Our growing understanding of extremophiles here on Earth has opened up new possibilities in astrobiology. Scientists are taking another look at resource-poor worlds that appeared like they could never support life. One team of researchers is studying a nutrient-poor region of Mexico to try to understand how organisms thrive in challenging environments.Continue reading “Nutrient-Poor and Energy-Starved. How Life Might Survive at the Extremes in the Solar System”
It is a foregone conclusion that if humanity intends to survive the so-called “Anthropocene” we need to make the transition away from fossil fuels and other methods that are unsustainable and amplify our impact on the planet. In this respect, a great deal of research and development is being directed towards “renewable energy.” Of the many methods that are being developed, the biggest contender is and always has been solar power.
Unfortunately, solar power suffers from a number of drawbacks, like the fact that it is only available during the day and favorable weather conditions. However, a new study by researchers from the Institute for Research in Electronics and Applied Physics (IREAP) shows how a special kind of photovoltaic cell could generate power at night. These “anti-solar” cells could revolutionize renewable energy and make it far more proficient.Continue reading “Anti-Solar Cells Could Generate Electricity at Night”
An ice shelf in Antarctica is about to give birth to a baby. This baby is a giant, spawned by growing cracks in the Brunt Ice Shelf. It’s not clear what this’ll mean to the scientific infrastructure in the area, and to the human presence, which were both established in the 1950s.Continue reading “Antarctica is About to Unleash an Iceberg Twice the Size of New York City”
Nothing lasts forever, especially an iceberg drifting away from its frigid home. This coffin-shaped iceberg was spotted by astronauts on the International Space Station as it drifted northwards. It split off from a much larger iceberg about 18 years ago, and is moving into warmer and warmer waters.
There’s nothing an astronomer – whether professional or amateur – loves more than a clear dark night sky away from the city lights. Outside the glare and glow and cloud cover that most of us experience every day, the night sky comes alive with a life of its own.
Thousands upon countless thousands of glittering jewels – each individual star a pinprick of light set against the velvet-smooth blackness of the deeper void. The arching band of the Milky Way, itself host to billions more stars so far away that we can only see their combined light from our vantage point. The familiar constellations, proudly showing their true character, drawing the eye and the mind to the ancient tales spun about them.
There are few places left in the world to see the sky as our ancestors did; to gaze in wonder at the celestial dome and feel the weight of billions of years of cosmic history hanging above us. Thankfully the International Dark Sky Association is working to preserve what’s left of the true night sky, and they’ve rightfully marked northern Chile to preserve for posterity.
Record-setting Hurricane Irma barreled over the Caribbean islands of St. Martin, St. Barthelemy and Anguilla early Wednesday, destroying buildings with its sustained winds of 185 mph (297 kph), with rains and storm surges causing major flooding. The US National Hurricane Center listed the Category 5 Irma as the strongest Atlantic hurricane ever recorded north of the Caribbean and east of the Gulf of Mexico. The storm continues to roar on a path toward the U.S. and British Virgin Islands, Puerto Rico and possibly Florida, or along the southeast coast of the US.
This animation of NOAA’s GOES East satellite imagery from Sept. 3 at 8:15 a.m. EDT (1215 UTC) to Sept. 6 ending at 8:15 a.m. EDT (1215 UTC) shows Category 5 Hurricane Irma as it moved west and track over St. Martin by 8 a.m. EDT on Sept. 6:
Different models have Irma traveling on slightly different paths and officials from all the areas that might possibly be hit are telling people to prepare and follow evacuation orders. National Hurricane Center scientist Eric Blake said via twitter that some models had the storm going one way, and some another. But he cautioned everyone in a potential path should take precautions. “Model trends can be quite misleading- could just change right back. It is all probabilistic at this point. It could still miss [one particular area]. But chances of an extreme event is rising.”
