Astronomy enables?
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Discovery
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Astronomy Invention Timeline and Limits
Stellar Parallax -> Telescope -> Spectroscopy + Photography (natural limit due to atmosphere absorption) -> space-based Telesopes
Beginning of Universe Timeline
Big Bang
Plank Time: everything was the same, only a fraction of a second after the big bang
Nucleosynthesis: Temperature and density dropped -> first particles formed like protons and electrons
Recombination: first aoms form He and H
Photon Decoupling: (until here Dark ages = no photons escaped before)
First Stars
Today
How does a star form?
Gravity causes mass to fall inwards while radiation pressure pushes mass out. If gravity wins -> collapse, if pressure wins -> oscillation due to increase of T -> pressure rises and so on.
Timeline of Star and Planet formation
Why do Bipolar jets form?
Mass acceleartes to the center and heats up extremly. Due to the angular moment it shoots out along the angular momentum axis. The energy comes from the roation
Why do gas clouds start to rotate?
Because mass is pulled inwards but does not meet perfectly at the center -> falls out after the CG and start turning -> rotation is started. thsi causes that the other mas is also pulled to the roation plane and a Protoplanetary Disk forms.
Whats the Roche Limit?
The closest distance a mass can be near another mass before disintegration. This depends on the density of both masses.
That wny rings form due to differetn s densities the have differetn disintegration radii
Criteria/Steps for evolution of a sun/star ?
Initially clouds of cold gas mostly of hydrogen:
Gravity pulls mass together
Rotation sprads mass out
Radiation Pressure pushes mass out
Nucelar fission starts if enough dense/hot
4 possible endings of a star?
Life Cycle of or Sun.
Formation
Protostar Phase
Main Sequence Star
Red Giant
Helium Burning
Planetary Nebula
White Dwarf Phase
Herzsprung-Russell Diagramm
What are failed Stars and how do they form?
Brown dwarfs are failed stars. They never reach the critical mass to start fusion. But they are belived to be massive enough to fuse heavy hydrogen, deuterium.
How can the age of a sund be determined?
Solar seismology: oscillations on sun’s surface
Radiometric dating of meteorites: measure isotropic ratios in meterites and comapre
galactic evolution: studying the formation of suns in other systems and comnpare to sun to estiamate age.
Structure of sun and key processes.
from inner to outer:
Core:
nucelar reaciotn of hydrogen to helium PP-chain
Radiative Zone:
varies a lot in density from ~gold to less dense then water
Energy trasnfer from core to above
Convection Zone
2/3 of Sun’s volume
much less dense than radiation zone ~dense as air a 50 miles altitude
hot material rises and then sinks -> convection circles which are also vicible on the surface
Photosphere
First layer of atmosphere
emits most of the sunlight
Chromosphere
Origin of prominences
Transition Zone
Corona
composed of plasma
From where are heavier elemetns then Fe beacuse suns cant produce them?
From neutron stars exploding
what causes the magnetic field in the sun and for what is it important?
By the convective motion of plasma in its outer layers. Important for solar activity, space wheater and the suns impact on the earth.
What are dark spots on the solar surface?
concentarted magnetic fields
Explain the solar cycle
22 years long with after 11 years flip of magnetic field. Maunder minimum (almost no dark sports) was observed which is not understood.
Composition of solar wind
charged particles primarily electrons and protons
whats a solar prominence and what types?
a solar filament. Very dynamic but cool structure consitss of plasma held by magnetic forces.
Types:
Quiescent Prominences
Eruptive Prominences
whats the heliopause and the termination shock?
Heliopause is the outer boundary of the heliosphere which is the suns influence in the interstellar room. Where the solar wind merges with the intertsellar medium is the termination shock
What are research problems for the sun?
how dies the sun generate the periodically reversing magnetic field
What causes the maunder minimum and how does the cycle recover from such minimas
why is the suns corona much hotter
What is the interplay between the sun and the interstellar medium
What are the inner planets?
