HUMANITY TO REACH MARS BY 2040?

Physics, Space, , , ,

by Móeiður Þorvaldsdóttir

NASA is planning for its top priority manned mission to Mars to be accomplished by the mid-2030s. This will follow three exploratory missions meant to investigate the long-term viability of humans surviving on Mars. Furthermore, these missions are necessary to develop and test necessary systems and equipment such as life support and spacecraft controls. These missions rely on the completion of NASA’s Space Launch System (SLS), the construction of which began in November 2014. SLS is a launch vehicle that will pave the way for more massive payloads than ever before. The manned mission is divided into two stages: the first one is planned to reach Mars’ moon Phobos by 2033 whilst the second part is expected to reach the surface of Mars by 2039.

A mosaic of Mars created from over 100 images taken by Viking Orbiters in the 1970s. Valles Marineris, the canyon seen in the centre, is the largest canyon in the Solar System. Image credit: NASA

The Plan

The three exploratory missions are named Earth Reliant, Proving Ground, and Earth Independent. Earth Reliant has already begun and is expected to continue until 2024. Proving Ground will start in 2018 when the Orion spacecraft will be launched on a lunar orbit using the SLS. The SLS in combination with other spacecraft has the capacity to help astronauts travel farther into space than ever before. The SLS has also been proposed as a launch vehicle for Uranian probe and Solar Probe 2, missions to Uranus and the Sun currently being planned. Orion’s first trip to the Moon will be unmanned, but, if this unmanned mission is successful astronauts will man Orion on a similar journey. This stage will test the capabilities of NASA’s team of astronauts, scientists and engineers as they attempt to redirect an asteroid into lunar orbit and extract samples for testing upon arrival back on Earth. Earth Independent will start with an unmanned trip to Mars in the 2020s that will test the capabilities of the vehicle for entry, descent and landing. It will also provide an opportunity to collect samples from the surface of Mars. This is NASA’s final exploratory mission, after which astronauts will begin their journey to the Red Planet.

Reaching Phobos

The trip to Phobos will require four launches of the SLS. The first of the four launches will carry a space tug which will use Solar Electric Propulsion (SEP) and two chemical propulsion payloads. The chemical propulsion payloads will be used to get the vehicle out of Earth’s influence and to land the vehicle on Phobos. The second SLS stage is planned to carry another SEP tug and the Phobos base. The Phobos base will be settled in order to provide a habitat for humans once on Phobos. It would also be possible to transport the base to different locations on Phobos if required. The next SLS launch will carry a deep-space habitat that is similar to the Phobos’ base as well as launch the vehicle into orbit around Mars. Finally, the last SLS stage will send a crew of four astronauts to Mars on board Orion. The Phobos Transfer Stage will ferry the astronauts down to the base in 2033 where they will remain for about 300 days. The astronauts will then return to Earth.

The Orion flight test crew module. Image credit: NASA

The Trip to Mars

Getting astronauts onto the surface of Mars will involve a further six SLS launches. This final part of the mission involves getting a lander in orbit around Mars. The lander will include a Mars Ascend Vehicle that would bring the astronauts to Mars’ surface and then back to earth. The vehicle will be equipped with retrorockets and a drag-increasing Supersonic Inflatable Aerodynamic Decelerator (SIAD) instead of the older parachutes that offer less drag. The lander will support a crew of 2 for 28 days or 4 for 6 days.

Possible Complications

A manned mission to Mars is not an easy feat as there are many things that can go wrong. NASA will rely heavily on the ISS for gathering more information regarding possible health risks of the astronauts and for the testing of equipment. It is necessary to construct Orion in such a way that the astronauts are safe from radiation in interplanetary space, as well as preserving their muscles, bones and internal organs in microgravity for a long period of time. A 300 day stay on Phobos, a moon that has a gravitational pull equivalent to 0.05% of the Earth’s may impact astronaut’s bodies due to loss of muscle mass and bone density. Furthermore, for a trip to such a distant destination, there must be no flaws in any of the launch systems, propulsion systems or space tugs. All systems involved must be tested rigorously before they can be used in order to prevent any complications. Even with the many precautions taken and with rigorous testing, an unmanned mission is necessary prior to the manned missions at each stage in order to minimize the risk of things going wrong.

Humanity has not ventured beyond low-Earth orbit since the Apollo 17 mission. This will be the next big step in space exploration and may be the beginning of humans colonising other planets. Moreover, this will offer the opportunity to study the surfaces of Mars and Phobos further as well as the effects of space travel on human anatomy. If this series of missions is successful, NASA’s scientists hope this will mark the beginning of regular missions to Mars.

