patrickfleith/astro-mcq huggingface dataset:
True or False? An object that is not accelerating or decelerating has no forces acting on it.

A. True
B. False
C. Impossible to say without more information

Answer: B. False
Complete the following: During its orbital period, as a planet moves farther away from the sun, the orbital velocity of the planet ...

A. increases
B. decreases
C. remains the same

Answer: B. decreases
Which affirmation is true when talking about Earth’s potential energy?

A. The potential energy is positive
B. None of the above answers
C. The potential energy is negative
D. The potential energy is constant

Answer: C. The potential energy is negative
Why do we talk about microgravity in LEO?

A. The free-fall trajectory gets perturbed
B. None of the above answers
C. In LEO orbits, the Earth’s gravity is not exactly zero
D. All the external forces are not cancelling exactly

Answer: A. The free-fall trajectory gets perturbed
To what wavelength is the atmosphere the most transparent?

A. Infra Red
B. X-rays
C. Radio Waves
D. Visible light

Answer: C. Radio Waves
In the atmosphere and space environment, what best describes the so-called airglow?

A. Photo ionization of oxygen
B. Photo Ionization of Hydrogen
C. Northern lights
D. Diffraction of the Sun light in the upper layers of the atmosphere

Answer: A. Photo ionization of oxygen
A rocket is launched from ESA spaceport in Kourou, French Guyana. Through which layers of the atmosphere and in what order the rocket will pass through?

A. troposphere, mesosphere, stratosphere, thermosphere
B. troposphere, mesosphere, thermosphere, stratosphere
C. troposphere, stratosphere, mesosphere, thermosphere
D. thermosphere, troposphere, stratosphere, mesosphere

Answer: C. troposphere, stratosphere, mesosphere, thermosphere
What are the Van Allen belts?

A. Low radiation regions
B. The region between 90 and 100 km altitude
C. Radiation belts
D. Much used orbits for telecommunication

Answer: C. Radiation belts
Why is the inner radiation belt harmful for satellites, and more so than the outer belt ?

A. the question is not correct, the outer belt is more harmful for satellites.
B. Inner radiation traps protons which are more likely to damage on-board electronics.
C. Inner radiation traps space debris which damage the structure of satellites.
D. Inner radiation modify the magnetic field and will damage optical system of satellites.

Answer: B. Inner radiation traps protons which are more likely to damage on-board electronics.
The sunspot number is a value that changes with time, with a period of approximately...

A. 9 years
B. 13 years
C. 7 years
D. 11 years

Answer: D. 11 years
Which of the following statement(s) is or are correct(s) with respect to the solar cycle effect on satellite lifetime at a given altitude?

A. At solar maximum, you have lower atmosphere density, which means less drag, and and increased satellite lifetime
B. At solar minimum, you have lower atmosphere density, when means less lift for the satellite, and reduced lifetime
C. At solar maximum, you have higher atmosphere density, which means more drag, and reduced satellite lifetime
D. At solar minimum, you have higher atmosphere density, which means more radiation, and reduced satellite lifetime

Answer: C. At solar maximum, you have higher atmosphere density, which means more drag, and reduced satellite lifetime
Based on your understanding of the solar cycle, where would be the best place to see auroras? (select all that apply)

A. Near the equator
B. Close to Antarctic and Arctic circles
C. Iceland or northern Scandinavia
D. Latin America

Answer: B. Close to Antarctic and Arctic circles
C. Iceland or northern Scandinavia
What would be the most appropriate time to observe auroras?

A. 2023
B. 2018
C. 2029
D. anytime

Answer: A. 2023
What is the main driver of the shape of solar prominences ?

A. Magnetic fields generated by the sun
B. Van Allen radiation belts
C. The orbital forces of Mercury
D. Earth

Answer: A. Magnetic fields generated by the sun
What is the difference between CMEs (Coronal Mass Ejections) and prominences ?