Mercury, Venus, Earth and Mars. Are composed primarily from silicate rocks or metals
Describe terestrial planets:
low mass
small radii
large densities
rock forming elements and metals
interior striongly differentiates and msotly composed by core mantle and crust
Whats spcial abput mercury and what causes the sun phenomena?
least explored from inner planets
high gravity pull from sun makes it difficult
it is lokked in a 3/2 spin orbit resonace measn 3 times around own axis for every 2 orbits -> sun appears rising -> sinking then again rising. Due to eccentricity we have this 3/2 and not a calssical tidal locking like the moon.
some open science questions about mercury?
why is mercury’s normalised density higher then other terrestial planets
is the core liwuid or solid
is mercury geological active
Venus specs
92 bar surface pressure
460 °C surface Temperature
How was venus a long time ago?
may have had schdow liwuid watert oceans
venus and earth started out similar
Sun temp rose -> Oceans evaporated greenhouse effect casued thermal runaway
Why has venus no moons?
Due to suns gravity
Venus open questions
every life on venus
how has the surface and interior evolved
What evidence proves for water currently on mars and wat evidence proves for a wet ancient mars?
Currently:
detection of water in spils
water frost on surface
water-ice clouds
water at poles
Ancient wet Mars:
geomorphoogica features such as gullies rivers channels and streams
geological features such as sedimentary rocks
mineralogical features such as caly, sulfates..
where did the water on mars go?
The solar wind ripped of the atmosphere making it less dense so water evaporated and so on.
missing atmosphere -> missing insulation -> loss of water due to sublimation
what caused the atmosphere to be lost?
Loss of magnetic field at some point. No dynamo on mars.
The dynamo shut down either due to too rapid cooling (less likely) ot due to not enough heat transfer to the outsde -> no convection
what is a dwarf planet and example
a celestial body that:
orbits the sun
has enough mass to assume a nearly round shape
has not cleared the neighbourhood around it’s orbit
is not a moon
Example: Ceres
why did ceres never develope to a planet?
Gravitational pertubations of Jupiter prevented it.
What are the outer planets?
the Gas giants:
Jupiter
Saturn
Ice Giants:
Uranus
Neptune
What is metallic hydrogen?
Mixture of freee protons and electrons instead of discrete H2 molecules
Electrons can move freely -> metallic properties
Happens around 400 GPa
Jupiter specs:
Most massive planet
influences asteroid belt
First planet
took most of the mass left over frmom sun formation
Formation followed two steps:
ice and rock planetesimal formed
wiht high enough gravity gases were pulles from protoplanetary disk
Failed star
What drives the wheater on Saturn?
Helium percipitates from solution with hydrogen and froms dense raiindrops
When the drops fall through the metalic hydrogen, the drops converrt potential energy into kinetic energy which results into friction heat
Saturn specs:
Made of mostly hydrogen and Helium
Dense core at center made of FE and Ni surrounded by rocky material
Core is eveloped from liquid metallic hydrogen inside a lyer of liquid hydrogen which is similar to jupiter but much smaller
Lighting in the atmosphere converty methane gas into coke
Pressure in saturn center is so high that even diamonds wouldnt survive
Open Science Questions for Jupiter:
Generation and maintaince of vortices
Plasma transport mechanism and interaction with moons
Jupiters Atmosphere
three distinct cloud layers
Color of clouds comes from plumes of sulfur and phosphor contaiing gases rising from the warmer interior
Jupiters Magnetosphere
Largest and most powerful in solar system
by volume largest continious structure
Intenally driven
shaped by Io’s plasma and it’s own rotation (earth is shaped by solar wind)
Electromagnetic interaction with moons creates the ionized plasmas on the poles
Whats the great red spot on Jupiter?
Centruries old storm, 300km deep
Where is Jupiters core? Which one is plausible and what is known today?
Theory 1:
A dense core of heavy elements like, rock and metal grew by collecting debris. Once big enough gases were accumulated and the Jupiter toady known was formed
Theory 2:
Jupiter was formed from the large gas cloud that surrounded the sun. The gas cloud cooled and condensed forming instabilities. One of the more dense region pulled mor gas and collapsed to form Jupiter.
Theory 2 was ruled out when Juno measured a diluted core. A collision may have left Jupiter with the diluted core.
What are the explanations and observations that confirm the grand tack?
