponentially increasing
Decreasing

Explanation: As more satellites are launched and more debris is created, the MTBC is decreasing, meaning collisions are becoming more frequent events.

The 'IADC' is the primary international body coordinating space debris research. What does the 'C' in IADC stand for?

Commission
Consortium
Conference
Committee

Explanation: The Inter-Agency Space Debris Coordination Committee (IADC) is an international governmental forum for the worldwide coordination of activities related to man-made and natural debris.

The 'Graveyard Orbit' is typically located at what altitude relative to the Geosynchronous (GEO) belt?

100 km below GEO
200 km above GEO
300 km above GEO
500 km below GEO

Explanation: Satellites at the end of their life in GEO are moved roughly 300 km higher into a 'super-synchronous' graveyard orbit to clear the valuable GEO belt.

What is the critical 'Impact Velocity' threshold generally required to cause the catastrophic fragmentation of a satellite?

10 km/s
1 km/s
5 km/s
3 km/s

Explanation: While orbits vary, relative velocities above 5 km/s typically ensure that the energy of impact exceeds the structural binding energy, causing complete fragmentation.

A 'Fragmentation Event' is most commonly caused by which of the following?

Explosion of batteries
Solar flare erosion
Natural meteor strikes
Intentional venting

Explanation: Internal energy sources, like leftover fuel or pressurized batteries, are the leading cause of satellite breakups in orbit.

The 2007 Chinese ASAT test targeted which weather satellite, creating one of the largest debris clouds in history?

Shiyan-7
Shenzhou-5
Long March-4
Fengyun-1C

Explanation: The intentional destruction of Fengyun-1C created more than 3,000 pieces of trackable debris and tens of thousands of smaller fragments.

The 'Big Sky Theory' in orbital mechanics was the historical (and now obsolete) belief that:

Gravity clears junk
Space is infinite
Collision risk is zero
Debris burns up

Explanation: The 'Big Sky Theory' argued that space is so vast that the chances of two objects ever hitting each other were negligible, a belief debunked by increasing congestion.

What is the primary orbital characteristic of the 'Molniya' debris class, which makes them difficult to track continuously?

Low inclination
High eccentricity
Equatorial path
Zero velocity

Explanation: Molniya orbits are highly elliptical (eccentric); debris in these orbits spend most of their time at high altitudes and dive quickly through LEO, making tracking inconsistent.

Which technology is being developed by companies like ClearSpace to capture uncooperative debris using a 'tentacle-like' mechanism?

Robotic Arms
Magnetic Harpoon
Net Deployment
Laser Ablation

Explanation: ClearSpace-1 uses four robotic arms (pincers) to grab a defunct payload adapter, ensuring a secure grip on a spinning, uncooperative target.

The 1967 Outer Space Treaty specifies that a state retains jurisdiction and control over an object in space as long as it is:

Within 2000km
In Earth orbit
On the Registry
Functional

Explanation: A state maintains legal ownership and responsibility for a space object indefinitely, regardless of whether it is active or defunct debris, as long as it is registered.

Which Japanese mission tested an electrodynamic tether to slow down and de-orbit space junk?

Ikaros
Akatsuki
Hayabusa-2
Kounotori 6

Explanation: The KITE (Kounotori Integrated Tether Experiment) on the HTV-6 cargo ship attempted to use a tether to generate electricity and drag via Earth's magnetic field.

The term 'Passive Mitigation' in space debris context primarily refers to:

Laser ablation
Using robotic nets
Venting residual fuel
Shielding the satellite

Explanation: Passive mitigation involves 'passivating' the spacecraft by venting leftover fuel or discharging batteries to prevent future accidental explosions.

In the context of GEO disposal, the 'Perigee Increase' formula ($300 + 10.6 imes A/m$) includes the term 'A/m'. What does this term represent?

