TRAPPIST-1: Could This Newfound Star System Hold Alien Life?

Josh Bason

On February 20th 2017, NASA announced a press conference to discuss a “discovery beyond our solar system”. Two days later they revealed the TRAPPIST-1 system; a series of seven earth-size planets orbiting a star 39 light years from Earth. The announcement of this discovery and the discussion that followed has circled one tantalising question – could the TRAPPIST-1 star system harbour extraterrestrial life?

The scientists at NASA certainly seem excited about the concept. Their search for exoplanets – that is, planets orbiting stars other than our own sun – had until this point yielded only a handful of potentially habitable worlds. Among TRAPPIST-1’s seven planets, however, no less than three have shown this potential, setting a record for the most known earth-like planets orbiting one star.

These worlds were highlighted by the scientists primarily for their location in the so-called ‘habitable zone’. This describes the range of orbit sizes where, dependent on the size of the planets and the star, it is neither too hot nor too cold for life to sustain life.

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Artists impression of the surface of TRAPPIST-1f, the fifth planet in the TRAPPIST-1 system Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle

Further investigations by NASA scientists have also yielded promising results. Using precise measurements of the size and mass of the planets, the researchers were able to calculate estimates for the density of each of TRAPPIST-1’s worlds. These density measurements are key to understanding exoplanets as they give us our first insight into their composition.

Of the seven planets in the newly-discovered system, six have been described as ‘rocky’ – that is, more comparable solid planets like Earth and Mars than gas giants like Jupiter and Saturn. The seventh planet, which has the widest orbit and an undetermined mass, has been provisionally described as ‘snowball-like’.

Despite these hopeful indications, there is also a body of evidence which is significantly less inspiring. Firstly, while it’s tempting to imagine TRAPPIST-1 as a distant copy of our own solar system, the absence of two planets is not where the dissimilarities end. The most striking difference between this newly-discovered system and our own is the star which lies at the centre.

The star is classified as an “ultra-cool dwarf”, meaning it is both ten times smaller than our sun and less than half its temperature. While this doesn’t sound like a recipe for warm earth-like planets, the small size of the star is counteracted by the proximity of the planets which orbit it.

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NASA’s illustration of the size of TRAPPIST-1. (Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle)

The seven worlds of the TRAPPIST-1 system all orbit between one and five million miles from their star. This means that all seven planets could fit comfortably in the space between the sun and Mercury, with its 58-million-mile orbital distance. While the size of the TRAPPIST-1 system isn’t necessarily a barrier to the formation of life, it certainly represents a significant divergence from the only solar system where we’ve ever observed it.

It’s also important to bear in mind how little is known about the planets of the TRAPPIST-1 system. Despite the array of concept images released by NASA in the wake of the announcement we don’t, in fact, have any idea what the planets look like. The planets were found, or more accurately their existence was inferred, by observing the light emitted by the star they orbit.

This process, known as transit photometry, involved watching the star’s brightness over time and finding dips in luminescence when planets passed in front of it. From this information, NASA scientists extrapolated a range of information, such as their size, mass and orbital distance. What this technique doesn’t reveal, however, are other key factors that determine the habitability of a planet.

Because of this, we still do not know whether any of the TRAPPIST-1 planets contain atmospheres, which are vital for life, or magnetic fields, which can protect life from deadly solar wind. NASA are also not discounting the possibility that some or all the planets may be ‘tidally locked’, meaning that one side may permanently face the sun with the other half perpetually facing away. Conventional wisdom suggests life would be impossible on such a planet, as one half would be too hot for life and the other too cold. More recent evidence, however, has suggested otherwise.

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NASA’s idyllic concept art is based almost entirely on speculation. (Credit: NASA/JPL-Caltech/R. Hurt, T. Pyle)

Furthermore, since the announcement of the NASA’s discovery, two pieces of research have poured cold water on hopes of life in the TRAPPIST-1 system. The first, published on March 30th, detected frequent flares emitted from the system’s star. Considering the small orbital distances of the nearby planets the authors feared that these huge releases of energy may disrupt the atmospheres of the planets and that without the protection of strong magnetic fields, life in the system may be impossible.

If that wasn’t disheartening enough, research published on April 6th revealed a new climate model to assess the habitability of exoplanets. The study concluded that only one of the planets, TRAPPIST-1e, was likely to support liquid water. If this planet does not possess a substantial enough magnetic field to weather the flares from its nearby star (something scientists feel is unlikely), all hope for life in TRAPPIST-1 may be lost.

Despite this disappointing news, research into TRAPPIST-1 continues. NASA has announced plans to use its new James Webb Space Telescope, launching in 2018, to search for key atmospheric components such as oxygen and water in the system.

The increased sensitivity of the Webb telescope will also allow the surface temperature and pressure of the planets to be measured, answering yet more questions about the habitability of the system. Until then, however, the hospitability of the TRAPPIST-1 system remains very much in question.