Artist concept of NASA’s Space Launch System (SLS) 70-metric-ton configuration launching to space. Image credit: NASA

The Mystery Spots of Ceres

Physics, Space, , , , , ,

by Ioana Boian (edited by Andrew Blance)

How did the Solar System form? How did water originate on Earth? These are some of the questions that researchers studying distant icy objects in the outskirts of our Solar System are trying to answer. By investigating Ceres, a small dwarf planet in the asteroid belt, they hope to shed some light on these mysteries.

Image of Ceres (Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

Ceres arose naturally as a target for observation because of its unique status: it is the largest object in the asteroid belt and the sole dwarf planet in the inner Solar System. Remarkably, it is also known to have an icy mantle and may even have an internal ocean of liquid water. It has even been proposed that under a slightly different set of circumstances Ceres could have evolved into a planet similar to Earth and Mars. Dawn, a spacecraft sent to study dwarf planets, approached this fascinating place in 2015 and sent images home, inspiring further research into the dwarf planet. The images revealed two bright spots on its surface which have proven difficult to explain.

Dawn was launched in 2007. It is not only the first spacecraft to orbit a main belt asteroid but also the first to orbit two extra-terrestrial bodies. The Dawn mission targets both Ceres and Vesta, rocky bodies in the asteroid belt which may hold answers about the early Solar System and its formation. Following the assumptions that Vesta is rocky and Ceres contains large quantities of ice these two bodies provide a bridge between the formation of the inner rocky Solar System and its outer icy parts. Vesta was reached in 2011 and the mission results revealed important new information about its craters and their formation, chemical composition and gravity. The landscape of Vesta was even shown to be surprisingly similar to Mars, or even Earth. Although there are theories that, like Ceres, a pocket of ice exists under the surface, these ideas are still under debate. While a significant amount of data was gathered about Vesta, the more fascinating mysteries involve Dawn’s other target, Ceres.

In 2003 a single shining spot was observed on Ceres by the Hubble Space Telescope, but the discovery was dismissed, believed to be caused by the poor resolution of the image. Later in 2015, Dawn provided more detailed images that proved the spot to be real. It was revealed that the one spot was actually many, and since then several of these groupings of spots have been detected.

Image of Spots Found In Ceres’ Occator Crater. (Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

The main theory proposed by NASA was that sunlight was hitting reflective material found in the crater where the spots were located. The high albedo of the planet pointed towards ice or salt deposits being responsible and since Ceres is known to have an icy mantle, ice was considered to be the likely cause. However, this theory has been recently discredited. Information made available as the Dawn spacecraft continued its orbit towards Ceres has allowed researchers to say with more accuracy what may be causing the reflective patches. Recent proposals suggest these spots are indeed caused by salt deposits. The liquid water hidden inside Ceres would have allowed these salts to grow. Then, when an asteroid collided with the planet, this solution would have been ejected from the planet’s interior and into the crater. Here the water would evaporate away leaving only the reflective salts seen in the Dawn mission images. It is debated however if liquid water still runs under the surface or whether it was only there when the salt formed in the craters tens of millions of years ago.

This is still not the end to this mystery, though! While the spots have been shown to be made from sodium carbonate, it is unknown how such a large amount of the compound could exist on Ceres. Studies recently have suggested that though Ceres has a large amount of underground ice it is not as common as originally thought. Estimates predict that no more than 35% of its substructure can be composed of it. This is a problem as usually this carbonate forms in large bodies of water. Currently the only other place it is found, aside from Earth, has been Enceladus, a moon of Saturn layered in ice. It is a mystery how a planet as small as Ceres could have enough water needed to form this salt. It is hoped that answering this question and understanding the origin of Ceres water supply will allow us to have an insight into how water formed here on Earth. Currently it is suggested that the water in the inner solar system may have originated from the Kuiper Belt, a disc of icy rocks beyond our planets, but exactly how this was transferred to Earth is a mystery. Ceres has the potential to be an intermediate step between the water on Earth and the ice of the Kuiper Belt. Therefore research into Ceres will hopefully allow us to understand the process of how, and if, the Kuiper Belt is responsible for the formation of water on Earth.

