Score
Title
382
AskScience Panel of Scientists XVII
7363
I’ve read that when caterpillars are in their cocoons, they dissolve completely into goo; no original parts survive in the butterfly. How is the butterfly made from the goo? Is there an embryo that grows and uses the goo like a yolk sac? Or does the goo somehow arrange itself into new body parts?
104
How sustainable is our landfill trash disposal model in the US? What's the latest in trash tech?
16392
With all this fuss about net neutrality, exactly how much are we relying on America for our regular global use of the internet?
54
If tooth decay is just caused by the bacteria feeding and producing acid, would a person that just used listerine have the same dental health as a person that brushed without flossing?
16
Does boiling water in a low pressure atmosphere still kill pathogens?
16
My doctor says that chemotherapy works by specifically targeting rapidly-dividing cells, which is how it works to fight cancer and also why it has the side effects that it does. But how does it “know” which cells are rapidly dividing? And how rapidly is “rapidly”?
8
How mixable are different types of plastic? Like PET and HDPE?
15
How are isotopes used in nuclear physics Experiments isolated?
848
In 1996 NASA announced 'evidence of primitive life on early Mars'. In 2000, a second report supported the thesis. What happened next?
3
How are the needles for Atomic Force Microscopes made, and how can the tip be smaller than the atoms they are manipulating? What are their limitations?
8
How are the triple(or more) parachutes commonly seen on capsules returning from space kept apart?
3
What makes a laser shine in a straight line?
82819
Help us fight for net neutrality!
1
How do scientists determine the weight of huge (extinct) animals?
2
what's the difference between ZW and XY chromosomes, how did they evolve, and why are ZW organisms homogametic for males where XY organisms are heterogametic?
4
What's the current state of AIDS? Is it still basically a death sentence, or is it manageable? What are the consequences of getting AIDS nowadays?
1
What happened to the Global Cooling scare of the 1980's?
0
If a pipe was run from space straight into the ocean would water run up it and flow into space?
2
Can animals understand human body language like laughing or smiling?
2
Lithium batteries are being developed to power cars in response to the decline in fossil fuels, but will lithium eventually run out as well?
1
Question from my 4 year old sister, do other animals also get "Boogers"?
1
Is there any short-term geothermal or atmospheric effect that is caused by the sun heating one "side" of the earth at a time?
14
Could an electric vehicle stand a chance in a racing event?
23
If there is an ocean below the ice surface of Europa, is the ice shell buoyant? Geologically supported? Or is it kept in place by the distribution of gravity?
1
Is there a mathematical relationship between Moire patterns, Chladni plate vibration patterns, and the pattern formed by rings when making different cuts from wood?
2
Would readers of character based languages (e.g Chinese) experience dyslexia differently since they don't use strings of letters?
3
How to calculate eigenvalues in the Kirchhoff's thin plate model?
27
Do all individual atoms in a solid emanate their own blackbody radiation?
14
Is there anywhere other than Earth in the Solar system where you could see a total solar eclipse and/or total lunar eclipse equivalent?
4
How did we get solid matter from light? How did Photons and Electrons create solid matter in the early ages of the universe when everything was insanely hot?
3
Since the event at CERN that proved the existence of Higgs bosons/Higgs field, can we now see this event happen regularly now we know ‘where’ to look?
8
Why does turning on an electric blender in the kitchen cause my HD antenna signal to go out in a different room?
6
Can the human body survive breathing pure oxygen at lower pressures?
14
When beryllium-16 decays and produces 2 neutrons simultaneously, what happens to that dineutron?
6
How do we know the earth’s core is super hot and why is it so?
1
How does the pressure of the vacuum of space affect the ISS?
11184
From my kid: Can you put a marshmallow on a stick out into space and roast it with the sun?
3
Given that cerebrospinal fluid flows around the structures of the brain, would messenger chemicals from synaptic activity in one area be passed to, and alter synaptic activity in other regions of the brain?
9
How do we know what the tonsil does?
2
In a compound with an alkene and an alkyne, which would ozone cleave in an oxidative cleavage reaction?