Male Contraceptive Injection Shows Promise

Josh Bason

Since it was first introduced in 1961, the contraceptive pill has provided an effective family planning solution for millions of couples across the world. Yet to this day, a similar hormonal solution for male contraception has been elusive. A recent clinical trial, however, seems to move us much closer to a breakthrough.

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Image Credit: Flickr

The trial tested a pair of hormonal injections, given every eight weeks, which were designed to lower the sperm count of the participants by temporarily preventing their production of sperm cells. The injections were very effective at preventing pregnancies; among the female partners of the 266 men tested only 4 pregnancies occurred. This shows a success rate of 98.4%, which is comparable with many of the pills currently available for women.

Side effects in studies like this one are common and many participants reported adverse side effects from the jabs. The men most commonly complained of acne, libido changes, and emotional disorders, with 20 of the participants dropping out of the study because of these effects.

During the course of the trials, the researchers had to run their results past two ethics committees to ensure the side effects weren’t so significant that the study should be stopped. While the first of these review boards gave the researchers the all clear to continue, the second panel looked at the same data and ruled that the trial should be halted immediately, citing concerns about mood changes, depression and increased libido.

While it’s difficult to know exactly why the decision was taken to stop the trial, it is reassuring to know that this does not signal the end of research into male contraception. When asked, over 75% of the study’s participants said they were satisfied with the injections as a method of contraception and would be happy to use them if they were commercially available. The study’s authors, too, are optimistic about the future of the method, telling the BBC they are working on combining different levels of the hormones, as well as different ways of delivering them, such as gels.

It’s still difficult to believe that the development of a male contraceptive pill has taken so long. Such pill would alleviate the burden of birth control from women and bring more equality to the realm of family planning. While social factors no doubt play into this continuing inequality, there are simpler biological factors at play too.

The basic mechanism of all contraception is preventing sperm from meeting egg in the uterus. It’s convenient, therefore, that there exists a state in which egg release stops completely: pregnancy. Female contraceptives work by mimicking the hormonal environment of pregnancy, preventing any egg release from the ovaries. Sadly, there are no such natural breaks in sperm production – from its beginnings during puberty, production of the cells continues until death, at the startling rate of 1,000 sperm per second.

It is therefore a significant medical achievement to have reversibly prevented sperm production in the way that this study shows. The challenge now will be to limit the side effects of the treatment and, perhaps more importantly, to find a more cost effective and practical method of delivering it to patients.

Feeling Spaced Out: The Body in Orbit

Josh Bason

On November 2nd 2000 the first crew arrived at the fledgling International Space Station. In doing so they began a 16-year human presence in Earth orbit which continues to this day. While this is a massive achievement for humanity, we shouldn’t be fooled into thinking that the many difficulties of long-term human space travel have been overcome. Space is an incredibly hostile environment and has a long list of detrimental effects on the body, ranging from the inconvenient to the potentially deadly.  

This first of effect of space travel is hard to miss. Take a look at the photo on the left showing British astronaut Tim Peake in orbit on the International Space Station (ISS). Then compare it to the photo on the right showing him down on Earth just days earlier. Obviously, his face looks much rounder and more swollen on the left, and this isn’t unusual in astronauts.

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Tim Peake on the International Space Station (left) and a few days earlier on Earth (right)

Image Credit: Wikimedia

When a human reaches orbit and feels microgravity (NASA’s technical term for weightlessness) for the first time, the fluids that fill their bodies change their distribution dramatically. These fluids, no longer held down by gravity, rush into the upper body causing facial swelling, bulging veins and congestion of the sinuses.

The effect of this change is like a bad head cold; it’s uncomfortable and messes with the astronaut’s senses of taste and smell. While no one loses sleep over an astronaut temporarily losing their sense of smell, the dulling of taste can provide a challenge to chefs preparing food to be eaten in orbit. To compensate, cooks make space food extra spicy, so astronauts don’t have to suffer bland food for their six month stays on the ISS.

Space sickness (or Space Adaptation Syndrome) is another side-effect of orbital travel that’s hard to ignore – for the astronauts at least. As their vestibular system (the fluids in their inner ear which tell them which way is up) struggles to adjust to a world where ‘up’ and ‘down’ don’t mean much, around 50% of astronauts experience nausea and disorientation.

The symptoms of space sickness don’t last too long though – after a couple of days in orbit the symptoms of space sickness subside as the vestibular system of the space traveller adjusts to its new surroundings. Unfortunately, for many astronauts (including Britain’s own Tim Peake) space sickness returns with a vengeance when they land back on Earth – their vestibular system has adapted to weightlessness so completely that the return of regular gravity is dizzying.

The weightlessness of Earth orbit also has some more serious effects on the human body. When an astronaut spends time in space, they begin to lose huge amounts of mass from their muscles and bones. The reason behind both is simple: use it or lose it.

When standing on Earth our legs and spines are constantly working to keep us upright. With no weight to support in orbit, the body starts to break down these bones, washing their vital calcium content away in the bloodstream. This leads to bone loss of up to 1% for every month spent in space.