— Eric Blake ? (@EricBlake12) September 6, 2017
— NASA SPoRT (@NASA_SPoRT) September 6, 2017
The fleet of Earth-observing satellites are providing incredible views of this monster storm, and even astronauts on board the International Space Station are capturing views:
The International Space Station’s external cameras captured a dramatic view of Hurricane Irma as it moved across the Atlantic Ocean Sept. 5. pic.twitter.com/mc61pt2G8O
— Intl. Space Station (@Space_Station) September 5, 2017
— NOAA Satellites (@NOAASatellites) September 6, 2017
— NWS Twin Cities (@NWSTwinCities) September 6, 2017
— NASA SPoRT (@NASA_SPoRT) September 5, 2017
While satellite views provide the most comprehensive view of Irma’s potential track, there’s also a more ‘hands-on’ approach to getting data on hurricanes. NOAA hurricane hunter Nick Underwood posted this video while his plane flew into Hurricane Irma yesterday. The plane’s specialized instruments can take readings on the storm that forecasters can’t get anywhere else:
— Nick Underwood (@TheAstroNick) September 5, 2017
But Irma isn’t the only storm to keep an eye on. Tropical storms Katia and Jose are also on the horizon:
— NASA SPoRT (@NASA_SPoRT) September 6, 2017
In the meantime, a launch is scheduled from Cape Canaveral on Thursday, September 7. SpaceX is hoping to launch the US Air Force’s X-37B reusable spaceplane, but current forecasts put only a 50% chance of weather suitable enough on Thursday, and only 40% on Friday. We’ll keep you posted.
For the latest satellite views, the Twitter accounts above are posting regular updates.
ASTROTECH SPACE OPERATIONS/KENNEDY SPACE CENTER, FL – The last of NASA’s next generation Tracking and Data Relay Satellites (TRDS) designed to relay critical science data and research observations gathered by the International Space Station (ISS), Hubble and dozens of Earth-orbiting Earth science missions is undergoing final prelaunch clean room preparations on the Florida Space Coast while targeting an early August launch – even as the agency reviews the scheduling impact of a weekend “closeout incident” that “damaged” a key component.
Liftoff of NASA’s $408 million eerily insectoid-looking TDRS-M science relay comsat atop a United Launch Alliance (ULA) Atlas V rocket currently scheduled for August 3 may be in doubt following a July 14 work related incident causing damage to the satellite’s Omni S-band antenna while inside the Astrotech Space Operations facility in Titusville, Florida.
“The satellite’s Omni S-band antenna was damaged during final spacecraft closeout activities,” NASA said in an updated status statement provided to Universe Today earlier today, July 16. NASA did not provide any further details when asked.
Everything had been perfectly on track as of Thursday, July 13 as Universe Today participated in an up close media tour and briefing about the massive probe inside the clean room processing facility at Astrotech Space Operations in Titusville, Fl.
On July 13, technicians were busily working to complete final spacecraft processing activities before its encapsulation inside the nose cone of the ULA Atlas V rocket she will ride to space, planned for the next day on July 14. The satellite and pair of payload fairings were stacked in separate high bays at Astrotech on July 13.
Alas the unspecified “damage” to the TDRS-M Omni S-band antenna unfortunately took place on July 14.
TDRS-M was built by Boeing and engineers are now analyzing the damage in a team effort with NASA. However it’s not known exactly during which closeout activity or by whom the damage occurred.
ULA CEO Tory Bruno tweeted that his company is not responsible and referred all questions to NASA. This may indicate that the antennae was not damaged during the encapsulation procedures inside the ULA payload fairing halves.
“NASA and Boeing are reviewing an incident that occurred with the Tracking and Data Relay Satellite (TDRS-M) on July 14 at Astrotech Space Operations in Titusville, Florida. The satellite’s Omni S-band antenna was damaged during final spacecraft closeout activities” stated NASA.
TDRS-M looks like a giant insect – or a fish depending on your point of view. It was folded into flight configuration for encapsulation in the clean room and the huge pair of single access antennas resembled a cocoon or a cicada. The 15 foot diameter single access antennas are large parabolic-style antennas and are mechanically steerable.
What does TDRS do? Why is it important? How does it operate?
“The existing Space Network of satellites like TDRS provide constant communications from other NASA satellites like the ISS or Earth observing satellites like Aura, Aqua, Landsat that have high bandwidth data that needs to be transmitted to the ground,” TDRS Deputy Project Manager Robert Buchanan explained to Universe Today during an interview in the Astrotech clean room.
“TRDS tracks those satellites using antennas that articulate. Those user satellites send the data to TDRS, like TDRS-M we see here and nine other TDRS satellites on orbit now tracking those satellites.”
“That data acquired is then transmitted to a ground station complex at White Sands, New Mexico. Then the data is sent to wherever those user satellites want the data to be sent is needed, such as a science data ops center or analysis center.”