While Jupiter was movng closer to the sun , taking 99% of the left over mass, dor Ceres no mass was left so it became a dwarf planet.
Mars remained small becasue jupier cleared the mars region
Jupiter would have taken earth, mercury ans venus on the way towards the sun but due to the 2/3 resonance jupiter ans Saturn moved back out.
When Jupiter and Saturn moved back out thex kicked icy material from the asteroid belt inwards delivering water tzo the inner planets
Jupiter could have caused the extinction of dinosaurs whle kicking asteroids
Big object coming frm the interstellar room were captured by jupiters gravity and saving therfore the inner planets
Jupiters moon Io experiences tidal heating and thereby volcanism
Explain the grand Tack Hypothesis and why is it likely to be happened
Jupiter similar planets normally are closer to the sun and therfore also hotter. Such planaets have been observed in other stellar systems
Jupiter formed near the snow line of the early solar system around 3.5 AU
It then migrated inwards to 1.5 AU and got into a 2/3 resonance with Saturn
instabilities casued both planets to “tack” and move outwards
Saturn Magnetosphere
Similar to Jupiters ut weaker
energetic charged particles collide with netral atoms in titans upper atmosphere and energise them, causing it’s errosion.
How many Rings has Saturn and how do they look like?
seven main rings.
They are a collection of particles woth an avergae thickness of 10m with some vetical structures high up to 2.5 km
Moons plow thorugh the rings removing material and creating waves
Propeller like strucutres are created by the gravitational influence of moonlet
What are the spokes in SAturns rings?
Probably ring material that is temporarily charged and levitatetes by intteraction between magnetic field and solar wind.
The appera around automnal or vernal equinox
How did the ring form?
A moon that was too close was pulled apart and the ring was closed in a few days
Wher did urauns form?
Formed probably closer to the sun and moved outwards
From what does the atmosphere of Uranus consists of?
Mostly hydrogen and helium with a small amount of methane,water and ammonia. Methane clouds have strng absorption bands in the IR add red portion in the visible spectrum.
Rings of Uranus?
Consist mostly of bodies 20cm to 20m in diameter. They are confined by shepherding moons (interact gravitationaly to exchange angular momentum)
Wha is the spin axis of uranus tilted by 97.77 ° ?
Multiple Impacts
How long does a day and orbit last for uranus? what causes the big storms?
A day 17h but a season 21 Years so a full orbit lasts 21*4 = 84 years. The storm a caused bacause the sun shined for a wuarte of a year on one pole so causing high thermal gradients.
How was Neptune discoveredß
By mathematical calculations
Wha is Neptune bluer then Urauns?
Enhanced Picture was used wihtout saying that it was color graded. Color is the same as Uranus.
Whats special about the rings of Neptune?
In the outermost rings material clumps into three arcs.
Whats special about the magnetic fields of uranus and Neptune?
The are not alligned with the rotaional axis while others of Jupiter, Saturn and Earth are.
They are not located at the center of the planet
What casues the magentic fiedl in Uranus and Neptune?
Theory: superionic ammonia and ice, formed at very high pressures and temperatures. The fast spin rate produces weird looking magnetosphere
Whats special about Triton?
Neptunes moon Triton makes up 99.5 % of all mass orbiting Neptune.
Only large moon in pur solar system to orbit the opposite direction of it’s planets rotation.
Might have been captured in the Kuiper Belt
What is a moon?
A moon is a natural setellite that orbits a planet, dwarf planet or even an asteroid in pur solar system. Moons are typically smaller than the object they are orbiting and are held in place by the pull of their parent body.
Whats the theory of earths moon?
Collison theory where a mars sized object collided with proto earth and ejected silicate material which formed the moon. The magnetic core stayed in the earth.
How are the Mars Moons caled?
Phobos
Deimos
Mars Moons Origin?
Hypithesis 1:
Captured main-belt asteroid
-> moons have much i common but the orbits are too circular
Hypothesis 2
Mars collision wih planetesimal
-> porosities are inconsistent with asteroidal origin and would explain better the orbital plane
Name Jupiters Moon - The Galilean Satellites
Io
Europa
Ganyemede
Callisto
Internal structure of Galilean Satellites?
