Comet Composition
Light Analysis. Light from a comet can identify some of the dust and gases in its head and tail. Each type of molecule, or portion thereof, absorbs and emits specific colors of light. When this light passes through a prism or other instrument, its spectrum (looking like a long stretched-out bar code) identifies the gases the light passed through. Even light frequencies humans cannot see can be analyzed in the tiniest detail. Some components, like sodium, are easy to identify, but others, such as chlorine, are difficult, because their light is dim or masked by other radiations.
Curved tails in comets have the same specific colors as the Sun; therefore, those tails must contain solid particles (dust) which are reflecting sunlight. Also detected in comets are water, carbon dioxide, argon,35 and many combinations of hydrogen, carbon, oxygen, and nitrogen. Some molecules in comets, such as water and carbon dioxide, have broken apart and recombined to produce many other compounds. Comets contain trace amounts of methane, ethane, and the amino acid glycine (a building block of life on Earth). On Earth, bacteria produce almost all methane, and ethane comes from methane. How could comets originating in space get high concentrations of these compounds? 36
Plumes of methane are seen escaping up into Mars’ atmosphere from a few locations,37 but sunlight destroys methane in Mars’ atmosphere within a few centuries, so something within Mars must be producing methane.38 Martian volcanoes are not, because Mars has no active or recent volcanoes. Nor do comets today deliver methane fast enough to replace what solar radiation is destroying. 39
Furthermore, the methane concentration in Mars’ atmosphere is seasonally cyclic.40 It increases in the Martian summer and decreases in the Martian winter, implying that something living, whose metabolism increases in the summer and decreased in the winter, is producing that methane. This has been observed by the Mars rover, Curiosity, for 5 Earth years (3 Martian years) since Curiosity landed on Mars in 2012. Does this mean that bacterial life is in Martian soil? 40 Most likely. [See “Is There Life in Outer Space?” on page 531.] Later in this chapter, a surprising explanation will be given. (Also, complex organic molecules that probably came recently from life have been found on Mars.41)
Dust particles in comets vary in size from pebbles to specks smaller than the eye can detect. How dust could ever form comets in space is a recognized mystery.42 Light analysis shows that the atoms in comet dust are arranged in simple, repetitive, crystalline patterns, primarily that of olivine,43 the most common of the approximately 2,500 known minerals on Earth. The type of olivine in comet dust appears to be rich in magnesium, as is the olivine in rocks beneath oceans and in continental crust. In contrast, interstellar dust does not appear to be crystalline.
Crystalline patterns form because atoms and ions tend to arrange themselves in patterns that minimize their total energy. An atom whose temperature and pressure allow it to move about will eventually find a “comfortable” slot (next to other atoms) that minimizes energy. (This is similar to the motion of marbles rolling around on a table filled with little pits. A marble is most “comfortable” when it settles into one of the pits. The lower the marble settles, the lower its energy, and the more permanent its position.) Minerals in rocks, such as in the mantle or deep in Earth’s crust, have been under enough pressure to develop a crystalline pattern.44
Deep Impact Mission. On 4 July 2005, the Deep Impact spacecraft fired an 820-pound “bullet” into comet Tempel 1, revealing as never before the composition of a comet’s surface layers.45 The cometary material blasted into space included:
a. silicates, which constitute about 95% of the Earth’s crust and contain considerable oxygen; both are rare in the near vacuum of space
b. crystalline silicates that could not have formed in frigid (about - 450°F) outer space unless the temperature reached 1,300°F and then slowly cooled under some pressure
c. minerals that apparently form only in liquid water,46 such as calcium carbonates (limestone) and clays
d. organic material of unknown origin
e. sodium, which is seldom seen in space
f. very fine dirt—like talcum powder—that was “tens of meters deep” on the comet’s surface
Comet Tempel 1 is fluffy and extremely porous. It contains about 60% empty space, and has “the strength of the meringue in lemon meringue pie.”47 “Researchers now estimate that 15% of [comet 67P] is made up of fluffy particles, which are 99.95 empty space.” 48
On 4 November 2010, the Deep Impact spacecraft passed by comet Hartley 2 and found that the most abundant gas being expelled was carbon dioxide (CO2). [To understand this, see "Why Do Comets have so Much Carbon Dioxide?" Also see Figure 191 on page 348.]
Stardust Mission. In July 2004, NASA’s Stardust mission passed within 150 miles of comet Wild 2 (pronounced “Vilt 2”), caught dust particles from its tail, and returned them to Earth in January 2006. The dust was crystalline and contained “abundant organics” 1 (and even the amino acid glycine 50), water molecules, and many chemical elements common on Earth but, compared to hydrogen and helium, rare in space: magnesium, calcium, aluminum, titanium, and sulfur. Crystalline material—minerals—should not form in the cold weightlessness of outer space.51
PREDICTION 28: Comet ice that has never melted will contain dissolved CO2.
In 2011, it was announced that Wild 2 contained the mineral cubanite that forms only in the presence of scalding hot liquid water: 122°F – 392°F. According to all standard explanations for comets, it is impossible to form liquid water inside a comet.52 Besides, liquid water cannot reach those extremely hot temperatures in a comet’s low-pressure environment ! Indeed, even cold liquid water inside comets will instantly flash into steam, leaving a remnant of ice. Something very unique must have happened.