39 CrustalTrudger > Could a meteor have struck Earth so hard as dislodge soil or rocks, shoot them into the atmosphere Yes, at least on the rocks parts (any unconsolidated material like soil would not survive the process). A good analogue are [Martian meteorites](https://en.wikipedia.org/wiki/Martian_meteorite). These are meteorites that fell on Earth, but were originally part of the Martian crust that were ejected from Mars during meteorite impacts on Mars. > and spread life into space? Little more uncertain. As discussed above, there is certainly the expectation of a decent amount of material from Earth that has been distributed throughout the solar system via impacts. For example, calculations considering the Chicxulub impact (the one thought to have brought about the K-T extinction) suggest that a [volume of Earth material equal to the size of the impactor was ejected into space](https://arxiv.org/abs/1204.1719). More general calculations [predict massive amounts of material were transferred between planets via ejecta, but mostly during the late heavy bombardment period between 3.8 and 4.0 billion years ago](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440031/). The real questions to which we don't know the answer are 1) how much of this ejecta was life bearing (i.e. we still have limited evidence of life on Earth from the before or during the late heavy bombardment, but some signs point to there being some microbial life at that time) and 2) under what circumstances (if any) would microbes ejected into space via this process remain viable? There are suggestions that depending on the size of the debris, [some viable DNA/RNA within microbes could survive for several million years](http://iopscience.iop.org/article/10.1088/0004-637X/690/1/210/pdf), but it's still uncertain whether that is actually quick enough for these ejecta to end up on a planet/moon where life could flourish (seems like a long time, but consider that many of the asteroids and meteors have been orbiting the sun without impacting large planets or moons since at least the end of the late heavy bombardment period 3.8 billion years ago).
8 LeonAnon The main problem with that is that the distance between stars is mindbogglingly large. The nearest next star is at 250000 AU, compared to 40 AU for Pluto. So by the time any microbes/life would have crossed the gap, their DNA (or equivalent) would have degraded beyond repair by hard cosmic radiation. Even on Earth, which is moderately shielded against radiation, DNA/RNA [completely degrades within 3-7M years](http://rspb.royalsocietypublishing.org/content/279/1748/4724), and gets fragmented beyond repair long before that. And then those fragments would still have to survive reentry on a new world.
6 64vintage I have read that since the origin of life on earth, there have been at least one and possibly multiple times when the surface of the earth was entirely uninhabitable - molten etc. Since the theory is that life evolved only once, the conclusion is that the earth was re-seeded by former ejecta that returned to earth many years later, when conditions were less hostile. On that basis, the answer to your question is yes. EDIT : https://nai.nasa.gov/annual-reports/2002/uw/giant-impacts-in-earths-early-history-reseeding-the-planet-and-the-search-for-earth-rocks-on-the-moon/ " Project Progress We explore the likelihood that early remains of Earth, Mars, and Venus have been preserved on the Moon in high enough concentrations to motivate a search mission. During the Late Heavy Bombardment, the inner planets experienced frequent large impacts. Material ejected by these impacts near the escape velocity would have had the potential to land and be preserved on the surface of the Moon. In order to determine whether the Moon has preserved enough ejecta to justify a search mission, we calculate the amount of Terran material incident on the Moon over its history by considering the distribution of ejecta launched from the Earth by large impacts. In addition, we make analogous estimates for Mars and Venus. We find, for a well mixed regolith, that the median surface abundance of Terran material is roughly 7 ppm, corresponding to a mass of approximately 20,000 kg of Terran material over a 10 × 10 square km area Mounting attention has focused on interplanetary transfer of microorganisms (panspermia), particularly in reference to exchange between Mars and Earth. In most cases, however, such exchange requires millions of years, over which time the transported microorganisms must remain viable. During a large impact on Earth, however, previous work (Armstrong et al., submitted) has shown that substantial amounts of material return to the planet of origin over a much shorter period of time (< 5000 years), considerably mitigating the challenges to the survival of a living organism. Conservatively evaluating experiments performed on Bacillus subtilis and Deinococcus radiodurans to constrain biological survival under impact conditions, we estimate that if the Earth were hit by a sterilizing impactor ~ 300 km in diameter, with a relative velocity of 30 km s-1 (such as may have occurred during the Late Heavy Bombardment), an initial cell population in the ejecta of order 10-4 – 10-2 cells kg-1 would in most cases be sufficient for a single organism to survive and return to an again-clement planet 3000-5000 years later. Although little can be said about the characteristics or distribution of ancient life, our calculations suggest that impact re-seeding is a possible means by which life, if present, could have survived the Late Heavy Bombardment."
