question,propositions,labels,justification,answerable,uid
True or False? An object that is not accelerating or decelerating has no forces acting on it.,"['True', 'False', 'Impossible to say without more information']","[0, 1, 0]",,True,ff0e8305-73e0-404a-a775-4e7be538d99b
"Complete the following: During its orbital period, as a planet moves farther away from the sun, the orbital velocity of the planet ...","['remains the same', 'increases', 'decreases']","[0, 0, 1]",,True,40a73e51-5eb4-46d3-baab-8acd624f2287
Which affirmation is true when talking about Earth’s potential energy?,"['The potential energy is positive', 'The potential energy is constant', 'The potential energy is negative', 'None of the above answers']","[0, 0, 1, 0]",,True,883f8ed7-8b2a-4671-80d3-f68791fa4118
Why do we talk about microgravity in LEO?,"['All the external forces are not cancelling exactly', 'In LEO orbits, the Earth’s gravity is not exactly zero', 'The free-fall trajectory gets perturbed', 'None of the above answers']","[0, 0, 1, 0]",,True,7667b6ef-31e5-4ff3-87e2-65f9a4467551
To what wavelength is the atmosphere the most transparent?,"['X-rays', 'Visible light', 'Infra Red', 'Radio Waves']","[0, 0, 0, 1]",,True,b855830d-0498-4c21-8aca-ac69c917178c
"In the atmosphere and space environment, what best describes the so-called airglow?","['Photo ionization of oxygen', 'Northern lights', 'Diffraction of the Sun light in the upper layers of the atmosphere', 'Photo Ionization of Hydrogen']","[1, 0, 0, 0]",,True,e8663499-3be2-4284-88b1-6bada5682f75
"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?","['thermosphere, troposphere, stratosphere, mesosphere', 'troposphere, mesosphere, thermosphere, stratosphere', 'troposphere, stratosphere, mesosphere, thermosphere', 'troposphere, mesosphere, stratosphere, thermosphere']","[0, 0, 1, 0]",,True,1b6dbef8-074c-47b0-aba9-5b291196850d
What are the Van Allen belts?,"['The region between 90 and 100 km altitude', 'Low radiation regions', 'Much used orbits for telecommunication', 'Radiation belts']","[0, 0, 0, 1]",,True,9d24c8a3-5a62-4b10-a5c6-82a9a7173042
"Why is the inner radiation belt harmful for satellites, and more so than the outer belt ?","['Inner radiation modify the magnetic field and will damage optical system of satellites.', 'Inner radiation traps space debris which damage the structure of satellites.', 'Inner radiation traps protons which are more likely to damage on-board electronics.', 'the question is not correct, the outer belt is more harmful for satellites.']","[0, 0, 1, 0]",,True,45402b06-b7b3-46b0-ae5c-1d3ad697d8b4
"The sunspot number is a value that changes with time, with a period of approximately...","['7 years', '9 years', '11 years', '13 years']","[0, 0, 1, 0]",,True,920728e6-584b-46bd-b596-80aaab4ccfad
"True or False: the latitude of sunpots during a solar cycle stays uniform and constant, regardless of the sun activity","['True', 'False']","[0, 1]",,True,32387be2-0b71-47c8-abbf-b06d60781657
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?,"['At solar maximum, you have higher atmosphere density, which means more drag, and reduced satellite lifetime', 'At solar maximum, you have lower atmosphere density, which means less drag, and and increased satellite lifetime', 'At solar minimum, you have higher atmosphere density, which means more radiation, and reduced satellite lifetime', 'At solar minimum, you have lower atmosphere density, when means less lift for the satellite, and reduced lifetime']","[1, 0, 0, 0]",,True,433d3c7b-4f56-4934-ac4b-d513d975c33b
"Based on your understanding of the solar cycle, where would be the best place to see auroras? (select all that apply)","['Close to Antarctic and Arctic circles', 'Near the equator', 'Iceland or northern Scandinavia', 'Latin America']","[1, 0, 1, 0]",,True,e8128a5b-c008-49cd-ba2e-e859042da89d
What would be the most appropriate time to observe auroras?,"['2018', '2023', 'anytime', '2029']","[0, 1, 0, 0]",,True,81c4c4ae-b178-4a9d-8f2d-1f9b1a2b4d52
What is the main driver of the shape of solar prominences ?,"['Van Allen radiation belts', 'Earth', 'Magnetic fields generated by the sun', 'The orbital forces of Mercury']","[0, 0, 1, 0]",,True,a5a8edfe-c124-4b53-99f4-bca48e0f12fc