Io, Europa and Ganymede have a Fe-rich core. A mantle nad a crust.
What was the target of JUICE?
Ganymede ans to see if potential to support life.
Laplace resonanz of the Galilean Satellites.
Due to tidal forces and elliptical orbits the three moons are in laplace resonanz
Name Saturns Moons and who is the biggest?
Mimas
Enceladus
Tethys
Dione
Rhea
Titan -> over 90% mass of orbiting Saturn
Iapetus
Name Uranus Moons
Miranda
Ariel
Unbriel
Titania
Oberon
Name Neptune Moons
Triton
Proteus
Pluto Moon
Charon
Classification of small solar system bodies
All objects that are not a planet, dwarf planet or moon/satellites that orbit the sun, aer small solar system bodies.
Difference betwen asteroids and comets
Comets ave a tail due to outgasing. Asteroids not. Meteroids are all asteroids smaller than 1m in diameter
Where do Asteroids/Comets come from
from ht einital solar system forming, from the planetesimals
Where are Asteroids/Comets ?
In teh Kupier belt or Oort belt. An near the earthare also some
How did Ateroids belts evolve?
Due to the grand tack
Comets come from the Oort cloud to the inner solar system
ow is dust (very small comets) forming?
Due to collisions it gets smaller and smaller
Thermal cracking when they get closer to the sun
Whats the history of Ryugu?
Hayabusa mission returned samples from the asteroid ryugu. It formed due to impacts and it cotains water. Beacuse water is there it must have formed in the outer region
What did Rosetta Mission find?
Comets are made from pristine material synthesized in the solat nebula or during the earlier stage of solar system formation.
Ammonium salts were found which is relevant for life
Whats DART?
Double asteroid redirection test. A planetary defense test to shot a incoming asteroid awy or redirect it. How much mass s needed to deflect a asteroid..
Where did earths water came from?
Probably from asteroids because comets have deuterium which is heavy
Spacecraft Subsystems
Attitude COntrol
Propulsion
Thermal Control
Structure
Telemetry and command
Electric Power
Requirements ans standard of spacecraft
Feasibility
Safety
Reliability
Low mass and volume
Human factors
Cost
Compatibility of alls S/C elements
What loads occur during a launch on a S/C and what are the consequences?
Random vibrations
High acceleratios
Shocks
Acoustic laods
-> High mechanical loads on all parts
-> Strong structures required
List some features/conditions of the space environment and their consequences
Vacuum
no oxygen so life support needed
pressure suit needed
high thernal gradient due to no convection
material is outgasing so contamination
Gravity
low gravity reduces the contact to ground so less traction
dust will not settle so fast which results in less vision
Illumination
higly determines how much power can be generated with solar panels
extreme temperature gradients
psychological effects for astronauts
Temperature
thermal stress
outgasing
increased power demand for heating/cooling
Radiation
for humasn long term effects
computer errors
material degredation so properties can change
Impacts
particle impacts will casue mechanical damage, rupture or electrical failure
not so fast ones will accumulate and form a dust layer
Dust
for humans not good if inhaled, maybe toxic
Allergic response
Abrasion and wear increases
reduces signal strength, electrical power generation
cloggs moving parts
Contamination
avoid it for humans but also avoid bringing stuff back to earth
new viruses or
Propulsion systems
cold gas
chemical
main propulsion, energy in chemical bonds
typical Isp 200 - 450 s
high mass flow and thrust
liquid
solid
electric
high isp up to 3000 s
low mass flow and thrust
Nuclear
Mechanical
Main constrains for Aerospace structures
must survie the launch
should be as light as possibl
should provde a stable focus for optical instruments under thermal expansion
What has to be considered for Mecahnsism
problems with frictions and environmental conditions
often single point of failure
whats ADCS and waht for is it needed?
Attitude Determination and Control System
Sensors/Antenna need to point in a a adirection
No rotation is wanted
What are distrubances in space that a S/C could experience?
Gravity Gradient
Aerodynamic drag
Magnetic Torques
Solar Radiation
Mass Expulsion
Internal Changes
What Sensors do you know?