Once launched and deployed in space they will “take about 30 to 40 days to fully unfurl,” Buchanan told me in the Astrotech clean room.
Astrotech is located just a few miles down the road from NASA’s Kennedy Space Center and the KSC Visitor Complex housing the finest exhibits of numerous spaceships, hardware items and space artifacts.
At this time, the TDRS-M website countdown clock is still ticking down towards a ULA Atlas V blastoff on August 3 at 9:02 a.m. EDT (1302 GMT) from Space Launch Complex 41 (SLC-41) on Cape Canaveral Air Force Station, for a late breakfast delight.
The Aug. 3 launch window spans 40 minutes from 9:02 to 9:42 a.m. EDT.
Whether or not the launch date will change depends on the results of the review of the spacecraft’s health by NASA and Boeing. Several other satellites are also competing for launch slots in August.
“The mission team is currently assessing flight acceptance and schedule. TDRS-M is planned to launch Aug. 3, 2017, on an United Launch Alliance (ULA) Atlas V rocket from Cape Canaveral Air Force Station in Florida,” NASA explained.
TDRS-M, spacecraft, which stands for Tracking and Data Relay Satellite – M is NASA’s new and advanced science data relay communications satellite that will transmit research measurements and analysis gathered by the astronaut crews and instruments flying abroad the International Space Station (ISS), Hubble Space Telescope and over 35 NASA Earth science missions including MMS, GPM, Aura, Aqua, Landsat, Jason 2 and 3 and more.
The TDRS constellation orbits 22,300 miles above Earth and provide near-constant communication links between the ground and the orbiting satellites.
TRDS-M will have S-, Ku- and Ka-band capabilities. Ka has the capability to transmit as much as six-gigabytes of data per minute. That’s the equivalent of downloading almost 14,000 songs per minute says NASA.
The TDRS program is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
TDRS-M is the third satellite in the third series of NASA’s American’s most powerful and most advanced Tracking and Data Relay Satellites. It is designed to last for a 15 year orbital lifetime.
The first TDRS satellite was deployed from the Space Shuttle Challenger in 1983 as TDRS-A.
TDRS-M was built by prime contractor Boeing in El Segundo, California and is the third of a three satellite series – comprising TDRS -K, L, and M. They are based on the Boeing 601 series satellite bus and will be keep the TDRS satellite system operational through the 2020s.
TDSR-K and TDRS-L were launched in 2013 and 2014.
The Tracking and Data Relay Satellite project is managed at NASA’s Goddard Space Flight Center.
TDRS-M was built as a follow on and replacement satellite necessary to maintain and expand NASA’s Space Network, according to a NASA description.
The gigantic satellite is about as long as two school buses and measures 21 meters in length by 13.1 meters wide.
It has a dry mass of 1800 kg (4000 lbs) and a fueled mass of 3,454 kilogram (7,615 lb) at launch.
TDRS-M will blastoff on a ULA Atlas V in the baseline 401 configuration, with no augmentation of solid rocket boosters on the first stage. The payload fairing is 4 meters (13.1 feet) in diameter and the upper stage is powered by a single-engine Centaur.
TDRS-M will be launched to a Geostationary orbit some 22,300 miles (35,800 km) above Earth.
“The final orbital location for TDRS-M has not yet been determined,” Buchanen told me.
The Atlas V booster is being assembled inside the Vertical Integration Facility (VIF) at SLC-41 and will be rolled out to the launch pad the day before liftoff with the TDRS-M science relay comsat comfortably encapsulated inside the nose cone.
Carefully secured inside its shipping container, the TDRS-M satellite was transported on June 23 by a US Air Force cargo aircraft from Boeing’s El Segundo, California facility to Space Coast Regional Airport in Titusville, Florida, for preflight processing at Astrotech.
Watch for Ken’s onsite TDRS-M and space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
KENNEDY SPACE CENTER, FL – After threatening stormy skies over the Florida Space Coast miraculously parted just in the nick of time, the first ever recycled SpaceX Dragon cargo freighter blasted off on the 100th flight from historic pad 39A on the Kennedy Space Center (KSC) late Saturday afternoon June 3 – bound for the International Space Station (ISS) loaded with a science rich cargo from NASA for the multinational crew.
Nearly simultaneously the first stage booster accomplished another heart stopping and stupendous ground landing back at the Cape accompanied by multiple shockingly loud sonic booms screeching out dozens of miles (km) in all directions across the space coast region.
