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  1. Our view on climate change, the point where we are today and predictions are the result of scientific breakthroughs, steady developments and of course technological leaps. All of the above components are the keys for the climate models, upon which we fully rely. Firstly, I would like to share a link, which is different from popular climate change and modeling discussions with its analysis approach. https://medium.com/our-changing-climate/climate-modelling-from-manabe-and-wetherald-to-supercomputer-jasmin-1c8d5d11431b My second point would be human impact and actions planned and being done for the nearest future. Net zero 2050 might be unrealistic. But there should be a reasonable deadline, to sharpen international initiatives and economies. Even if a lot of plans exist only on paper or contradict the budgets, even environmentally unfriendly infrastructure cannot stop in that short period. My third point would be that climate changing is not only about emissions, models and personal carbon print. The whole technology and knowledge, which is in our hand should be used to follow the 2050 deadline, including space manufacturers, dedicated to global changes and local ecosystems monitoring as well as data sharing.
  2. Exactly, we are not searching a place for life arising. Even observation of it is dangerous as up to now every life ecosystem, that we have investigated, suffered from biologists intrusion (due to we have no other approaches). Search for life has to milestones: - is it there in any state? - is it 'on the same page' with us for communication?
  3. I haven't seen a clear statistics on the propellants used in sense of launches and hence the actual pollution from the rockets that we have today. There are a lot of factors, the most famous launches, tests and results are in the pioneering companies' reports all over the web. Solid rocket fuels can have a severe carbon footprint. But most of the rockets use either liquid or hybrid propellant engines: using solid at one stage and switching to the liquid on another. In some implementations solid propellant produces the best thrust in low thick the thickest atmosphere layers, at higher positions - liquid propellant is used. Liquid hydrogen fuel produces water exhaust. But it should be taken into account at the same time that hydrogen production causes significant carbon emission. Ozone depletion is also one of the rocket's exhaust impacts. ‘Solid fuel rockets have lower specific impulse, a measure of propellant efficiency, than liquid fuel rockets. As a result, the overall performance of solid upper stages is less than liquid stages even though the solid mass ratios are usually in the .91 to .93 range, as good as or better than most liquid propellant upper stages.’ - Wikipedia https://en.wikipedia.org/wiki/Rocket_propellant. A rocket's purpose (hence, the engineering design of mechanics and dynamics) dictate the factors of using a specific engine and propellants: travel distance, reusability, multi-start, net load, fuel. The typical limitation is combustion stability. Though the rocket launches are not so frequent to have a significant impact in the overall pie chart of the World’s carbon footprint, the space industry took it’s advantage on eco-fuel implementation. The rocket propellant new engines are being designed and tested non-stop. Example: ‘The Apollo Constellation Engine (ACE) is a Hall effect thruster propulsion system: Multi-propellant capability with Krypton, Xenon, and proprietary propellants.’ - September this year. Hybrid rocket: https://www.skyrora.com/skyhy This is a list of long read for a deep dive into the chemical part of the propellants: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/rocket-propellant
  4. It would be quite interesting to watch such proof/dueling happen. Did they survive to the forums era? "There are in fact two things, science and opinion; the former begets knowledge, the latter ignorance." Hippocrates, Law, 460-377 BCE
  5. There is no unique definition of life in astrobiology, metabolism is one of the most mentioned features. Still biocentrism manifests life in any diversity, so there are many possible definitions. Any feature of an exoplanet that doesn’t fit statistical data that we have could be a sign of life there. Unfortunately, we still do not have that much statistical data. Often the ‘misfits’ that are already found in the universe are forgotten (for instance, wandering planets). Today there is a lot of activity directed to the exoplanets investigation, habitable zone definitions, even volunteers are called to help AI to search for exoplanets. James Webb Telescope - the great mission is also targeted for exoplanets observation. Major defining criteria for a candidate of potential life holder are : - exomoons stable systems; - water containing planets; - exomoons near to gas giants; - any ‘Earth-like’ planet or exomoon might be a candidate for an alien life. 'To date, more than 4,000 exoplanets have been discovered and are considered "confirmed." However, there are thousands of other "candidate" exoplanet detections that require further observations in order to say for sure whether or not the exoplanet is real.' - NASA https://exoplanets.nasa.gov/faq/6/how-many-exoplanets-are-there/#:~:text=To date%2C more than 4%2C000,not the exoplanet is real
  6. Yes, the rockets do pollute. There is not one consolidated answer to that question in numbers due to the facts that there is no exact data of all the World'd launches and tests performed. As well as there is no exact dedicated measurements in the atmosphere. But there are some useful articles on that: https://www.space.com/rocket-launches-environmental-impact https://everydayastronaut.com/rocket-pollution/
  7. Totally right, thank you. - The numbers are duplicated and commented like that. And they really mean that there might be error, so there is no 100% result to be sure. - And this is totally different from anisotropic and is not making anisotropic conclusion in any word.