Altitude per meter
Angle of momentum
Apsis over mass
Area-to-mass ratio

Explanation: The area-to-mass ratio accounts for the effect of solar radiation pressure; high area-to-mass objects require a higher graveyard orbit to ensure they don't drift back.

The theoretical phenomenon where the density of objects in LEO is high enough that collisions create a self-sustaining cascade is known as:

Cascading Failure
Delta-v Overload
Orbital Congestion
Kessler Syndrome

Explanation: Proposed by Donald Kessler in 1978, this scenario suggests that the accumulation of space junk could eventually make certain orbital planes unusable for generations.

What is the primary function of a 'Whipple Shield' on a spacecraft?

Capture microsatellites
Absorb heat during re-entry
Fragment small debris impacts
Deflect solar radiation

Explanation: A Whipple shield uses a thin outer layer to break up a small piece of debris into a cloud of even smaller particles before they hit the main hull.

What is the primary cause of 'orbital decay' for satellites in very low Earth orbit (below 400 km)?

Gravitational waves
Solar wind pressure
Atmospheric drag
Magnetic torque

Explanation: Even at 400 km, there is a trace atmosphere that creates drag, causing objects to lose speed and eventually fall back to Earth.

Which 1978 event involved a Soviet satellite's nuclear reactor re-entering over Canada, causing debris concerns?

Soyuz 11
Cosmos 954
Vostok 1
Salyut 6

Explanation: The re-entry of Cosmos 954 scattered radioactive debris over northern Canada, highlighting the risks of complex debris components.

Which of the following is a primary reason that 'CubeSats' are criticized in debris management discussions?

Lack of propulsion
Reflective coating
Complex electronics
High orbital mass

Explanation: Many CubeSats lack propulsion systems, meaning they cannot perform collision avoidance or actively de-orbit, relying solely on natural decay.

In space debris metrology, the 'Ballistic Coefficient' is a crucial parameter used primarily to predict:

Fragmentation count
Atmospheric decay
Kinetic energy
Collision probability

Explanation: The ballistic coefficient (mass divided by the product of drag coefficient and area) determines how much atmospheric drag affects an object’s orbital lifespan.

The first confirmed accidental collision between two man-made objects involved the French satellite 'Cerise' and a fragment from which rocket?

Ariane 1
Proton-M
Delta II
Long March 2

Explanation: In 1996, the Cerise satellite’s gravity-gradient stabilization boom was struck by a fragment from an Ariane 1 rocket upper stage that had exploded ten years earlier.

The 'ORDEM' model used by NASA for debris environment projection stands for:

Orbital Debris Model
Orbital Range Data
Outer Rim Debris
Object Recovery Data

Explanation: The Orbital Debris Engineering Model (ORDEM) is NASA’s primary software tool for estimating the debris population and risk in Earth's orbit.

The 'RemoveDEBRIS' mission successfully tested which capture mechanism in 2018?

Electro-static tug
Sticky boom
Laser beam
Harpoon and Net

Explanation: The RemoveDEBRIS satellite successfully deployed a net to capture a simulated target and fired a harpoon at a structural panel.

Which of the following materials is typically used for 'Nextel' layers in a Multi-Shock Shield for debris protection?

Kevlar
Ceramic fabric
Carbon fiber
High-grade steel

Explanation: Nextel is a ceramic fabric used in advanced Whipple shields; it is highly effective at shocking and vaporizing debris particles upon impact.

Which specific coolant was released in thousands of droplets by Soviet RORSAT satellites, contributing to debris in the 700-1000 km range?

Sodium-Potassium
Hydrazine
Ammonia-Water
Liquid Nitrogen

Explanation: Soviet Radar Ocean Reconnaissance Satellites (RORSATs) ejected their reactor cores at the end of life, releasing NaK (Sodium-Potassium) coolant droplets that remain in orbit today.

Which S-band radar system, located at Kwajalein Atoll, is capable of tracking sub-centimeter debris as part of the 'Space Fence'?