What is the difference between CMEs (Coronal Mass Ejections) and prominences ?,"['CMEs do not reconnect towards the sun. They also emit in lower wave-lengths.', 'There is no difference', 'Prominences and CMEs appear at different times of the day', 'CMEs are only caused by radiation belt']","[1, 0, 0, 0]",,True,04ad623a-86b3-46ac-8762-ce379d9258cf
What is the typical lower boundary of the Van Allen belts?,"['Below the ISS altitude', 'Half-way to the Moon', '500-600 km, roughly the altitude of the Hubble Space Telescope', '200-300 km, roughly the altitude of the Hubble Space Telescope']","[0, 0, 1, 0]",,True,88326631-7955-4fcd-8bb7-1a2c73fd5dd0
What is the global shape of the Earth radiation belts?,"['Spherical', 'Rectangular', 'Toroidal', 'Triangular']","[0, 0, 1, 0]",,True,e7426a1d-3e9f-4a96-bf76-e39df49b5458
What is the sectional profile of the Earth radiation belts?,"['Banana-shaped, with the extremities away from the Earth', 'Banana-shaped, with the extremities close to the surface of the Earth', 'Rectangular', 'Disk']","[0, 1, 0, 0]",,True,6249156c-13d9-4ce4-9abf-46bf65e50b60
The activity of the Sun has a periodicity of 11 years. What are the methods to observe it? (Select all that apply),"['Count the number of sun spots', ""Measure the Sun's bolometric flux (i.e. the flux over the whole spectrum)"", ""Measure the Sun's flux in a spectral band called H-alpha"", ""Measure the Sun's flux at a wavelength of 10.7 cm""]","[1, 0, 0, 1]",,True,e61de4a5-23be-4d82-92d0-fea5117b41a1
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?,"['Up to the distance from the Sun to Mercury', 'Up to the distance from the Sun to Earth', ""A siginificant fraction of the Sun's radius"", 'Up to the size of the Earth']","[0, 0, 0, 1]",,True,2f361e84-1b61-42b8-85e7-382e098b3512
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?,"['The flux of light from the Sun is lowered.', 'The Sun darkens from the observer point of view', ""None, it's too far away"", 'A gust of charged particles']","[0, 0, 0, 1]",,True,04660f0a-19fc-4b41-82c2-9f4c2245bf07
What is the magnetosphere?,"['A spherical object composed solely of magnetic material', 'A region that surrounds an object that has a magnetic field, usually a dipole which is distored by charged particles', 'A region in Indonesia', 'A region that surrounds an object that has a magnetic field, which tunnels neutral particles away from the object']","[0, 1, 0, 0]",,True,a279f385-4896-4877-8c32-c265ae0f6b31
"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?","['It increases', 'It descreases', 'It stays the same', 'Impossible to say, we need more information to answer']","[1, 0, 0, 0]",,True,dea1ba45-fcb4-454c-ab94-8a06a4d4f2f4
Crossing the South Atlantic Anomaly (SAA) with a satellite can greatly restrict its performance. Why?,"['The SAA is a region of permanent shadow over the South Atlantic, thus there is no power generated by the solar panels.', 'The SAA is a region of extremely high radiation. Radiations create errors in the onboard electronics which can potentially be permanent.', 'The SAA is a region of extremely low radiation. This induces large currents in the onboard electronics which degrades the performance.', '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.']","[0, 1, 0, 0]",,True,8b9f71e4-c6db-45d7-8199-a83a58c31074
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?,"['Object X', 'Object Y', 'Both at the same time', 'Impossible to say']","[0, 0, 0, 1]",,True,274915a7-1ad4-49f5-979e-c38c3994eba4
"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","['23 years', '24 years', '25 years', '42 years']","[0, 0, 1, 0]",,True,20566fe9-5314-4bb3-a0b7-4e9f01f8c396
Hubble's solar arrays were damaged because of collisions with:,"['Orbital debris', 'Meteorites with a 10e-5 cm diameter', 'Meteorites with a 10e-2 cm diameter', 'Meteroites with a 10 cm diameter', 'The famous cosmos-irridium breakup that destroyed the primary mirror of the telescope']","[1, 1, 1, 0, 0]",,True,80824e85-50b6-4981-9056-5f91e3bd6326
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?,"['1.72 m/s^2', '8.68 m/s^2', '0 m/s^2', '7.78 m/s^2']","[0, 1, 0, 0]",,True,2772845a-52cb-4686-8cfe-b19647b0ad18