A. There is no difference
B. CMEs are only caused by radiation belt
C. CMEs do not reconnect towards the sun. They also emit in lower wave-lengths.
D. Prominences and CMEs appear at different times of the day

Answer: C. CMEs do not reconnect towards the sun. They also emit in lower wave-lengths.
What is the typical lower boundary of the Van Allen belts?

A. 200-300 km, roughly the altitude of the Hubble Space Telescope
B. Half-way to the Moon
C. Below the ISS altitude
D. 500-600 km, roughly the altitude of the Hubble Space Telescope

Answer: D. 500-600 km, roughly the altitude of the Hubble Space Telescope
What is the global shape of the Earth radiation belts?

A. Spherical
B. Triangular
C. Toroidal
D. Rectangular

Answer: C. Toroidal
What is the sectional profile of the Earth radiation belts?

A. Banana-shaped, with the extremities close to the surface of the Earth
B. Rectangular
C. Disk
D. Banana-shaped, with the extremities away from the Earth

Answer: A. Banana-shaped, with the extremities close to the surface of the Earth
The activity of the Sun has a periodicity of 11 years. What are the methods to observe it? (Select all that apply)

A. Measure the Sun's flux in a spectral band called H-alpha
B. Measure the Sun's flux at a wavelength of 10.7 cm
C. Measure the Sun's bolometric flux (i.e. the flux over the whole spectrum)
D. Count the number of sun spots

Answer: B. Measure the Sun's flux at a wavelength of 10.7 cm
D. Count the number of sun spots
The solar prominence are bright features extending far into space. They can last from a few dozen hours to months. What can be their size?

A. Up to the distance from the Sun to Earth
B. A siginificant fraction of the Sun's radius
C. Up to the distance from the Sun to Mercury
D. Up to the size of the Earth

Answer: D. Up to the size of the Earth
Coronal Mass Ejections (CMEs) are huge ejections of plasma from the Sun. What is their manifestation at a far distance (e.g. somewhere in the vicinity of Earth) from the Sun?

A. The Sun darkens from the observer point of view
B. None, it's too far away
C. A gust of charged particles
D. The flux of light from the Sun is lowered.

Answer: C. A gust of charged particles
What is the magnetosphere?

A. A region in Indonesia
B. A spherical object composed solely of magnetic material
C. A region that surrounds an object that has a magnetic field, usually a dipole which is distored by charged particles
D. A region that surrounds an object that has a magnetic field, which tunnels neutral particles away from the object

Answer: C. A region that surrounds an object that has a magnetic field, usually a dipole which is distored by charged particles
Some of the solar flux is reflected off the surface of the Earth. The fraction of sunlight reflected is given by the albedo. If the albedo increases, how will the amount of reflected light change?

A. It descreases
B. Impossible to say, we need more information to answer
C. It stays the same
D. It increases

Answer: D. It increases
Crossing the South Atlantic Anomaly (SAA) with a satellite can greatly restrict its performance. Why?

A. The SAA is a region of permanent shadow over the South Atlantic, thus there is no power generated by the solar panels.
B. The SAA is a region of extremely high radiation. Radiations create errors in the onboard electronics which can potentially be permanent.
C. The SAA is a region which is not covered by any array of antenna, which renders any communication between the ground and the satellite impossible.
D. The SAA is a region of extremely low radiation. This induces large currents in the onboard electronics which degrades the performance.

Answer: B. The SAA is a region of extremely high radiation. Radiations create errors in the onboard electronics which can potentially be permanent.
An object X and an object Y are in orbit (at the same altitude). X has a Drag Coefficient of 2 while Y has a drag Coefficient of 2.2. Which object will first fall back to Earth?