Artist’s impression of Dawn spacecraft arriving at the dwarf planet Ceres. (Image credit: NASA/JPL-Caltech)

The Dawn mission has provided a huge amount of information about the dwarf planet Ceres and the asteroid Vesta. Many mysteries regarding Ceres and Vesta have been solved, but there are still many questions left unanswered, predominantly on the nature of Ceres’ water supply. Dawn however is continuously bringing new results, and it is expected to provide answers to this and other long standing questions about the origins of the Solar System. In particular, it is hoped that understanding Ceres will give us insight into how water formed here on Earth and the rest of the inner Solar System, an important and consequential result.

Further Reading:

The most recent images NASA has received of Ceres’ spots:
https://www.nasa.gov/image-feature/jpl/pia21078/occator-on-ceres-limb

Further discussion of what the likely causes of Ceres’ spots are:
http://www.space.com/33302-ceres-bright-spots-new-composition.html
http://gizmodo.com/those-bright-spots-on-ceres-are-weirder-than-we-imagine-1782766156

Nature article regarding levels of underground ice on Ceres
http://www.nature.com/ngeo/journal/v9/n7/abs/ngeo2743.html

Nature article regarding salt formation and water levels on Ceres
http://www.nature.com/nature/journal/v536/n7614/full/nature18290.html

Cloudy, with a chance of solar flares

Solar Physics, Space, ,

by Konstantina Loumou

-Tickets?
-Got them.
-Passport?
-Here.
-What about the weather?
-Checked!

This could be a discussion before a trip to France nowadays… or a  trip to Mars sometime in the future.

Space weather is a branch of astrophysics that studies the Sun and the solar phenomena. Eruptions of different magnitudes are taking place in our star’s atmosphere, feeding the space among the planets with particles. They then travel in space much like a wind, tied to the Sun’s magnetic field, being driven by it and driving it along. Now imagine you’re travelling in space, paying a visit to your friends on a nearby planet. You would probably want to know where those particles are going!

Artist’s impression of the Sun’s magnetic field reconnecting with the Earth’s magnetic field after a solar flare. Credits: ESA

Even though scientists are still searching for the drivers of space weather, they do have a basic picture of what leads to it. The Sun is essentially a large magnet with a magnetic field that resembles the Earth’s. As the field rises from the interior and expands towards the interplanetary space of our solar system, it gets twisted and stretched. This process can cause two magnetic lines of opposite polarities to come in close proximity. According to electromagnetism, if we have a point source in the region of an electromagnetic field being subjected to these conditions, forces can get strong enough to cause the lines to connect, releasing energy at the same time. This energy gets absorbed by particles in interplanetary space which will travel towards the planets and everything in between.

Through this process, it is possible for a storm of space particles to enter the Earth’s atmosphere, changing its density and interacting with the atmospheric particles. This means that the refractive index of radio waves essential for communication with satellites orbiting in the ionosphere is also changing, altering the travel-time of the wave. Aeroplane navigation systems rely upon satellite navigation systems, and a delayed signal from those systems can lead to problems as the plane attempts to land. At the same time, this disturbance of the geomagnetic field can induce additional currents, which themselves can propagate through the electric grid, causing its degradation at a much faster rate than normal. The current induced in electrical transformers can have as a result catastrophic increases in their temperature, which have the potential to lead to a black-out. While this may sound like doom-mongering, it has happened before: in March 1989 Quebec was subjected to a twelve hour-long power-cut, due to a transformer overheating , and in September 2005 a solar flare lead to a complete loss of radio communication in both North and South America. According to the most recent global road map for space weather4, the estimated impact of induced current can lead to damages of $5-10 billion (£4.1-8.2 billion) every year. Insurance companies are increasingly interested in knowing the exact effect of space weather on the technology they manage so that they can adjust their claims accordingly. The same interest is also shared by governments and the military, for whom the long-term running of satellites is vital.

At the same time, a solar storm can pose a health risk for travellers. When an eruption happens, the particles that have absorbed the released energy are free to travel in very high energies. Thankfully, our planet has a magnetic field strong enough to keep an atmosphere that acts as a shield. However,  transatlantic flights tend to fly at high latitudes, thus having a smaller fraction of the atmosphere protecting them from harmful highly energetic particles . In an attempt to mitigate risks, transatlantic trips tend to change their flightpath. Things are worse for the astronauts working on the International Space Station, who have no protection apart from their uniform, and let us not forget your trip to that Martian resort. With the number of manned space missions increasing and Virgin Galactic, a space tourism company, already established, it is crucial to be aware of the occurrence time and direction of any storm which should be avoided.