Liftoff of the SpaceX Falcon 9 rocket carrying the unmanned Dragon cargo freighter from seaside Launch Complex 39A at KSC in Florida took place during an instantaneous launch window at 5:07 p.m. EDT Saturday, June 3, after a predicted downpour held off just long enough for the SpaceX launch team to get the rocket safely off the ground.
The launch took place after a 48 hour scrub from Thursday June 1 forced by stormy weather and lightning strikes came within 10 miles of pad 39A less than 30 minutes from the planned liftoff time.
The backup crew of 40 new micestonauts are also aboard for a first of its kind osteoporosis science study – that seeks to stem the loss of bone density afflicting millions of people on Earth and astronauts crews in space by testing an experimental drug called NELL-1. The 40 originally designated mice lost their coveted slot and were swapped out Friday due to the scrub.
The 213-foot-tall (65-meter-tall) SpaceX Falcon 9 roared to life off pad 39A upon ignition of the 9 Merlin 1 D first stage engines generating 1.7 million pounds of liftoff thrust and successfully delivered the Dragon bolted on top to low Earth orbit on course for the space station and jam packed with three tons of essential cargo.
Loading of the densified liquid oxygen and RP-1 propellants into the Falcon 9 first and second stages starting about 70 minutes prior to ignition. Everything went off without a hitch.
Dragon reached its preliminary orbit 10 minutes after launch and deployed its power generating solar arrays. It now set out on a carefully choreographed series of thruster firings to reach the space station Monday morning.
Following stage separation at 2 min 25 sec after liftoff, the first stage began a series of three burns (boostback, entry and landing) to carry out a precision propulsive ground landing back at Cape Canaveral Air Force Station, FL at Landing Zone-1 (LZ-1).
The 156-foot-tall (47-meter-tall) first stage successfully touched down upright at LZ-1 some 8 minutes after liftoff as I witnessed from the NASA Causeway and seen in photos from myself and colleagues herein.
LZ-1 is located about 9 miles (14 kilometers) south of the starting point at pad 39A.
Thus overall SpaceX has now successfully recovered 11 boosters; 5 by land and 6 by sea, over the past 18 months – in a feat straight out of science fiction but aimed at drastically slashing the cost of access to space as envisioned by SpaceX billionaire CEO and founder Elon Musk.
Another significant milestone for this flight is that it features the first reuse of a previously launched Dragon. It previously launched on the CRS-4 resupply mission.
The recycled Dragon has undergone some refurbishments to requalify it for flight but most of the structure is intact, according to SpaceX VP for Mission Assurance Hans Koenigsmann.
The 20-foot high, 12-foot-diameter Dragon is carrying almost 5,970 pounds of science experiments and research instruments, crew supplies, food water, clothing, hardware, gear and spare parts to the million pound orbiting laboratory complex. This will support over 62 of the 250 research investigations and experiments being conducted by Expedition 52 and 53 crew members.
See detailed CRS-11 cargo mission cargo below.
Dragon CRS-11 marks SpaceX’s eleventh contracted commercial resupply services (CRS) mission to the International Space Station for NASA since 2012.
Falcon 9 streaked to orbit in spectacular fashion darting in and out of clouds for the hordes of onlookers and spectators who had gathered from around the globe to witness the spectacle of a rocket launch and booster landing first hand.
Dragon is loaded with “major experiments that will look into the human body and out into the galaxy.”
The flight will deliver investigations and facilities that study neutron stars, osteoporosis, solar panels, tools for Earth-observation, and more.
The unpressurized trunk of the spacecraft also will transport 3 payloads for science and technology experiments and demonstrations.
The truck payloads include the Roll-Out Solar Array (ROSA) solar panels, the Multiple User System for Earth Sensing (MUSES) facility which hosts Earth-viewing instruments and tools for Earth-observation and equipment to study neutron stars with the Neutron Star Interior Composition Explorer (NICER) payload.
NICER is the first ever space mission to study the rapidly spinning neutron stars – the densest objects in the universe. The launch coincidentally comes nearly 50 years after they were discovered by British astrophysicist Jocelyn Bell.
A second objective of NICER involves the first space test attempting to use pulsars as navigation beacons through technology called Station Explorer for X-Ray Timing and Navigation (SEXTANT).