A. Impossible to say
B. Object Y
C. Both at the same time
D. Object X

Answer: A. Impossible to say
Space debris mitigation rule states that after end of nominal operations, a satellite has to fall back to Earth or to be put on a graveyard orbit within

A. 25 years
B. 24 years
C. 42 years
D. 23 years

Answer: A. 25 years
Hubble's solar arrays were damaged because of collisions with:

A. The famous cosmos-irridium breakup that destroyed the primary mirror of the telescope
B. Meteorites with a 10e-5 cm diameter
C. Orbital debris
D. Meteorites with a 10e-2 cm diameter
E. Meteroites with a 10 cm diameter

Answer: B. Meteorites with a 10e-5 cm diameter
C. Orbital debris
D. Meteorites with a 10e-2 cm diameter
The International Space Station (ISS) is placed on an elliptical orbit around the Earth. The orbital apogee is 417 km and orbital perigee is 401 km. What is the gravitational acceleration created by the Earth at the orbit perigee?

A. 8.68 m/s^2
B. 1.72 m/s^2
C. 7.78 m/s^2
D. 0 m/s^2

Answer: A. 8.68 m/s^2
What is the escape velocity from the surface of the moon Europa (mass M = 4.8e22 kg, radius 1560 km)? (answer in km/s)

A. Approximately 4
B. Approximately 2
C. Approximately 3
D. Approximately 1
E. Approximately 5

Answer: B. Approximately 2
The escape velocity out of the solar system from Jupiter's orbit is 18.5 km/s while the average orbital velocity is 13.1 km/s. What is the transfer velocity in km/s?

A. 5.4
B. 3.6
C. 1.4
D. 2.7
E. 0.2

Answer: A. 5.4
The comet 67P/Churyumov-Gerasimenko has an escape velocity close to 1 m/s. What would be sufficient in the following to escape its surface and never come back ?

A. You, by jumping the equivalent of 50 cm on Earth.
B. A bullet shot by a pistol.
C. None of the above.
D. A tennis ball hit by Roger Federer.

Answer: A. You, by jumping the equivalent of 50 cm on Earth.
B. A bullet shot by a pistol.
D. A tennis ball hit by Roger Federer.
The Rosetta spacecraft launched by the European Space Agency successfully entered the orbit of the comet 67P/Churyumov-Gerasimenko in August 2014. November 12 2014, the Philae lander was released and touched down 7 hours later at a speed of 0.98m/s. The harpoon mechanism which was supposed to secure the lander failed and it bounced off the comet. Assuming purely elastic impact, will the lander leave the comet or return at some point?

A. The lander's chances are fair, but there is a significant risk.
B. All is good, not to worry, Philae will come down for sure.
C. For sure, the lander is lost.

Answer: A. The lander's chances are fair, but there is a significant risk.
Telecommunications satellites are often on geostationary orbits (GEO) at an altitude of 35786 km above the surface of the Earth. What is the Earth escape velocity from that orbit? (answer in km/s)

A. 5.6
B. 5.0
C. 4.7
D. 5.3
E. 5.9

Answer: C. 4.7
Which formula gives the work to be performed in order to bring a unit mass from the Earth's surface to infinity? Assume that g0 is the standard gravitational acceleration for the surface of the Earth, R is the radius of the Earth, and p the atmospheric pressure.

A. g0 * R * p
B. g0 * R
C. g0 * R^2
D. g0 * R * p^2

Answer: B. g0 * R
What is the formula to compute the escape velocity given mu (standard gravitational parameter), and r (the distance to the center of the central body)?

A. V = sqrt( mu / 2r )
B. V = sqrt( 2 * mu / r )
C. V = sqrt( 2 * mu / r^3 )
D. V = sqrt( mu / r )
E. V = mu * r

Answer: B. V = sqrt( 2 * mu / r )
The gravitational acceleration at the altitude of the ISS is about 8.68 m/s. However, the astronauts onboard the station are in weightlessness. Why?

A. The ISS is constantly rotating around its main axis, creating the illusion of weightlessness.
B. The ISS is constanly falling towards the Earth, but with enough horizontal speed to create an opposing acceleration and equal in magnitude to the gravitational acceleration.
C. Thrusters are in constant use which generate a force such that there is weightlessness.
D. None of the above.