"What is the escape velocity from the surface of the moon Europa (mass M = 4.8e22 kg, radius 1560 km)? (answer in km/s)","['1.072', '2.026', '3.48', '6.01', '9.96']","[0, 1, 0, 0, 0]",,True,90c76998-7060-491c-a0fb-3ae580a72a22
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?,"['0.2', '1.4', '2.7', '3.6', '5.4']","[0, 0, 0, 0, 1]",,True,6df3d9f1-800e-4b7d-b9ca-ce2ef8090718
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 ?,"['You, by jumping the equivalent of 50 cm on Earth.', 'A tennis ball hit by Roger Federer.', 'A bullet shot by a pistol.', 'None of the above.']","[1, 1, 1, 0]",,True,dcd48a6f-2c96-42e6-b75e-b5cb28b2c1fa
"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?","['For sure, the lander is lost.', ""The lander's chances are fair, but there is a significant risk."", 'All is good, not to worry, Philae will come down for sure.']","[0, 1, 0]",,True,6570bf60-a707-4f9b-ad31-d7bf390a306f
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),"['4.7', '5.0', '5.3', '5.6', '5.9']","[1, 0, 0, 0, 0]",,True,cfaa1256-9ed3-460b-b6d4-2a79e2b335f2
"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.","['g0 * R * p^2', 'g0 * R * p', 'g0 * R', 'g0 * R^2']","[0, 0, 1, 0]",,True,bef97b27-a677-488c-9088-b835c0f3d1a8
"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)?","['V = mu * r', 'V = sqrt( 2 * mu / r^3 )', 'V = sqrt( mu / r )', 'V = sqrt( 2 * mu / r )', 'V = sqrt( mu / 2r )']","[0, 0, 0, 1, 0]",,True,57080b4d-b331-4816-985f-c76f499662f6
"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?","['The ISS is constantly rotating around its main axis, creating the illusion of weightlessness.', '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.', 'Thrusters are in constant use which generate a force such that there is weightlessness.', 'None of the above.']","[0, 1, 0, 0]",,True,808bd743-7703-452b-a0bb-05516948c7d4
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.,"['Etot >= 0', 'Etot < 0', 'Etot is close to + infinity', 'Etot is close to - infinity']","[1, 0, 0, 0]",,True,0d0d9c07-d33a-4624-9597-1222c4479572
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?,"['Decrease the energy of the probe.', 'Increase the velocity by 12 km/s.', 'Wait until the orbit is perturbed enough to flyby Mercury.', 'Increase the energy of the probe.']","[1, 0, 0, 0]",,True,169dbc4a-48cf-40f8-b67b-654da412029f
What is the orbital velocity of the Hubble Space Telescope which is on a circular orbit at 555 km altitude? (answer in km/s),"['4.00', '6.21', '7.58', '8.02']","[0, 0, 1, 0]",,True,5f013dd6-d16e-4e1f-91f2-84dd2711e47c
What is the strength of the Earth’s acceleration in LEO?,"['Same acceleration than on the surface of the Earth', 'No acceleration, that’s why you can float in space', '90% of the acceleration on the surface of the Earth', '10% of the acceleration on the surface of the Earth']","[0, 0, 1, 0]",,True,7b343016-967c-4a4c-a892-be3e07a6992b
Which of the following proportionnality relation with the orbital period T with respect to the semi-major axis a is correct?,"['T^2 is proportional to a', 'T^2 is proportional to a^2', 'T is proportional to a', 'T is proportional to a^(3/2)']","[0, 0, 0, 1]",,True,503e9f15-7799-4813-b0ad-b87c053b9cc3
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?,"['T = 2*pi * sqrt( a^3 / mu )', 'T = 2*pi * sqrt( a^2 / mu )', 'T = 2*pi * sqrt( a^(1/2) / mu )', 'T = 2*pi * a^3 / mu']","[1, 0, 0, 0]",,True,176ce268-f5ed-4c3e-bf98-b53c8c63fed0
"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 = R ( hp + ha ) / 2', 'a = R ( ha - hp ) / 2', 'a = 2R + (ha + hp) / 2', 'a = R - (hp + ha) / 2', 'a = R + (ha + hp) / 2']","[0, 0, 0, 0, 1]",,True,874c48df-381b-4887-a2b8-fa09963fbb2f
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?,"['18.0', '89.5', '95.0', '100.9']","[0, 0, 1, 0]",,True,6ef8b7da-7aea-4809-95ce-c17f64866bee
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?,"['0', '1', '1.3', '0.5']","[1, 0, 0, 0]",,True,5064e3a3-16e9-431c-816e-3d8cd10c9331
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?,"['7.01°', '0°', '3.2°', '45°']","[0, 1, 0, 0]",,True,6192c62d-489d-45e4-acf6-23083a809273