So, what can we do about it? Solar physicists are developing different techniques in an attempt to forecast those events. However, although large steps have been made, the exact physics governing these events is still unknown. Moreover, the existing observational data and the simulations available don’t agree with each other. Theorists need far more precise data and a lot more information to create a model describing exactly what is happening in the Sun. Therefore, any forecasting method to date, consists of  determining a physical quantity that, according to plasma theory,  might give an indication of an imminent eruption. Its verification can only happen via statistical analysis, which leaves space for uncertainty.

Space Weather has a long way to go, but it is undoubtedly an exciting and promising field, with many more applications in the foreseeable future as humanity continues reaching for the stars.

 

References

  1. Cade, WB; Chan-Park, C. The origin of space weather. Space Weather 13:2:1542
  2. Leighton, RB; Noyes, RW; Simon GW. Velocity fields in the solar atmosphere. I. Preliminary Report. Astrophysical Journal. 135:474
  3. Stix, M. The sun: an introduction. Springer, 2002.
  4. Schrijver, CJ et al. Understanding space weather to shield society: A global road map for 2015-2025 commissioned by COSPAR and ILWS. Advances in Space Research. 55:2745

Glasgow University Researchers Win Sir Arthur Clarke Award

Physics, Space, , , , ,

by Camille Stock

From left to right: Mr Michael Perreur-Lloyd, Dr Ewan Fitzsimons, Dr Harry Ward, Dr David Robertson, Dr Christian Killow (The Glasgow University LISA Pathfinder team)

On the 27th of October this year at the Royal Society in London, the University of Glasgow’s own LISA Pathfinder team was awarded the 2016 Sir Arthur Clarke Award. Sponsored by the UK Space Agency, the Sir Arthur Clarke awards have been acknowledging and rewarding outstanding achievements made in British space activities each year since 2005. This year’s “Space Achievement in Academic Research or Study” award was given to Dr. Harry Ward and his five person team for their involvement on the LISA (Laser Interferometer Space Antenna) Pathfinder. They developed an Optical Bench Interferometer for the ESA spacecraft, and its purpose is to test the practicality of gravitational wave observation in space.

Gravitational waves are a form of radiation that is given off when massive objects are interacting gravitationally. They were predicted by Einstein’s theory of General Relativity, and are normally too weak to be detectable. However, during violent astronomical events such as black hole mergers, the waves are emitted with sufficient intensity and may become detectable by ultra-sensitive instruments. The groundbreaking first detection of gravitational waves (made possible in part by the research done at the University of Glasgow’s Institute for Gravitational Research) was done on 14 September 2015. Following this exciting detection, there has been increased interest in creating even more precise and efficient gravitational wave detectors.

A necessary technology for gravitational wave research is the interferometer, an instrument that bounces lasers off mirrors in a configuration that allows for very precise measurements of the distance between two free-floating heavy masses with reflective surfaces. Interferometers are used in detecting gravitational waves because they are able to measure very small deviations in distance. When a gravitational wave passes by, it stretches and contracts the space it moves through, thereby moving the targets of the lasers. This extremely tiny change in distance gives a different measurement from the original, unperturbed system and indicates the presence of a gravitational wave.

The LISA Pathfinder has been created as a precursor to ESA’s flagship gravitational wave observatory, eLISA, that will hopefully be launched in the early 2030’s. eLISA (Evolved Laser Interferometer Space Antenna) will be a large-scale array of three spacecrafts designed to detect gravitational waves. This array will form a massive triangle configuration orbiting the Sun: it will create an extremely large interferometer, much larger than any interferometer that can be built on Earth. eLISA can be thought of as a huge Michelson Interferometer, with each arm stretching 1 million kilometres! This will allow the measurement of gravitational waves to take place over a broad band of low frequencies (0.1mHz to 1Hz). This is a much richer range than is possible on Earth at observatories such as LIGO (Laser Interferometer Gravitational Wave Observatory), due to terrestrial gravity gradient noise and arm-length limitations.

LISA Pathfinder in space. (Image credit: ESA/C. Carreau)

In order to make eLISA happen, LISA Pathfinder has been created to test how certain technologies necessary to gravitational research hold up in space. The Optical Bench Interferometer realised by the team in the School of Physics and Astronomy helps test the practicality of flying a gravitational wave observatory in space, and carrying out experiments in these conditions. Unperturbed by any external forces, being in space creates an extremely quiet environment to conduct these measurements, allowing scientists to measure the effects of gravity with great accuracy.