Answer: B. The ISS is constanly falling towards the Earth, but with enough horizontal speed to create an opposing acceleration and equal in magnitude to the gravitational acceleration.
A spacecraft is on a free trajectory in the vicinity of the Earth. From which statement can it be deduced that this spacecraft has sufficient energy to leave Earth's gravitational well (i.e. it is not on orbit around the Earth)? Assumption: Etot refers to the total energy of the spacecraft.

A. Etot is close to + infinity
B. Etot < 0
C. Etot >= 0
D. Etot is close to - infinity

Answer: C. Etot >= 0
The transfer velocity from an 1 AU orbit (i.e. Earth's orbit) is about 12 km/s. The transfer velocity from Mercury's orbit is 20 km/s. A probe is on an 1 AU orbit with the objective of going towards Mercury. What action must be taken?

A. Increase the velocity by 12 km/s.
B. Decrease the energy of the probe.
C. Wait until the orbit is perturbed enough to flyby Mercury.
D. Increase the energy of the probe.

Answer: B. Decrease the energy of the probe.
What is the orbital velocity of the Hubble Space Telescope which is on a circular orbit at 555 km altitude? (answer in km/s)

A. 7.58
B. 6.21
C. 8.02
D. 4.00

Answer: A. 7.58
What is the strength of the Earth’s acceleration in LEO?

A. 10% of the acceleration on the surface of the Earth
B. 90% of the acceleration on the surface of the Earth
C. No acceleration, that’s why you can float in space
D. Same acceleration than on the surface of the Earth

Answer: B. 90% of the acceleration on the surface of the Earth
Which of the following proportionnality relation with the orbital period T with respect to the semi-major axis a is correct?

A. T is proportional to a
B. T^2 is proportional to a
C. T is proportional to a^(3/2)
D. T^2 is proportional to a^2

Answer: C. T is proportional to a^(3/2)
An artificial Earth satellite is in an elliptical orbit with a perigee altitude of hp = 250 km and an apogee altitude of ha = 800 km. What is the correct expression of the orbital period?

A. T = 2*pi * sqrt( a^2 / mu )
B. T = 2*pi * sqrt( a^3 / mu )
C. T = 2*pi * a^3 / mu
D. T = 2*pi * sqrt( a^(1/2) / mu )

Answer: B. T = 2*pi * sqrt( a^3 / mu )
An artificial Earth satellite is in an elliptical orbit with a perigee altitude of hp and an apogee altitude of ha. How do you express the semi major of the axis of the satellite orbit "a"  in function of hp, ha, and R where R is the Earth's radius?

A. a = R ( hp + ha ) / 2
B. a = R ( ha - hp ) / 2
C. a = R + (ha + hp) / 2
D. a = 2R + (ha + hp) / 2
E. a = R - (hp + ha) / 2

Answer: C. a = R + (ha + hp) / 2
An artificial Earth satellite is in an elliptical orbit with a perigee altitude of hp = 250 km and an apogee altitude of ha = 800 km. What is its orbital period expressed in minutes?

A. 100.9
B. 18.0
C. 95.0
D. 89.5

Answer: C. 95.0
A geostationary orbit is defined as an orbit were the satellite is always pointing towards the same point on the Earth's surface. What is its eccentricity?

A. 1
B. 0
C. 1.3
D. 0.5

Answer: B. 0
A geostationary orbit is defined as an orbit were the satellite is always pointing towards the same point on the Earth's surface. What is its inclination?

A. 0°
B. 7.01°
C. 3.2°
D. 45°

Answer: A. 0°
In orbital mechanics, what is the meaning of the mean motion n = sqrt( mu / a^3 )?

A. In the specific case where the eccentricity e tends to zero, the mean motion and the true anomaly tend to be equal.
B. The mean motion relates to the true position of a body moving along a Keplerian orbit.
C. It corresponds to the instantaneous angular rate for a non-circular orbit.
D. It can be defined only for parabolic orbits.
E. It is the average angular rate over one full orbit, in rad/s

Answer: E. It is the average angular rate over one full orbit, in rad/s
What reference frame is the best suited for an interplanetary probe?