If all goes well, Dragon will arrive at the ISS 2 days after launch and be grappled by Expedition 52 astronauts Peggy Whitson and Jack Fischer using the 57.7 foot long (17.6 meter long) Canadian-built robotic arm.
They will berth Dragon at the Earth-facing port of the Harmony module.
NASA TV will begin covering the Dragon rendezvous and grappling activities starting at 8:30 a.m. Monday.
Dragon CRS-11 is SpaceX’s second contracted resupply mission to launch this year for NASA.
The prior SpaceX cargo ship launched on Feb 19, 2017 on the CRS-10 mission to the space station. CRS-10 is further noteworthy as being the first SpaceX launch of a Falcon 9 from NASA’s historic pad 39A.
Overall CRS-11 marks the 100th launch from pad 39A and the sixth SpaceX launch from this pad.
SpaceX leased pad 39A from NASA in 2014 and after refurbishments placed the pad back in service this year for the first time since the retirement of the space shuttles in 2011. To date this is the sixth SpaceX launch from this pad.
Previous launches include 11 Apollo flights, the launch of the unmanned Skylab in 1973, 82 shuttle flights and five SpaceX launches.
Cargo Manifest for CRS-11:
TOTAL CARGO: 5970.1 lbs. / 2708 kg
TOTAL PRESSURIZED CARGO WITH PACKAGING: 3761.1 lbs. / 1665 kg
• Science Investigations 2356.7 lbs. / 1069 kg
• Crew Supplies 533.5 lbs. / 242 kg
• Vehicle Hardware 438.7 lbs. / 199 kg
• Spacewalk Equipment 123.4 lbs. / 56 kg
• Computer Resources 59.4 lbs. / 27 kg
UNPRESSURIZED 2209.0 lbs. / 1002 kg
• Roll-Out Solar Array (ROSA) 716.5 lbs. / 325 kg
• Neutron Star Interior Composition Explorer (NICER) 820.1 lbs. / 372 kg
• Multiple User System for Earth Sensing (MUSES) 672.4 lbs. / 305 kg
Watch for Ken’s onsite CRS-11 mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Hydrogen is the most abundant element in the Universe. But here on Earth, it’s rather rare. That’s unfortunate, because in our warming world, its status as an emissions-free fuel makes it a coveted chemical. If German researchers are successful, their Synlight project will help make renewable hydrogen fuel a reality.
Dubbed the “artificial Sun”, the Synlight uses concentrated light to power Thermochemical Water Splitting (TWS.) Every school child knows you can produce hydrogen by electrolysis—running an electric current through water. But that takes an enormous amount of electricity. TWS might be a better way of getting hydrogen out of water, but it takes an enormous amount of energy too, and that’s what the German research is about.
When combusted with pure oxygen—inside a fuel cell for example—hydrogen’s only waste product is water. No greenhouse gases or particulates are produced. But if we want to use it to power our cars, buses, trucks, and even airplanes, we need enormous amounts of it. And we need to produce it cost-effectively.
“Renewable energies will be the mainstay of global power supply in the future.” – Karsten Lemmer DLR Executive Board Member
The idea is to use the heat generated by Concentrated Solar Power (CSP) to extract hydrogen from water, thereby eliminating the need for electricity. CSP systems use mirrors or lenses to concentrate a large area of sunlight into a small area. The heat from that action can be used to power TWS. The Synlight project in Germany is demonstrating the viability of TWS by mimicking the effect of concentrated sunlight. In doing so, researchers there are building what’s being called the world’s largest artificial Sun.
German researchers at the German Aerospace Center (DLR) at Julich near Cologne built the Synlight, a system of 149, high power lamps of the type used in film projections. When all these lamps are turned on, Synlight produces light that is about 10,000 times more intense than natural sunlight on Earth. When all the lamps are aimed at a single spot, Synlight generates temperatures up to 3000 Celsius. The challenge now is to develop materials and processes that can operate in such an extreme temperature.
The Synlight system itself uses an enormous amount of electrical power to operate. But that’s often the case with experimental facilities. The Synlight project will mimic the effect of intense, continuous solar energy, something that is not readily available in Germany. By building a test facility powered by electricity, researchers will be able to reliably perform experiments without being delayed or affected by cloudy weather.
