Archive for the 'Astronomy' Category

Oct 20 2017

Making Oxygen on Mars

Published by under Astronomy,Technology

Mars baseAt some point humans will travel to Mars. It seems inevitable, the only question being when that will happen. Optimists like Musk think it will happen before mid-century, but that may not be realistic. There are significant logistical hurdles without clear solutions.

Some argue, and I agree with this strategy, that we should focus first on a moon base. The moon is a lot closer, which solves many problems right there. But otherwise it would have many of the same challenges as Mars, and so if we develop a base on the moon we can use what we learn to be better able to tackle Mars. Further the moon can be a literal launching pad for Mars.

While Mars has some extra challenges, it may have some advantages as well over the moon. NASA experts have observed that Mars has just enough of an atmosphere to be a problem. It has 1% of the pressure of Earth, which means for astronauts it is functionally the same as a hard vacuum. You still need pressure suits, pressurized living spaces, and you need a supply of air to breath.

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15 responses so far

Oct 19 2017

More Gravitational Waves

Published by under Astronomy

neutronStar_drupal_withNOcaptionThe winner of the Nobel prize for physics was the detection of gravitational waves. These are extremely subtle ripples in spacetime caused by massive cataclysmic events, such as black holes colliding. These ripples were predicted by Einstein, who thought we may never be able to detect them because they would be so unbelievably tiny.

How tiny?  LIGO (Laser Interferometer Gravitational-Wave Observatory), the device used to detect the waves, can detect changes as small at 10 -22 meters. Graviational waves detected so far have had an amplitude of 10 -18 meters, smaller than the radius of a proton.

How is that possible? That is where the interferometry comes in. LIGO uses a laser split into two beams that will travel for 8 Km and then reflect off mirrors and come back to the same detector. The two beams have traveled the exact same distance so that they are in phase, or at least they can be calibrated to be exactly in phase, meaning that the peaks of the waves line up. When a ripple in spacetime comes through, the length of the two arms (which are at 90 degree angles to each other) will change slightly, bringing the two beams out of phase. That slight phase shift can be detected and measured.

Prior to winning the Nobel prize LIGO had detected four gravitational waves wash over it. This was considered enough of a confirmation of the technology and science to award the prize.

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Oct 10 2017

Half the Matter in the Universe Just Found

Published by under Astronomy

filamentsBy now most people are familiar with dark matter – that mysterious substance which has gravity but otherwise does not seem to interact with the normal matter with which we are most familiar. About 27% of the stuff (matter and energy) in the known universe is dark matter, 68% is dark energy, and only about 5% is made of known particles (baryons – protons, neutrons; leptons – electron; and more exotic particles).

We currently don’t know what dark matter is. We know it’s there because we can see its gravitational effect, first noticed because galaxies spin faster than they should. Based just on the gravity from stuff we can see, galaxies should be flying apart. They stick together because there is significantly more gravity than we can account for. There must be additional matter we can’t see, or dark matter.

It is perhaps less well-known that we also haven’t found about half of the normal matter that should exist in the universe. Even if we just consider that 5% that is made of standard particles, about half of it is missing. That is – until now, if recent reports are accurate.

This really wasn’t much of a mystery (not like dark matter) – astronomers suspected that the missing matter was present in the form of diffuse gas between galaxies. There is a lot of space out there, and even a wispy vapor could contain a lot of particles, as much as is contained in all the visible galaxies. The problem is, this thin gas is too wispy to see with conventional means.

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16 responses so far

Sep 15 2017

Cassini’s Dramatic End

Published by under Astronomy

Saturn- CassiniThe Cassini probe to Saturn has been considered one of the most successful space missions in history. Today it will plunge into the upper atmosphere of Saturn. As the atmosphere gets thicker on its way down the probe will begin to tumble from the turbulence, until it is ripped apart by the violent forces and finally melts in the intense heat of the gas giant. (As I am writing this there are just 30 minutes left.)

This is the intended fate of the probe. It was launched in 1997, took seven years to get to Saturn, and has been studying the planet and its moons for 13 years. It has dramatically improved our knowledge of the Saturn system. Cassini was the first probe to orbit Saturn. Prior to that, Pioneer and Voyager had performed flybys, which gave us quick glimpses but did not allow for extended study.

In addition to being a feat of science and engineering, Cassini surpassed expectations. Its original mission profile was for four years. It was able to have two mission extensions, for a total of 13 years. Now it is almost completely out of fuel – its mission is over.

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Aug 29 2017

40 Years of Voyager

Published by under Astronomy

voyager1_highOn August 20th 1977 Voyager 2 was launched. On September 5th Voyager 1 followed. The reason 2 launched before 1 is because V1 was on a faster trajectory and would arrive at Jupiter several months before V2, and NASA felt it would be easier not to have to explain endlessly to the media why V2 was arriving before V1. At present V1 is 12,959,246,289 miles from Earth, and V2 is 10,657,559,202 miles.

Voyager 1 is the farthest human made object from the Earth. If our civilization collapses tomorrow, the Voyager probes would be the longest surviving artifacts of our existence.

If you do not remember the Voyager missions, then think of what it was like for Horizon to fly by Pluto. Pluto went from a fuzzy blob to a detailed alien world. The Voyager missions were the same, except times four. This was our first closeup look at Jupiter, Saturn, Uranus and Neptune. It was our first closeup look at the large moons of Jupiter – Io, Ganymede, Europa and Callisto. We discovered even more smaller moons of Jupiter and Saturn. We discovered volcanic activity on Io, and that Jupiter has rings of its own.