"In orbital mechanics, what is the meaning of the mean motion n = sqrt( mu / a^3 )?","['It is the average angular rate over one full orbit, in rad/s', 'It can be defined only for parabolic orbits.', 'It corresponds to the instantaneous angular rate for a non-circular orbit.', 'In the specific case where the eccentricity e tends to zero, the mean motion and the true anomaly tend to be equal.', 'The mean motion relates to the true position of a body moving along a Keplerian orbit.']","[1, 0, 0, 0, 0]",,True,bc2f3517-6e5a-4b39-89c6-fb11c2209392
What reference frame is the best suited for an interplanetary probe?,"['Geographic coordinate system', 'Geo-centric coordinate system', 'Heliocentric-inertial coordinate system']","[0, 0, 1]","The center of the heliocentric-inertial coordinate system is the Sun. The two other coordinate systems use the Earth as center, and are not appropriate to for an interplanetary probe.",True,8d7cc580-c7b9-4875-9ba6-bf468df0a61d
The complete precessional cycle of the Earth lasts about 26000 years. What is the precession rate? (in degrees per year),"['0.00384', '0.01384', '0.02384', '0.03384', '0.04384', '0.05384']","[0, 1, 0, 0, 0, 0]",The precession rate per year is 360°/26000 years = 0.0138°/years.,True,e4fda0e7-b147-48fd-bcea-fbc007d2ee9b
What is the RAAN?,"['The inclination of the orbital plane.', 'The time of the periapsis transit.', 'The angle from a reference direction to the point where the satellite crosses the plane of reference, towards the south.', 'The angle from a reference direction to the point where the satellite crosses the plane of reference, towards the north.']","[0, 0, 0, 1]","The longitude of the ascending node (Ω) is one of the orbital elements used to specify the orbit of an object in space. It is the angle from a reference direction, called the origin of longitude, to the direction of the ascending node, measured in a reference plane.",True,7c7013ed-cb14-4298-a435-259072390c40
How long is a sideral day?,"['24h00min', '24h04min', '11h56min', '23h56min']","[0, 0, 0, 1]","The sidereal day, is the time it takes for the Earth to make one full rotation with respect to the stars, 23h56'04''.",True,e5939e55-2802-4753-b849-2efdd4aafa9a
Where is an orbital maneuver Delta-V adding energy to a spacecraft on orbit best performed?,"['Along the orbital velocity', 'Radially', 'Along the orbit angular momentum', 'Any direction of the Delta-V vector will add energy to the spacectaft on orbit.']","[1, 0, 0, 0]","In the impulsive case, only maneuvers along the velocity will impact the energy. Radial and cross-track maneuvers will only change the direction of the speed without changing its norm.",True,3e8adab1-90a8-4d92-a636-f514f12d90cf
What is the Hohmann transfer for small Delta-V useful for?,"['Interplanetary trajectories', 'Earth-Moon transfer', 'Manoeuvers around small bodies (e.g. comets)', 'Orbital rendez-vous']","[0, 0, 0, 1]",,True,b706586d-50b8-4d17-b9f2-890c679ff6e8
Where is the Delta-V for an inclination change smaller?,"['at low altitudes', 'at high altitudes', 'at the equator', 'at the poles']","[0, 1, 0, 0]","The Delta-V for inclination change is proportional to the orbital velocity. Thus, the smaller the orbital velocity is, the less is required to change the inclination and RAAN. The orbital velocity decreases with the square of the distance from the center of the body, thus higher altitudes are better.",True,a972601f-0015-48b8-8747-5e5dd8e92e12
What is the difference between geostationary and geosynchronous orbits?,"['Geostationary has an orbital period of 24h whereas geosynchronous orbits is 23h56', 'The orbital parameters for geostationary are inclination = 0° and eccentricity = 0', ""A geosynchronous satellite orbits the same location over Earth's surface while a geostationary satellite remains on average at the equator"", 'All of the above']","[0, 1, 0, 0]","A geostationary satellite orbits the same location over Earth's surface while a geosynchronous satellite remains on average at the equator. The definition of geostationary orbits is orbital period is Earth's sideral day, e = 0 and i = 0°",True,e723f537-9123-4794-99c4-6dc0f39f9e8f
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?,"['12.5', '15', '17.5', '20', '22.5']","[0, 0, 0, 0, 1]","At LEO altitudes, the typical orbital period is 90 min. In an hour the Earth rotates by 15° (= 360° / 24h), thus in 90 min, we have a shift of 22.5°",True,60f3877b-24ba-45fe-af9e-d67d14170174