Muscle loss in microgravity can be even more dramatic, with up to 20% loss from just one week in orbit – especially from the so-called ‘antigravity muscles’ of the legs and back which keep us upright here on Earth.

Needless to say, this is a huge problem for astronauts. Not only do they need their bones and muscles for strenuous activities in space, studies have shown that while muscle mass recovers relatively quickly back on Earth, bone density never completely returns to normal.

To try to combat this, the ISS is equipped with an artificial gravity treadmill, in which astronauts are pulled onto a running surface by straps. This not only gets their muscles working but puts their bones under compression, encouraging them to retain their precious calcium.

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Astronaut Frank De Winne working out on the same artificial gravity treadmill where Tim Peake famously ran the London Marathon in space

Image Credit: Wikimedia

Another substantial problem for space travellers is the impact weightless has on their eyesight. 80% of astronauts are thought to suffer from Visual Impairment Intracranial Pressure syndrome, a condition caused by space travel which does huge damage to the eyes.

Brain scans of returning astronauts show eyes that have been compressed top-to-bottom, pushing the retina backwards into the brain. NASA scientists believe this is caused by the increased pressure in the skull when bodily fluids shift upwards in microgravity. As yet, this worrying syndrome remains unsolved and untreated.

Finally, not all problems in space emerge from the absence of gravity. Also missing in space is the protective layer of atmosphere that surrounds the Earth. Along with providing us air to breathe, our atmosphere also shields us from cosmic rays – dangerous radiation from beyond the solar system that pummels our planet day and night. During cosmic events called solar storms the Sun throws out radiation too, adding to the barrage of incoming rays.

Out in space, astronauts aren’t protected from any of this radiation; despite significant shielding on the walls of the ISS, projections have shown that astronauts living there could reach their lifetime safe limits for exposure in just 18 months. This is bad news for those planning missions to Mars, as even a brief trip to Mars would take over a year.

Scientists must find shielding methods that are both light enough to take to Mars and strong enough to keep astronauts safe, even during solar storms, or risk causing them serious health problems – mainly in the form of cancers – years down the line.

So there’s still a long way to go until long-term interplanetary trips are feasible for the fragile human body; space remains a dangerous and taxing environment for the people who travel there. Nonetheless, scientists across the world are working to change this, and we at pH7 wish them the best of luck.

Antibody Treatment Offers Alzheimer’s Advance

Josh Bason

So, another week and another Alzheimer’s breakthrough is gracing the headlines of the papers. The research in question was issued in Nature last week with the title of “The antibody aducanumab reduces Aβ plaques in Alzheimer’s disease”. The paper, a formal write-up of lab work and clinical trials, describes startling results of a new drug designed to destroy the characteristic brain structures seen in the disease.

Needless to say the drug was successful – so successful in fact that the decline in brain function in actual Alzheimer’s patients was measurably slowed after a year on the drug. Not only is the prospect of a new drug to treat Alzheimer’s an exciting and important one, this research also holds significant promise for developing and extending our understanding of the disease.

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Image Credit: Flickr

To understand what aducanumab does and how, you’ll need a bit of background on what a brain affected by Alzheimer’s looks like down the microscope – what researchers call the ‘neuropathology’ of the disease. Two unusual structures can be seen throughout an Alzheimer’s brain; tangles of protein inside neurons, and dense plaques in the spaces in between.

It’s long been theorised that the formation of plaques was the root cause of Alzheimer’s symptoms, while the tangles were just a by-product of the damage they caused. This idea, known as the ‘amyloid hypothesis’ (after beta-amyloid, the protein which makes up the plaques) has been fundamental to our understanding of Alzheimer’s for over ten years. During this time endless attempts have been made to treat the disease using drugs that target the beta-amyloid plaques. These attempts have been largely unsuccessful – until aducanumab.

Aducanumab is an antibody – it can target specific shapes on the surface of a beta amyloid plaque in the same way your immune system recognises bacteria. The antibodies in the new drug bind to the surface of the plaque and engage the immune system to clear the plaques from the brain. When the researchers demonstrated how well this worked using genetically modified mice, they started trials on humans.

The clinical trials, carried out with 125 early-stage Alzheimer’s patients over one year, showed results similar to the results seen in the mice; there was a reduction in the number of beta amyloid plaques in the patient’s brains. What’s even more exciting than that is the news that across several tests of cognitive impairment the patients who were treated with the drug showed a slowing of the mental decline normally seen in disease patients. While this seems hugely encouraging for aducanumab, the authors of the study make it very clear that we shouldn’t get too excited – their sample size of patients was too small to say for sure whether the drug is actually effective in slowing Alzheimer’s disease, this is merely an indication that aducanumab is worth further investigation.

While we shouldn’t take these reports of slowed decline as evidence that a new Alzheimer’s treatment is around the corner, this research is still hugely important. The work establishes a link between the destruction of beta-amyloid plaques and a change in the symptoms of Alzheimer’s patients for the first time. This lends credence to the idea that the key to treating Alzheimer’s patients lies in the removal of beta-amyloid plaques, just as the amyloid hypothesis suggested so long ago.