“Fuels, propellants and combustibles acquired using solar power offer immense potential for long-term storage and the production of chemical raw materials, and the reduction of carbon dioxide emissions. Synlight will enhance our research in this field.” – Karsten Lemmer, DLR Executive Board Member
As Johannes Remmel, the North Rhine-Westphalia Minister for Climate Protection, said, “”We need to expand existing technology in practical ways in order to achieve renewable energy targets, but the energy transition will falter without investments in innovative research, in state-of-the-art technologies and in global lighthouse projects like Synlight.”
This is not the German Aerospace Center’s first foray in concentrated solar power. They’re involved in a number of projects to advance concentrated solar power and thermal water splitting. The DLR is a partner in the Hydrosol II pilot in Spain. It’s a reactor for solar thermochemical hydrogen production that has been in operation since 2008. They’re also involved in the first commercially operated solar tower plant, an 11 megawatt system in Spain called the PS10 solar power tower.
Scientists have known for some time that the Earth goes through cycles of climatic change. Owing to changes in Earth’s orbit, geological factors, and/or changes in Solar output, Earth occasionally experiences significant reductions in its surface and atmospheric temperatures. This results in long-term periods of glaciation, or what is more colloquially known as an “ice age”.
These periods are characterized by the growth and expansion of ice sheets across the Earth’s surface, which occurs every few million years. By definition we are still in the last great ice age – which began during the late Pliocene epoch (ca. 2.58 million years ago) – and are currently in an interglacial period, characterized by the retreat of glaciers.
While the term “ice age” is sometime used liberally to refer to cold periods in Earth’s history, this tends to belie the complexity of glacial periods. The most accurate definition would be that ice ages are periods when ice sheets and glaciers expand across the planet, which correspond to significant drops in global temperatures and can last for millions of years.
During an ice age, there are significant temperature differences between the equator and the poles, and temperatures at deep-sea levels have also been shown to drop. This allows for large glaciers (comparable to continents) to expand, covering much of the surface area of the planet. Since the Pre-Cambrian Era (ca. 600 million years ago), ice ages have occurred at widely space intervals about about 200 million years.
History of Study:
The first scientist to theorize about past glacial periods was the 18th century Swiss engineer and geographer Pierre Martel. In 1742, while visiting an Alpine valley, he wrote about the dispersal of large rocks in erratic formations, which the locals attributed to the glaciers having once extended much further. Similar explanations began to emerge in the ensuing decades for similar patterns of boulder distribution in other parts of he world.
From the middle of the 18th century onward, European scholars increasingly began to contemplate ice as a means of transporting rocky material. This included the presence of boulders in coastal areas in the Baltic states and the Scandinavian peninsula. However, it was Danish-Norwegian geologist Jens Esmark (1762–1839) who first argued the existence of a sequence of world wide ice ages.
This theory was detailed in a paper he published in 1824, in which he proposed that changes in Earth’s climate (which were due to changes in its orbit) were responsible. This was followed in 1832 by German geologist and forestry professor Albrecht Reinhard Bernhardi speculating about how the polar ice caps may have once reached as far as the temperate zones of the world.
At this same time, German botanist Karl Friedrich Schimper and Swiss-American biologist Louis Agassiz began independently developing their own theory about global glaciation, which led toSchimper coining the term “ice age” in 1837. By the late 19th century, ice age theory gradually began to gain widespread acceptance over the notion that the Earth cooled gradually from its original, molten state.
By the 20th century, Serbian polymath Milutin Milankovic developed his concept of Milankovic cycles, which linked long-term climate changes to periodic changes in the Earth’s orbit around the Sun. This offered a demonstrable explanation for ice ages, and allowed scientists to make predictions about when significant changes in Earth’s climate might occur again.
Evidence for Ice Ages:
There are three forms of evidence for ice age theory, which range from the geological and the chemical to the paleontological (i.e. the fossil record). Each has its particular benefits and drawbacks, and has helped scientists to develop a general understanding of the effect ice ages have had on geological record for the past few billion years.
Geological: Geological evidence includes rock scouring and scratching, carved valleys, the formation of peculiar types of ridges, and the deposition of unconsolidated material (moraines) and large rocks in erratic formations. While this sort of evidence is what led to ice age theory in the first place, it remains temperamental.
For one, successive glaciation periods have different effects on a region, which tends to distort or erase geological evidence over time. In addition, geological evidence is difficult to date exactly, causing problems when it comes to getting an accurate assessment of how long glacial and interglacial periods have lasted.