A. Geographic coordinate system
B. Geo-centric coordinate system
C. Heliocentric-inertial coordinate system

Answer: C. Heliocentric-inertial coordinate system
The complete precessional cycle of the Earth lasts about 26000 years. What is the precession rate? (in degrees per year)

A. 0.00384
B. 0.05384
C. 0.01384
D. 0.02384
E. 0.04384
F. 0.03384

Answer: C. 0.01384
What is the RAAN?

A. The time of the periapsis transit.
B. The angle from a reference direction to the point where the satellite crosses the plane of reference, towards the south.
C. The angle from a reference direction to the point where the satellite crosses the plane of reference, towards the north.
D. The inclination of the orbital plane.

Answer: C. The angle from a reference direction to the point where the satellite crosses the plane of reference, towards the north.
How long is a sideral day?

A. 24h04min
B. 23h56min
C. 11h56min
D. 24h00min

Answer: B. 23h56min
Where is an orbital maneuver Delta-V adding energy to a spacecraft on orbit best performed?

A. Along the orbital velocity
B. Any direction of the Delta-V vector will add energy to the spacectaft on orbit.
C. Along the orbit angular momentum
D. Radially

Answer: A. Along the orbital velocity
What is the Hohmann transfer for small Delta-V useful for?

A. Interplanetary trajectories
B. Orbital rendez-vous
C. Earth-Moon transfer
D. Manoeuvers around small bodies (e.g. comets)

Answer: B. Orbital rendez-vous
Where is the Delta-V for an inclination change smaller?

A. at low altitudes
B. at the poles
C. at the equator
D. at high altitudes

Answer: D. at high altitudes
What is the difference between geostationary and geosynchronous orbits?

A. Geostationary has an orbital period of 24h whereas geosynchronous orbits is 23h56
B. All of the above
C. A geosynchronous satellite orbits the same location over Earth's surface while a geostationary satellite remains on average at the equator
D. The orbital parameters for geostationary are inclination = 0° and eccentricity = 0

Answer: D. The orbital parameters for geostationary are inclination = 0° and eccentricity = 0
The ground tracks for a satellite in LEO (typical orbital period is 90 min) is shifting to the west from one equator crossing to the next. What is the typical value of the shift in degrees?

A. 22.5
B. 15
C. 12.5
D. 20
E. 17.5

Answer: A. 22.5
Among the following assertion about Lagrange points, which one is true?

A. The distance between the Lagrange points and the Earth varies drastically with the seasons
B. The Sun-Earth system does not have any Lagrange points because of the Moon
C. The Lagrange points orbit the Sun with the same orbital period as the Earth's
D. None of the above

Answer: C. The Lagrange points orbit the Sun with the same orbital period as the Earth's
A spacecraft is below and behind the ISS, both are on circular orbits. What will happen to their relative position?

A. The spacecraft will overtake the ISS
B. The ISS has a larger velocity than the spacecraft, so it will leave the spacecraft behind
C. The spacecraft will get to an higher altitude than the ISS
D. Nothing, they will stay at their initial distance

Answer: A. The spacecraft will overtake the ISS
What is the effect of a posigrade burn on a circular orbit?

A. The altitude 180° from the burn point is decreased
B. The altitude 90° from the burn point is decreased
C. The altitude 180° from the burn point is increased
D. There is no effect

Answer: C. The altitude 180° from the burn point is increased
What is the reference point of the rendezvous profile diagram?

A. The control center
B. The chaser
C. The center of the Earth
D. The target

Answer: D. The target
What is the shape of a circular orbit, for the chaser, in a rendezvous profile diagram? (assuming the target is higher than the chaser).

A. A point
B. A cycloid
C. A periodic wavy and pointy curve
D. A line
E. A sinusoidal

Answer: D. A line
A spacecraft on a circular orbit at 400 km does a retrograde burn of 1 m/s. What will be the change in the altitude (in km) of the perigee?