"For a circular orbit of a given inclination, at what altitude will a satellite be impacted the most by nodal regression?","['200 km', '2000 km', '500 km', '12000 km']","[0, 0, 0, 0]","The lower the satellite, the stronger the effects of the nodal regression.",True,f9c603e5-f517-4636-849f-350a2759fcdc
"Among the following assertion about Lagrange points, which one is true?","['The Sun-Earth system does not have any Lagrange points because of the Moon', 'The distance between the Lagrange points and the Earth varies drastically with the seasons', ""The Lagrange points orbit the Sun with the same orbital period as the Earth's"", 'None of the above']","[0, 0, 1, 0]",The Lagrange points orbit the Sun with the same orbital period as the Earth's. The mass of the satellite on a Lagrange point is adjusted (lessened in the case of L1 and highthened for L2) such that the orbital period remains one year.,True,41c719d0-9f62-40da-abeb-8bd99a86ef8b
"A spacecraft is below and behind the ISS, both are on circular orbits. What will happen to their relative position?","['The spacecraft will overtake the ISS', 'The ISS has a larger velocity than the spacecraft, so it will leave the spacecraft behind', 'Nothing, they will stay at their initial distance', 'The spacecraft will get to an higher altitude than the ISS']","[1, 0, 0, 0]",The orbital velocity decreases with altitude (with the square root of the inverse to the distance to Earth's center). Thus the spacecraft moves faster and will catch-up with the ISS and eventually overtake it.,True,a2db30ce-3528-4548-a228-c27b103a545c
What is the effect of a posigrade burn on a circular orbit?,"['There is no effect', 'The altitude 90° from the burn point is decreased', 'The altitude 180° from the burn point is decreased', 'The altitude 180° from the burn point is increased']","[0, 0, 0, 1]","At the burn point, the velocity is increased. It means that the energy of the spacecraft changes and the geometry of the orbit changes. The altitude of the burn point will not change, but becomes the minimal altitude if the initial orbit is circular. Its maximum will be reached at the apogee, 180° from the perigee. Thus the altitude 180° from the burn point is increased.",True,11665c59-aacf-437d-b83e-16aaa6921ced
What is the reference point of the rendezvous profile diagram?,"['The chaser', 'The target', 'The center of the Earth', 'The control center']","[0, 1, 0, 0]",The rendezvous profile diagram is centered and relative to the target.,True,a28c168f-3f6a-4edb-b0c0-2ae974963858
"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 point', 'A periodic wavy and pointy curve', 'A line', 'A sinusoidal', 'A cycloid']","[0, 0, 1, 0, 0]","On a circular orbit, the altitude does not change, so the value of the R axis does not change. The V axis does not stay the same as the velocity of the two spacecraft are not the same. The chaser will move along an horizontal line in the diagram.",True,e8b2cae4-92f6-48e6-9436-c5f33a5ac832
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?,"['1.5', '2.5', '3.5', '4.5']","[0, 0, 1, 0]",This can be computed in a straightforward way using the equation Delta-r is close to 3.5 * Delta-V where Delta-r is in km and the burn value in m/s.,True,61e3c07e-fd5e-4429-aeb1-66afe0919eda
"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 ?","['The chaser will be much further ahead', 'The chaser will be behind the target, further away than it was initally', 'The chaser will be higher than the target', 'The chaser will be lower than the target']","[0, 1, 0, 0]","Since there is a posigrade burn, the altitude of the semi-major axis is increased, the orbital velocity is decreased. If the change of altitude is sufficient, the chaser will drift behind the target further away than it was initially.",True,9fc96902-8398-4630-b53b-6d3049c8254e
What is the definition of the Astronomical Unit (AU)?,"['It is the average distance between the Earth and the Sun', 'It is the average radius of the solar system', 'It is the average radius of the Sun', 'It is the average distance betwteen the Moon and the Earth']","[1, 0, 0, 0]","An Astronomical Unit is the mean distance between the Earth and the Sun. In 2012, the International Astronomical Union defined the distance to be 149,597,870,700 meters.",True,3fedeb91-5ab5-45de-be70-a2ce8ad59e10