Chemical: This consists largely of variations in the ratios of isotopes in fossils discovered in sediment and rock samples. For more recent glacial periods, ice cores are used to construct a global temperature record, largely from the presence of heavier isotopes (which lead to higher evaporation temperatures). They often contain bubbles of air as well, which are examined to assess the composition of the atmosphere at the time.
Limitations arise from various factors, however. Foremost among these are isotope ratios, which can have a confounding effect on accurate dating. But as far as the most recent glacial and interglacial periods are concerned (i.e. during the past few million years), ice core and ocean sediment core samples remain the most trusted form of evidence.
Paleontological: This evidence consists of changes in the geographical distribution of fossils. Basically, organisms that thrive in warmer conditions become extinct during glacial periods (or become highly restricted in lower latitudes), while cold-adapted organisms thrive in these same latitudes. Ergo, reduced amounts of fossils in higher latitudes is an indication of the spread of glacial ice sheets.
This evidence can also be difficult to interpret because it requires that the fossils be relevant to the geological period under study. It also requires that sediments over wide ranges of latitudes and long periods of time show a distinct correlation (due to changes in the Earth’s crust over time). In addition, there are many ancient organisms that have shown the ability to survive changes in conditions for millions of years.
As a result, scientists rely on a combined approach and multiple lines of evidence wherever possible.
Causes of Ice Ages:
The scientific consensus is that several factors contribute to the onset of ice ages. These include changes in Earth’s orbit around the Sun, the motion of tectonic plates, variations in Solar output, changes in atmospheric composition, volcanic activity, and even the impact of large meteorites. Many of these are interrelated, and the exact role that each play is subject to debate.
Earth’s Orbit: Essentially, Earth’s orbit around the Sun is subject to cyclic variations over time, a phenomenon also known as Milankovic (or Milankovitch) cycles. These are characterized by changing distances from the Sun, the precession of the Earth’s axis, and the changing tilt of the Earth’s axis – all of which result in a redistribution of the sunlight received by the Earth.
The most compelling evidence for Milankovic orbital forcing corresponds closely to the most recent (and studied) period in Earth’s history (circa. during the last 400,000 years). During this period, the timing of glacial and interglacial periods are so close to changes in Milankovic orbital forcing periods that it is the most widely accepted explanation for the last ice age.
Tectonic Plates: The geological record shows an apparent correlation between the onset of ice ages and the positions of the Earth’s continents. During these periods, they were in positions which disrupted or blocked the flow of warm water to the poles, thus allowing ice sheets to form.
This in turn increased the Earth’s albedo, which reduces the amount of solar energy absorbed by the Earth’s atmosphere and crust. This resulted in a positive feedback loop, where the advance of ice sheets further increased the Earth’s albedo and allowed for more cooling and more glaciation. This would continue until the onset of a greenhouse effect ended the period of glaciation.
Based on past ice-ages, three configurations have been identified that could lead to an ice age – a continent sitting atop the Earth’s pole (as Antarctica does today); a polar sea being land-locked (as the Arctic Ocean is today); and a super continent covering most of the equator (as Rodinia did during the Cryogenian period).
In addition, some scientists believe that the Himalayan mountain chain – which formed 70 million years ago – has played a major role in the most recent ice age. By increasing the Earth’s total rainfall, it has also increased the rate at which CO² has been removed from the atmosphere (thereby decreasing the greenhouse effect). Its existence has also paralleled the long-term decrease in Earth’s average temperature over the past 40 million years.
Atmospheric Composition: There is evidence that levels of greenhouse gases fall with the advance of ice sheets and rise with their retreat. According to the “Snowball Earth” hypothesis – in which ice completely or very nearly covered the planet at least once in the past – the ice age of the late Proterozoic was ended by an increase in CO² levels in the atmosphere, which was attributed to volcanic eruptions.
However, there are those who suggest that increased levels of carbon dioxide may have served as a feedback mechanism, rather than the cause. For example, in 2009, an international team of scientists produced a study – titled “The Last Glacial Maximum” – that indicated that an increase in solar irradiance (i.e. energy absorbed from the Sun) provided the initial change, whereas greenhouse gases accounted for the magnitude of change.