A. 1.5
B. 2.5
C. 4.5
D. 3.5

Answer: D. 3.5
A chaser is on a circular orbit at the same altitude as the target and few kilometers behind. Where will the chaser be one orbit after a posigrade burn ?

A. The chaser will be much further ahead
B. The chaser will be behind the target, further away than it was initally
C. The chaser will be higher than the target
D. The chaser will be lower than the target

Answer: B. The chaser will be behind the target, further away than it was initally
What is the definition of the Astronomical Unit (AU)?

A. It is the average distance betwteen the Moon and the Earth
B. It is the average radius of the Sun
C. It is the average radius of the solar system
D. It is the average distance between the Earth and the Sun

Answer: D. It is the average distance between the Earth and the Sun
What is the sphere of influence?

A. A sphere around each planet inside which the motion of a spacecraft is considered to be two-body Keplerian
B. A region in space that can be controlled by a spacecraft
C. A sphere around each planet inside which the motion of a spacecraft must be considered a three-body Keplerian problem
D. The region around the Sun in which only planets have a gravitational influence

Answer: A. A sphere around each planet inside which the motion of a spacecraft is considered to be two-body Keplerian
What is the hyperbolic excess velocity?

A. The velocity needed to reach the sphere of influence
B. The velocity at which we cross the sphere of influence
C. The velocity needed to reach the arriving planet
D. The velocity required to get into a LEO orbit from the surface of the Earth

Answer: B. The velocity at which we cross the sphere of influence
A interplanetary probe is in the sphere of influence of the Earth, in transit towards an inner planet. What is its energy with respect to the Earth?

A. E <= 0
B. E < 0
C. E > 0
D. E = 0

Answer: C. E > 0
What is the ideal shape of the transfer trajectory between two planets, and why?

A. A straight line, because is it the shortest path
B. A Hohmann transfer orbit, because it is the less expensive orbit in terms of energy
C. A straight line, because it is the less expensive orbit in terms of energy
D. A Hohmann transfer orbit, because it is the shortest path

Answer: B. A Hohmann transfer orbit, because it is the less expensive orbit in terms of energy
An interplanetary probe is in transit towards an inner planet, very close to the arrival planet. How is the velocity of the planet with respect to the velocity of the probe?

A. faster
B. identifical
C. slower

Answer: C. slower
There is no burn during the slingshot maneuvers and yet the speed in the heliocentric reference frame increases. How is that possible?

A. At the periapsis of the slingshot, some massive object is jettisoned
B. An ion thruster is systematically switched on and this type of propulsion is only efficient in planetary neighborhood
C. The velocity vector of the probe is not changed in norm, but in direction in the planetocentric reference frame

Answer: C. The velocity vector of the probe is not changed in norm, but in direction in the planetocentric reference frame
What can Gravity-assist be used for? (more than one answer possible)

A. Make communications between the probe and Earth easier
B. Decrease the heliocentric velocity
C. Explorations of "worlds" during the transit flight to the destination
D. Increase the heliocentric velocity

Answer: B. Decrease the heliocentric velocity
C. Explorations of "worlds" during the transit flight to the destination
D. Increase the heliocentric velocity
In space propulsion, what is true about the specific Impulse (Isp)?

A. It is expressed in seconds
B. it is an expression of the propulsion system efficiency
C. It is related to the exhaust velocity
D. it changes with the gravity value g
E. It expresses the impact of the local gravity on the launcher capability to reach orbit.

Answer: A. It is expressed in seconds
B. it is an expression of the propulsion system efficiency
C. It is related to the exhaust velocity
There are various combinations of fuel and oxidizer which exist. Which combination gives the biggest Isp among the following?

A. Kerosene/N2O4
B. N2H4/N2O4
C. N2H4/LOX
D. MMH/N2O4
E. LOX/LH2

Answer: E. LOX/LH2