  8. The observable universe is isotropic and homogeneous. This was the main assumption at the start of calculations, observations and theories. The CMB map is the oldest detected radiation that was created after the big bang. The European Space Agency's Planck satellite produced the CMB map (that is also present in the Wikipedia article), showing measurements of the intensity and the orientation of the CMB all over the sky. https://www.esa.int/ESA_Multimedia/Images/2013/03/Planck_CMB ‘It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today.’ - quote That is what is meant by intensity. The calculated intensity odds are assumed to be caused by galaxy formation after the matter was cooled enough. Calculation of the odds of intensity show that the universe prefers one direction over another at 1 in 121,000. Planck Satellite, COBE and Hubble Ultra Deep Field combined show that the universe is isotropic. Every valuable article is a part of valuable knowledge on the subject. http://www.earlyuniverse.org/does-the-universe-look-the-same-in-all-directions/ https://phys.org/news/2016-09-scientists-universe.html Thank you for the comprehensive dialogue and every contribution.
  9. Gravastar is a way to go away from singularity. Relying on hypothesis on quantum gravity, which has not been quantized yet whether it will ever be done. A gravastar is filled with dark energy. That may link major subjects of investigation of the universe today. LIGO might differentiate a gravastar and 'normal' black hole during the merge. So, there is another alive hypothesis related to the subject.
  10. 'Flat curvature' here is 'zero curvature', where the local geometry is flat. 'Flat' is usually understood in 2D. But for the universe we are talking about local 3D flatness. There is still skepticism and no full agreement on what flatness should mean due to CMB measurement results, local gravitational lensing and curvatures. Flat universe ( lambda cold dark matter - ΛCDM) is an accepted model. If it is removed, the detected and observed phenomenon will not fit to CMB measurements and conclusions.
  11. Hi, What kind of rocket are looking to start with? Materials? Heights? Construction? The modeling gone quite far. 3D - printed liquid engine ones, cutting-edge within concepts are there. Couple words for guidance. I would be glad to give some advice.
  12. What is applied to the big bang, may be applied to a black hole n a speculative way. 'the main difference is that a black hole singularity is the end of space time (and pulls matter in) and the big bang singularity is the beginning of space time (where matter and space were made 'real')' The big bang - is an accepted starting point of the universe, an it is not the same of what black holes are. Prior to the big bang hypothesis are around in major, which hare not really the subject of GR. Thank you.
  13. I am not a judge of myself and the work done behind it. Consider it is 'flat'. Thank you for the points.
  14. Excuse me, if the information is repeated here. https://ocov2.jpl.nasa.gov/whats-new-oco-2/ 'The annual OCO-2 End of Year Review for 2021 concluded after reviewing all aspects of the project and the performance trends of the observatory and instrument. Overall, the hardware is performing well and we look forward to many more years of continued successful science operations and acquiring high quality data to support advances in carbon cycle science.' Officially, we don't know exactly what is CO2 situation, methane, the, burning in the debris higher atmosphere impact. What there is now - and an action done on all possible levels.
  15. Most of the heavy elements of the periodic table are lab - created. They are unstable before decaying into, for instance, plutonium or lead. LIGO might detect heavy elements for the neutron stars like isotopes in areas of stability. Detected gravitational waves confirm that merging neutron stars produce some of the heaviest elements but without a lot of data to have a sure confirmation.Till now extracting accurate quantities of the elements and spectrum data was not possible.
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