37 0 CrustalTrudger > Could a meteor have struck Earth so hard as dislodge soil or rocks, shoot them into the atmosphere Yes, at least on the rocks parts (any unconsolidated material like soil would not survive the process). A good analogue are [Martian meteorites](https://en.wikipedia.org/wiki/Martian_meteorite). These are meteorites that fell on Earth, but were originally part of the Martian crust that were ejected from Mars during meteorite impacts on Mars. > and spread life into space? Little more uncertain. As discussed above, there is certainly the expectation of a decent amount of material from Earth that has been distributed throughout the solar system via impacts. For example, calculations considering the Chicxulub impact (the one thought to have brought about the K-T extinction) suggest that a [volume of Earth material equal to the size of the impactor was ejected into space](https://arxiv.org/abs/1204.1719). More general calculations [predict massive amounts of material were transferred between planets via ejecta, but mostly during the late heavy bombardment period between 3.8 and 4.0 billion years ago](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3440031/). The real questions to which we don't know the answer are 1) how much of this ejecta was life bearing (i.e. we still have limited evidence of life on Earth from the before or during the late heavy bombardment, but some signs point to there being some microbial life at that time) and 2) under what circumstances (if any) would microbes ejected into space via this process remain viable? There are suggestions that depending on the size of the debris, [some viable DNA/RNA within microbes could survive for several million years](http://iopscience.iop.org/article/10.1088/0004-637X/690/1/210/pdf), but it's still uncertain whether that is actually quick enough for these ejecta to end up on a planet/moon where life could flourish (seems like a long time, but consider that many of the asteroids and meteors have been orbiting the sun without impacting large planets or moons since at least the end of the late heavy bombardment period 3.8 billion years ago).
7 0 LeonAnon The main problem with that is that the distance between stars is mindbogglingly large. The nearest next star is at 250000 AU, compared to 40 AU for Pluto. So by the time any microbes/life would have crossed the gap, their DNA (or equivalent) would have degraded beyond repair by hard cosmic radiation. Even on Earth, which is moderately shielded against radiation, DNA/RNA [completely degrades within 3-7M years](http://rspb.royalsocietypublishing.org/content/279/1748/4724), and gets fragmented beyond repair long before that. And then those fragments would still have to survive reentry on a new world.
4 0 64vintage I have read that since the origin of life on earth, there have been at least one and possibly multiple times when the surface of the earth was entirely uninhabitable - molten etc. Since the theory is that life evolved only once, the conclusion is that the earth was re-seeded by former ejecta that returned to earth many years later, when conditions were less hostile. On that basis, the answer to your question is yes. EDIT : https://nai.nasa.gov/annual-reports/2002/uw/giant-impacts-in-earths-early-history-reseeding-the-planet-and-the-search-for-earth-rocks-on-the-moon/ " Project Progress We explore the likelihood that early remains of Earth, Mars, and Venus have been preserved on the Moon in high enough concentrations to motivate a search mission. During the Late Heavy Bombardment, the inner planets experienced frequent large impacts. Material ejected by these impacts near the escape velocity would have had the potential to land and be preserved on the surface of the Moon. In order to determine whether the Moon has preserved enough ejecta to justify a search mission, we calculate the amount of Terran material incident on the Moon over its history by considering the distribution of ejecta launched from the Earth by large impacts. In addition, we make analogous estimates for Mars and Venus. We find, for a well mixed regolith, that the median surface abundance of Terran material is roughly 7 ppm, corresponding to a mass of approximately 20,000 kg of Terran material over a 10 × 10 square km area Mounting attention has focused on interplanetary transfer of microorganisms (panspermia), particularly in reference to exchange between Mars and Earth. In most cases, however, such exchange requires millions of years, over which time the transported microorganisms must remain viable. During a large impact on Earth, however, previous work (Armstrong et al., submitted) has shown that substantial amounts of material return to the planet of origin over a much shorter period of time (< 5000 years), considerably mitigating the challenges to the survival of a living organism. Conservatively evaluating experiments performed on Bacillus subtilis and Deinococcus radiodurans to constrain biological survival under impact conditions, we estimate that if the Earth were hit by a sterilizing impactor ~ 300 km in diameter, with a relative velocity of 30 km s-1 (such as may have occurred during the Late Heavy Bombardment), an initial cell population in the ejecta of order 10-4 – 10-2 cells kg-1 would in most cases be sufficient for a single organism to survive and return to an again-clement planet 3000-5000 years later. Although little can be said about the characteristics or distribution of ancient life, our calculations suggest that impact re-seeding is a possible means by which life, if present, could have survived the Late Heavy Bombardment."