AN/FSY-3
AN/FPS-85
AN/FPS-133
AN/SPY-1

Explanation: The Lockheed Martin-built 'Space Fence' (AN/FSY-3) provides high-frequency S-band radar surveillance to track much smaller objects than traditional L-band systems.

The 1972 Liability Convention distinguishes between damage in space and on Earth. For damage in space, liability is based on:

No liability
Fault-based liability
Absolute liability
Shared liability

Explanation: For collisions in space, the convention requires proof of fault. Conversely, for damage on the Earth's surface, the launching state is 'absolutely' liable.

Which international treaty is the foundation of space law, though it lacks specific rules on debris mitigation?

Liability Convention
Registration Convention
Moon Agreement
Outer Space Treaty

Explanation: The 1967 Outer Space Treaty provides the basic framework for space activities, emphasizing that space should be used for peaceful purposes.

What is the primary technical challenge of using a 'Laser Broom' to clear space debris?

Photon pressure is too low
High power requirements
Laser beam dispersion
Atmospheric interference

Explanation: Ground-based lasers suffer from atmospheric distortion, making it difficult to maintain the beam focus required to vaporize debris surfaces.

Which 2009 event marked the first ever hypervelocity collision between two intact satellites?

Fengyun-Starlink impact
Vanguard-Sputnik crash
Telstar-Molniya event
Iridium-Cosmos collision

Explanation: The collision between the active Iridium 33 and the defunct Cosmos 2251 created over 2,000 pieces of trackable debris in LEO.

In the context of debris, what does 'Passivation' involve?

Lowering the orbit
Using a solar sail
Painting the satellite white
Removing energy sources

Explanation: Passivation is the process of removing any stored energy (chemical, electrical, or kinetic) to prevent an explosion after the mission ends.

Which of the following is an example of an 'end-of-life' disposal maneuver for a LEO satellite?

Nuclear vaporization
Controlled re-entry
Solar sailing away
Gravity assist to Moon

Explanation: Controlled re-entry uses the remaining fuel to push the satellite into the atmosphere over an unpopulated area (like the South Pacific) to burn up.

The IADC guidelines suggest that satellites should naturally de-orbit within how many years after mission completion?

10 years
100 years
25 years
50 years

Explanation: The Inter-Agency Space Debris Coordination Committee (IADC) '25-year rule' is the international standard for post-mission disposal in LEO.

The 'Space Sustainability Rating' (SSR) uses a composite score to evaluate a mission's 'Orbital Footprint'. This footprint is a measure of:

Satellite volume
Launch emissions
Fuel efficiency
Risk of collision

Explanation: The Orbital Footprint measures how much space a satellite 'occupies' in terms of its size, altitude, and probability of colliding with other objects over its lifetime.

The 'United Nations Office for Outer Space Affairs' (UNOOSA) maintains which important record?

Space Weather Alert
Register of Objects
Satellite Price Index
Astronaut Hall of Fame

Explanation: UNOOSA maintains the Register of Objects Launched into Outer Space to identify which state is responsible for each satellite.

Which of the following describes the 'Bumper' in a Whipple shield configuration?

The main satellite wall
The sacrificial outer layer
The thermal insulation
The internal fuel lining

Explanation: The 'Bumper' is the thin outer plate placed at a distance from the main wall; its job is to break up the projectile before it reaches the main structure.

What is the primary reason that debris observation in GEO is conducted predominantly via optical telescopes rather than radar?

Low object mass
Signal propagation delay
Atmospheric absorption
Inverse-fourth-law loss

Explanation: Radar power drops off according to the inverse fourth power of the distance ($1/r^4$), making it extremely power-intensive to detect small objects at 36,000 km.

Which radar system is the primary European tool for tracking and surveillance of space objects?

GRAVES
Globus II
PAVE PAWS
Haystack

Explanation: The GRAVES radar (Grand Réseau Adapté à la Veille Spatiale) is a French system used to track and catalog objects in orbit over Europe.

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