Star Sensors (for long exposure)
Sun sensors
Earth sensors
inertial measurement units
magnetometer
GPS
Name Passive attitude controls
Spin stabilization
Magnetic alignment
gravity gradient
Name active attitude controls
Thrusters
Reaction wheels
magentic torquers
What power generation types exist
batteries
realtive low energy densitiy but good for storage
Lithium ion
thermal management is crucial
RTG (radioisotope thermoelectric generators)
for mission far away from sun
low efficiencies
conversion from heat of nuclear decay into electric energy (seebeck effect)
reliable
long lifetime
decrease of power over time
political problems
solar energy
dependetn on local illumination
degredation
What are critical components for temperature?
fuel
mechanisms
sensors
What surafce types can be used to heat cool from radition
white/mirror for cooling
black for heating
what can be used to heat the S/C?
electric resitors
radioisotrpic heat from decay
what can be used to cool the S/C?
cryocooler
Peltier elements
radiators to radiate heat away
What means MAIT and name some procedures for the last word
Manufacuring assembly integration and Test
Tests are:
shakeer
Tvac
EMC
Acoustic
How can we explore a space object? and why do we need orbital mechnics?
remote
In situ
to get to the objects
What are the kepelrs Laws?
“Every planet travels round the sun in an elliptical orbit, with the sun at one focus. The moon, in the same way, travels in an ellipse round the earth, though in this case he recognized that the ellipse was not perfect.”
“The velocity of a planet varies with its distance from the sun in such a way that a line joining the planet with the sun sweeps out equal areas in equal times.”
“The square of the time taken by any planet to make a complete orbit is proportional to the cube of its mean distance from the sun.”
What orbit tranfers do we have?
Intercepting orbits
One-impuls maneuvres
Non-intercepting transfers
Two impulse trandfer
Three imoulse transfers
Continuous thrust transfer orbit
What changes can a one impulse do?
whats the oberth effect?
to achieve a certain delta v, the necessary impulse scales monotonically witht the velocty, being minimal at the lowest orbital radius and highest orbit velocity
What two impuls transfers do we know and explain.
Lambert transfer
general
Hohmann transfer
lambert wiht the least effort
only working f coplanar, elliptical and same cental body
Explain the three impulse to infinity
When we go to infinity, we basicly need to effort to cahnge orbit. We can ust his and go very far away to minimize the delta v needed. This is with a three impule transfer. We do one impule to “infinity” then do the orbit change and do the 3. And last impulse to stay in the end orbit.
what is patched conics?
we simplify the planets to two objects and there SOI to calcualte the transfer
Explain planet fly by#s
With a fly by we can change the robit and thereofre gain delta v. from planetocentric view the velocity does not change but from heliocentric it does and can therefore have a substantial influence because the vector orientation changes.
Classification of science payloads:
the main differences between Lab vs S/C instruments?
• Size
• Mass
• Power
• Number of products (often n = 1)
• Quality assurance
• Qualification effort
• Redundancy, failure tolerance
• Operation and autonomy
• Performance (resolution, accuracy)
• Data handling (compression, telemetry)
Name differnte space isntruments and their abbreavtions.
GCMS - gas chromatography with mass spectrography
XRF – x ray fluorence
CLUPI – close up imager (macro cam)
ProSEED - Drill
What from a planet do we want to measure ?
Interiors
Surfaces
Atmosphere
Planetary interiors:
Name properties we want to measure and what instruments we can use for it
Planetary surfaces:
Planetary atmosphere:
Name properties we want to measure and what instruments we can use for it for INTERPLANETARY MEDIUM
Whats the difference between Spectroscopy and Spectrometry?
Spectroscopy is when we look at it and observe how the matter interacts with electromagnetic radiation
Spectrometry is when we make sense out of the gathered data.
For what is Mass spectrometry good?
To measure the somposition of hte atmosphere. Charachterise the planetary material.
What subsystems consists the Mass Spectrometry?
Ionization source
Mass analyzer
Detector
What types of Mass spectrometry exist?
Sector Field (magnetic sector)
Quadrupole
Time-of-flight
Ion trap
Explain the Magentic Sector.
centrifugal force vs Lorentz
Ion sorce is kinetic energy
lighter ions will be deflected more
Keeping R and ionisation voltage const. -> specific Ions can be scanned
Explain the Quadrupole
They use a combination of DC and radio frequency voltages to permit selected ions with a specific m/z ratio to pass through the rod assembly.