So far, the first results indicate LISA Pathfinder has been working to a precision five times better than required. This is great news and helps give a green light for the eLISA mission to progress. The success of LISA Pathfinder is due to many people’s research, but notably, the work done here at the University of Glasgow in the Institute for Gravitational Research.

Bibliography:
More information on the Sir Arthur Clarke Awards: http://www.bis-space.com/2016/10/24/17965/the-sir-arthur-clarke-awards-2016
More information on Dr. Harry Ward and his team at the University of Glasgow:
http://www.physics.gla.ac.uk/igr/index.php?L1=research&L2=lisa
More information on LISA Pathfinder and eLISA:
https://www.elisascience.org/

Is it better to walk or run in the rain?

Physics, , , ,

by Paul Räcke

It rains a lot in Glasgow. How often have you left the Kelvin building thinking to yourself that you should have brought that rain jacket of yours today or should have bought that umbrella the other day? In these moments it is probably better to stop thinking about things that can no longer be changed and start thinking about what to do next! During such a time many people wonder if it is better to run as fast as possible in the rain to escape getting wet or to walk instead, as you are going to get wet anyways? Wouldn’t you get wetter if you are hit by the rain on the face? On the other hand, if you walk slowly, you end up spending more time in the rain and thus get much wetter. So what is the right course of action one can take in this dire situation?

In principle, there must be a logical approach to work this out. This is what theoretical physicist and YouTuber Henry Reich thought and to finally settle this issue, he made a video helping us through this dilemma on his channel MinutePhysics.

It is sensible to start with a few approximations to make calculations as easy as possible: “Assuming you are not fully soaked yet and you are not jumping into puddles, the answer is simple”, Reich states in his introduction to the problem. He assumes that the rain falls completely vertically with respect to the planar ground, without any wind or other effects. Furthermore, he imagines that the concerned person (let’s say that is you) is a rectangular cuboid.

The area of a parallelogram (and equally the volume of a parallelopided) represents the amount of rain hitting you from above during a given time. It does not depend on the slant, i.e. the speed you are going. From YouTube video “Is it better to walk or run in the rain?”.

There are two contributions to your overall wetness: rain from above and rain from the side. First consider the rain from above (i.e. the rain falling right on your head), which will be constant no matter how fast you are going. This might or might not be intuitive, but it becomes perfectly clear with Reich’s clever way of visualising the mathematics behind it. Consider the raindrops stationary in space and yourself (in fact the cuboid that represents you at the moment) and the ground moving upwards. The slant of the parallelepiped that encloses all raindrops that hit your top surface depends on your speed, but the volume of the rain, i.e. the amount of rain, does not change. This can be seen in the picture, where the problem is already reduced to two dimensions, due to the symmetry in the third dimension. So, you get a constant amount of rain from above plus an amount of rain from the side that increases with your velocity component parallel to the ground. Solving this equation leads to the odd result that you should stay at the same point and not move at all to minimise wetness. That cannot be right. And it isn’t. It is provable with parallelepipeds again, that the amount of rain hitting you from the side while going from point A to B does not depend on the speed, but only on the distance.

So, in conclusion, the correct equation gives the total wetness after going from A to B as:

Total wetness = wetness per s (from top) x time in s + wetness per m (from side) x distance in m.

The second part in the sum is of course constant if you want to get from A to B, while the first part depends on the time you need. So run! Be careful and don’t hurt yourself or others. But run as fast as you can!

Henry Reich explains in an interview with Brady Haran (another very engaged YouTuber with many channels on sciences and mathematics, etc.), that the idea of drawing stick figures and simplified objects to explore and solve physics problems was born during his master’s when he was trying to explain his research on general relativity to undergraduate students. This concept ended up being so popular and effective that he now produces YouTube videos full-time and has started a second channel called MinuteEarth where he discusses ecology, ecosystems and the interactions between humans and their home planet.

Other enlightening videos from MinutePhysics include the answers to questions like “How to see without glasses?”, “Is there poop on the moon?” or “What is sea level?” as well as considerations about the Higgs Boson, our expanding universe and the mysteries of quantum mechanics.

Be sure to check out Reich’s videos as well as the many more YouTube channels that bring together science education and entertainment in brilliant ways for a wide audience and specialists alike, such as: Physics Girl, SciShow, thebrainscoop, Veritasium, Vsauce, SmarterEveryDay.