Our knowledge of the outer solar system exploded, and we were rewarded with seemingly endless gorgeous pictures of these giant worlds and their companions.

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13 responses so far

Aug 21 2017

Solar Eclipse and Coincidence

solar-eclipse-2017Today there will be a total solar eclipse making its way all across the continental US, from Oregon to South Carolina. Unfortunately I could not logistically travel to see it first hand. I’ll have to wait for 2024, when another total solar eclipse will hit America, making a trail from Texas through upstate New York. Here in CT we will get 75% coverage, which will be cool but nothing (from what I hear) like seeing totality.

Eclipses are one of the testaments to the power of science. We can predict them with incredible accuracy, because we have worked out in tiny detail how planetary orbits work. We can make careful observation and combine that with accurate theories about how the universe works and mathematics to make calculations, and predict these celestial events far into the future.

Some people, however, choose to see the eclipse as a testament to the existence of God. I first heard this argument when I was in college – a friend of mine who was also a fundamentalist Christian essentially ridiculed me for thinking that eclipses were just coincidence. The hand of God was clearly at work.

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35 responses so far

Mar 10 2017

Fast Radio Bursts and Alien Life

Published by under Astronomy

frb-alienFast radio bursts (FRBs) are brief, bright, and distant bursts of radio emissions that are of unknown origin. Recently they have been in the news because of a paper which explores the feasibility that FRBs have an alien origin.

“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” said theorist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. “An artificial origin is worth contemplating and checking.”

Let me first give a little more background on FRBs and then we can discuss the alien hypothesis.

Fast Radio Bursts

The first thing to know about FRBs is that they are, indeed, fast. They typically last only a few milliseconds (thousandths of a second). Recorded FRBs range from 0.05 ms to 9.4 ms. That is extremely brief.

They are broadband radio bursts, meaning that they cover a broad frequency range.

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Mar 06 2017

Terraforming Mars

Published by under Astronomy

MarsTransitionVHow high a priority should we have for sending people to Mars? This seems to be a big question these days. NASA is developing the Space Launch System (SLS) and the Orion capsule specifically to have the capacity to send people to Mars. Elon Musk has stated that the real purpose of SpaceX is to colonize Mars.

The public imagination has also been sparked by movies such as The Martian (which was excellent). I also recommend National Geographics’ series “Mars” which is a combination of interviews with current scientists and engineers about the problems that a Mars colony would face, with a narrative about a future colonization mission.

The one fact that everyone agrees on is that colonizing Mars will be extremely difficult. Mars has an atmosphere about 1% that of Earth. This makes it just thick enough to be a problem but not thick enough to help with breaking while landing on Mars, and not thick enough to make the surface any more livable. A 1% atmosphere is effectively a vacuum, but it is enough to cause planet-wide dust storms that would make life on Mars challenging.

Transfer to Mars would take about 8 months with current rocket technology. Depending on the relative position of the planets and the transfer speed, 130-260 days are the figures most often cited. That means supply lines would be very difficult, and don’t expect any rescue missions.

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12 responses so far

Jan 27 2017

Scientists Create Metallic Hydrogen

jupiter-magnetic-fieldIt was just announced that for the first time scientists were able to create a small amount of metallic hydrogen in the lab. This is a significant breakthrough, and is sure to lead to further discovery, although it remains to be seen what specific practical applications may emerge.

Hydrogen, as most people know, is a gas at familiar temperatures and pressures. The universe is comprised of about 90% hydrogen. There is very little free hydrogen on the Earth, since it is a very light gas, but there is lots of hydrogen bound up in molecules, such as water.

In 1935, physicists Eugene Wigner and Hillard Bell Huntington hypothesized that under extreme pressure hydrogen atoms may form into a metal – metallic hydrogen. The point at which this happens was named the Wigner-Huntington transition, which explains the title of the recent paper. Metallic hydrogen can further be a liquid, in which the electrons and protons are free flowing, or they can form a crystalline structure and be a solid.

Astronomers infer that the core of Jupiter may be hot liquid hydrogen. We know that Jupiter is made mostly of hydrogen, and we can calculate that the pressure deep in Jupiter’s core must have millions of times the pressure on the surface of the Earth. That is sufficient pressure, according to theory, to compress hydrogen into its metallic form.

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19 responses so far

Oct 25 2016

234 Possible Alien Signals

Published by under Astronomy,Skepticism

alien-worldI love reading articles that discuss the same issue and come to essentially opposite conclusions. In this case, Canadian astronomers have recently performed an analysis of 2.5 million stars and found 234 of them producing pulsed signals that they claim may be of alien origin. The scientific community is skeptical.

The Independent declares, “Strange messages coming from the stars are ‘probably’ from aliens, scientists say.” Meanwhile, worldofwierdthings.com states, “Why hundreds of aliens probably aren’t trying to contact us.”

When you read deep into both articles you find a more nuanced position. The difference is mostly in the headline writing, but also in the overall emphasis of the article. Skepticism can be marginalized or central.

SETI and Skepticism

I have found the search for extraterrestrial intelligence (SETI) to be an excellent topic of skeptical discussion. It is a great forum for discussing what is legitimate science, and how scientists decide whether something is likely to be true or not. There is nothing supernatural or paranormal about life evolving on exoplanets, intelligence emerging, and developing a technological civilization that might send signals out into space. We have done it.

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71 responses so far

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