Explain Ion traps
They use electric and magnetic fields to capture ions and selectively release them in a discontinous process.
Differetn configurations are possible:
Penning trap
Paul trap
Orbitrap
Explain time of flight
Iosn pass a field-free drift zone where they are seperated by their mass beacuse lighter ions travel faster. Because all ions have the same charge state, only the mass determines the travel speed. All the ions are recorded by the detector which results in a high sensitivity. TOF collect an entire spectrum where others scan across a mass range.
Explain the infrared spectroscopy
If the sun shines through a gas, different molecules will absorb different frequencies. This means that by measuring the frequency band, we can detect absorption features or absorption bands. The following frequencies absorb:
• 0.4 to 2.5 μm: crystal field electronic transition absorptions (electronic transitions of electrons)
• >1.4 μm: molecular absorption bands (fundamental molecular vibrational and rotational modes)
• 5 to 50 μm : fundamental vibration frequencies (structural, chemical, and physical properties)
• 7 to 11 μm: “transparency features”, e.g. quartz and feldspar (largely dominated by surface scattering)
many of rockforming elements between 5-50 um
What are typical wavelengths for Infrared spectroscopy?
UV, VIS-NIR, Mid-IR
Explain some features that occure for the infrared spectoscopry.
- The Christiansen Feature (CF) occurs near the Christiansen frequency where the real refractive index of the material is approximately equal to the refractive index of the medium. It depends mainly on the SiO2 content, as its position is indicative of silica polymerization.
- The Reststrahlen Band (RB) is caused by the stretching and bending of bonds between silicon, oxygen, and various cations and is therefore important in identifying feldspars, pyroxenes, and olivine.
- Transparency Features (TF) are caused by volume scattering and become more pronounced as particle size decreases.
what are soem challanges for infrared spectroscopy?
temperature
Grain size
Surface roughness
Directivity
Soil maturity
How can the mass spectrometer and a camera be calibrated?
Spectrometer:
Reference Gas
Complementary data, e.g. on solar wind direction
Camera:
Colour targets
Name some Instrument qualifications during development.
electromagnetic interference and compatibility
Vibration, Shock, Microvibraitons
Thermal Vacuum
What ESA mission classes exist?
How id the NASA flight mission project lifecycle categorised?
List some key points of Phase 0+A+B | C+D | E | F from the ECSS-M-ST-10C?
V-Model
Typical ESA mission phases:
1. Pre-Launch Phase (PLP)
2. Launch & Early Operation Phase (LEOP)
3. Transfer Phase (TP)
4. Commissioning Phase (CP)
- Performance Verification Phase (PVP)
- Science Demonstration Phase (SDP)
5. Nominal Operations Phase (NOP)
6. Extended Operations Phase (EOP)
7. Decommissioning Phase (DP)
8. Post-Operations Phase (POP)
9. Active-Archival Phase (AAP)
Typcal planetary surface mission phases:
1. Launch & Early Operation Phase (LEOP)
2. Interplanetary Transfer Phase
3. Orbit Transfer Phase
4. De-Orbitation, Descent and Landing Phase
5. Science Surface Operations Phase
How have space missions evolved over time?
The mission duratio is increased
more capabilities due to improved communication, processing and instruments
Commercialisation
Reusability
intrestingly the risks are still a issue and have not been diminished
How can Mission challanges be categorized and name some examples.
Mechanical issues
JUICE RIME antenna sue to stuck pin
Software glitches
Mars climate orbiter imperial units were used instead of metric (fail)
Deep Impact Spacecraft entered safe mode during eaerth flyby leading to temporary errors (recovered)
User errors
Huygens Lander only transmitted 350 out of 700 images because command to transmit over two cahnnels was not sent. So it was transmitted redundantly over both channels.
Environemt
Describe the landing on Mars and what can be used.
Mars Entry, Descent and Landing.
We can use:
Landers (small weight)
Sky crane for large rovers in 1t region
Ballons for small rovers in the 100kg range
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