What is the sphere of influence?,"['A region in space that can be controlled by a spacecraft', 'The region around the Sun in which only planets have a gravitational influence', 'A sphere around each planet inside which the motion of a spacecraft must be considered a three-body Keplerian problem', 'A sphere around each planet inside which the motion of a spacecraft is considered to be two-body Keplerian']","[0, 0, 0, 1]","For the Earth, the radius of the sphere of influence is about 924 000 km.",True,6a0ff5bb-46cb-4b10-a12b-4573589bb59f
What is the hyperbolic excess velocity?,"['The velocity required to get into a LEO orbit from the surface of the Earth', 'The velocity at which we cross the sphere of influence', 'The velocity needed to reach the arriving planet', 'The velocity needed to reach the sphere of influence']","[0, 1, 0, 0]",It is the speed in excess of the minimum velocity required to reach the sphere of influence.,True,f274dd2f-9811-4424-abca-f3c6e4c61bd8
"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?","['E <= 0', 'E < 0', 'E = 0', 'E > 0']","[0, 0, 0, 1]","The energy for the hyperbola is epsilon = + mu / 2a (energy per unit mass), thus positive. Another way to see this, is that the probe is no longer gravitationally bounded to the Earth, ergo its energy is positive.",True,42d75d3d-7aed-4cc3-a784-814bfc3e0fd6
"What is the ideal shape of the transfer trajectory between two planets, and why?","['A Hohmann transfer orbit, because it is the less expensive orbit in terms of energy', 'A straight line, because is it the shortest path', 'A Hohmann transfer orbit, because it is the shortest path', 'A straight line, because it is the less expensive orbit in terms of energy']","[1, 0, 0, 0]","The Hohmann transfer is the optimal and ideal trajectory in terms of time of flight and fuel. However, in reality, different trajectories are preferred. For Mars transfer, more energetic trajectories are usually preferred to shorten the time of flight.",True,b2345b77-cb06-476f-82f4-092f001b8356
"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?","['faster', 'identifical', 'slower']","[0, 0, 1]","The transfer ellipse ressemble a Hohmann transfer to go from a high to a lower orbit, thus the velocity of the probe is higher than the arrival planet. When leaving the Earth, the probe should also reduce its heliocentric speed. This can be done by crossing the sphere of influence with the velocity vector of the spacecraft in the opposite direction of Earth's velocity vector.",True,e344b8fb-a2cc-42b2-979c-544644a2a5b0
There is no burn during the slingshot maneuvers and yet the speed in the heliocentric reference frame increases. How is that possible?,"['At the periapsis of the slingshot, some massive object is jettisoned', 'An ion thruster is systematically switched on and this type of propulsion is only efficient in planetary neighborhood', 'The velocity vector of the probe is not changed in norm, but in direction in the planetocentric reference frame']","[0, 0, 1]","The norm of the velocity vector stays constant, there is no acceleration in the direction of the velocity vector. However, the direction of the trajectory of the spacecraft in the sphere of influence of the planet is a hyperbola. The direction of the velocity vector changes when the spacecraft is inside the sphere of influence.",True,6012cf0f-5cb3-440a-a35b-91c61539f393
What can Gravity-assist be used for? (more than one answer possible),"['Increase the heliocentric velocity', 'Decrease the heliocentric velocity', 'Make communications between the probe and Earth easier', 'Explorations of ""worlds"" during the transit flight to the destination']","[1, 1, 0, 1]","The most common application of gravity assist is to increase the heliocentric velocity. However, it can be reduced if the direction of the spacecraft velocity vector is well chosen when entering the sphere of influence. Voyager and Pioneer probes took advantage of their multiple gravity assist maneuvers to explore and take close-up images of all the planets in our solar system. This was made possible due to a particularly favorable alignement of the planets.",True,bb3def0d-b962-4777-84f9-bdd55055516a