The discovery [in Comet Wild 2] of minerals requiring [scalding] liquid water for their formation challenges the paradigm of comets as “dirty snowballs” frozen in time.53
The only explanation for the minerals found by the Deep Impact and Wild 2 missions is that they formed in the extremely hot, high-pressure, subterranean water chamber.
Rosetta Mission. On 12 November 2014, the European Space Agency’s Rosetta spacecraft landed instruments on Comet 67P/Churyumov-Gerasimenko—a comet that is 72%–74% empty space. This was the first successful landing on a comet. Among the many discoveries were sixteen organic compounds, shown in Table 13.54
Some will say that these organic compounds were precursors to life on Earth. Neglected is the more likely alternative: these compounds were fragments of organisms living on Earth that were destroyed in some cataclysm. If you saw a large pile of bricks mixed with steel, tubes, glass, wire, and insulation, would you conclude that a building was evolving or that a building had been destroyed?
Finding so many complex organic compounds on such a small body in space is unprecedented. On rare occasions an organic compound (a molecule containing carbon atoms in rings or long chains with such elements as hydrogen, oxygen, and nitrogen attached) might be found near a distant star. Comet 67P contained sixteen complex organic compounds! They, and especially the fifty samples of the amino acid (glycine) that were found, obviously came from life.
Molecular Oxygen (O2). Comet 67P’s atmosphere also contained molecular oxygen (O2)—two oxygen atoms linked together. Scientists were stunned! O2 should not have been there, because O2 should not be in space55 and it readily breaks apart and reacts with other chemicals to form compounds such as water, carbon dioxide, carbon monoxide. When it reacts with itself, it forms ozone (O3). No ozone was on 67P. Molecular oxygen is what we breathe on Earth and is relatively rare except on Earth. Earth’s surface waters are saturated with dissolved molecular oxygen.
The amount of O2 in 67P’s atmosphere was strongly correlated with the amount of water vapor in the comet’s atmosphere; the more water vapor that escaped from inside the comet as it warmed during the comet’s daytime and as it approached the Sun, the more O2 entered 67P’s atmosphere. Therefore, molecular oxygen was already dissolved in the water ice when the comet formed.
O2 was incorporated into the nucleus during the comet’s formation, ... Current Solar System formation models do not predict conditions that would allow this to occur.56
This explains why O2 did not have a chance to combine with hydrogen, carbon, or 67P’s complex organic compounds (listed above in Table 13) to form water, carbon dioxide, or carbon monoxide. It also tells us that the ice particles had to merge gently when the comet formed.
Comet 67P must have been put together gently, [Andre] Bieler says; otherwise the ice-coated grains that make up its bulk would have been heated and the oxygen removed.57
If comets formed billions of years ago, how could that O2 remain locked up in ice for all that time—through the formation of the solar system and comets, after innumerable impacts (from rocks to photons), and after millions of passes by the Sun? Kathrin Altwegg of the University of Bern, who coauthored this surprising report in the journal Nature admitted, “We never thought that oxygen could ‘survive’ for billions of years.” 58 [Correct. Molecular oxygen could not survive for billions of years in outer space. W.B.]
If comets brought the chemicals for life to Earth, why didn’t the O2 gobble up those chemicals long before they reached Earth? We all know what O2 does to dead bodies.
What is “Interstellar Dust”? Is it dust? Is it interstellar? While some of its light characteristics match those of dust, Hoyle and Wickramasinghe have shown that those characteristics have a much better match with dried, frozen bacteria and cellulose—an amazing match.59
Dust, cellulose, and bacteria may be in space, but each raises questions. If it is dust, how did dust form in space? “Cosmic abundances of magnesium and silicon [major constituents of dust] seem inadequate to give interstellar dust.” 60 A standard explanation is that exploding stars (supernovas) produced dust. However, supernovas radiate the energy of about 10 billion suns, so any expelled dust or nearby rocks would vaporize. If it is cellulose, the most abundant organic substance on Earth, how could such a large, complex molecule form in space? 61 Vegetation is one-third cellulose; wood is one-half cellulose. Finally, bacteria are so complex it is absurd to think they formed in space. How could they eat, keep from freezing, or avoid being destroyed by ultraviolet radiation?
Is all “interstellar dust” interstellar? Probably not. Starlight traveling to Earth passes through regions of space that absorb specific wavelengths of light. The regions showing the spectral characteristics of cellulose and bacteria may lie within or near the solar system. Some astronomers mistakenly assume that because much absorption occurs in interstellar space, little occurs in the solar system.
Heavy Hydrogen. Water molecules (H2O) have two hydrogen atoms and one oxygen atom. A hydrogen atom contains one proton in its nucleus. On Earth, about one out of 6,400 hydrogen nuclei has, besides its proton, a neutron, making that hydrogen twice as heavy as normal hydrogen. It is called heavy hydrogen, or deuterium.
Surprisingly, in most comets, one out of 3,200 hydrogen atoms is heavy—twice that in water on Earth.62 Therefore, comets did not deliver most of Earth’s water, as many writers have speculated. In comets, the ratio of heavy hydrogen to normal hydrogen is 20 –100 times greater than in interstellar space and the solar system as a whole.63 Evidently, comets came from an isolated reservoir rich in heavy hydrogen. Many efforts by comet experts to deal with this problem are simply unscientific guesswork. No known process will greatly increase or decrease the heavy hydrogen concentration in comets.