Major Ice Ages:
Scientists have determined that at least five major ice ages took place in Earth’s history. These include the Huronian, Cryogenian, Andean-Saharan, Karoo, and the Qauternary ice ages. The Huronian Ice Age is dated to the early Protzerozoic Eon, roughly 2.4 to 2.1 billion years ago, based on geological evidence observed to the north and north-east of Lake Huron (and correlated to deposits found in Michigan and Western Australia).
The Cryogenian Ice Age lasted from roughly 850 to 630 million years ago, and was perhaps the most severe in Earth’s history. It is believed that during this period, the glacial ice sheets reached the equator, thus leading to a “Snowball Earth” scenario. It is also believed that ended due to a sudden increase in volcanic activity that triggered a greenhouse effect, though (as noted) this is subject to debate.
The Andean-Saharan Ice Age occurred during the Late Ordovician and the Silurian period (roughly 460 to 420 million years ago). As the name suggests, the evidence here is based on geological samples take from the Tassili n’Ajjer mountain range in the western Sahara, and correlated by evidence obtained from the Andean mountain chain in South America (as well as the Arabian peninsula and the south Amazon basin).
The Karoo Ice Age is attributed to the evolution of land plants during the onset of the Devonian period (ca. 360 to 260 million years ago) which caused a long-term increase in planetary oxygen levels and a reduction in CO² levels – leading to global cooling. It is named after sedimentary deposits that were discovered in the Karoo region of South Africa, with correlating evidence found in Argentina.
The current ice age, known as the Pliocene-Quaternary glaciation, started about 2.58 million years ago during the late Pliocene, when the spread of ice sheets in the Northern Hemisphere began. Since then, the world has experienced several glacial and interglacial periods, where ice sheets advance and retreat on time scales of 40,000 to 100,000 years.
The Earth is currently in an interglacial period, and the last glacial period ended about 10,000 years ago. What remains of the continental ice sheets that once stretched across the globe are now restricted to Greenland and Antarctic, as well as smaller glaciers – like the one that covers Baffin Island.
Anthropogenic Climate Change:
The exact role played by all the mechanisms that ice ages are attributed to – i.e. orbital forcing, solar forcing, geological and volcanic activity – are not yet entirely understood. However, given the role of carbon dioxide and other greenhouse gas emissions, there has been a great deal of concern in recent decades what long-term effects human activity will have on the planet.
For instance, in at least two major ice ages, the Cryogenian and Karoo Ice Ages, increases and decreases in atmospheric greenhouse gases are believed to have played a major role. In all other cases, where orbital forcing is believed to be the primary cause of an ice age ending, increased greenhouse gas emissions were still responsible for the negative feedback that led to even greater increases in temperature.
The addition of CO2 by human activity has also played a direct role in climatic changes taking place around the world. Currently, the burning of fossil fuels by humans constitutes the largest source of emissions of carbon dioxide (about 90%) worldwide, which is one of the main greenhouse gases that allows radiative forcing (aka. the Greenhouse Effect) to take place.
In 2013, the National Oceanic and Atmospheric Administration announced that CO² levels in the upper atmosphere reached 400 parts per million (ppm) for the first time since measurements began in the 19th century. Based on the current rate at which emissions are growing, NASA estimates that carbon levels could reach between 550 to 800 ppm in the coming century.
If the former scenario is the case, NASA anticipates a rise of 2.5 °C (4.5 °F) in average global temperatures, which would be sustainable. However, should the latter scenario prove to be the case, global temperatures will rise by an average of 4.5 °C (8 °F), which would make life untenable for many parts of the planet. For this reason, alternatives are being sought out for development and widespread commercial adoption.
What’s more, according to a 2012 research study published in Nature Geoscience – titled “Determining the natural length of the current interglacial” – human emissions of CO² are also expected to defer the next ice age. Using data on Earth’s orbit to calculate the length of interglacial periods, the research team concluded that the next ice (expected in 1500 years) would require atmospheric CO² levels to remain beneath around 240?ppm.
Learning more about the longer ice ages as well the shorter glacial periods that have taken place in Earth’s past is important step towards understanding how Earth’s climate changes over time. This is especially important as scientists seek to determine how much of modern climate change is man-made, and what possible counter-measures can be developed.
We have written many articles about the Ice Age for Universe Today. Here’s New Study Reveals Little Ice Age Driven by Volcanism, Did a Killer Asteroid Drive the Planet into an Ice Age?, Was There a Slushball Earth?, and Is Mars Coming out of an Ice Age?