The New Space Projects - National Geographic
The space programmes on the verge of game-changing discoveries. By Mark Bailey
PHOTOGRAPH BY NASA, JPL CAL-TECH
1. THE MISSION TO TOUCH THE SUN
“The Parker Solar Probe will be the first to literally fly through the corona (outer atmosphere) of the Sun,” explains Professor Brad Gibson, Director of the E.A. Milne Centre for Astrophysics at the University of Hull. In this halo of plasma (hot ionised gas), temperatures reach 2 million degrees Kelvin (1,999,727 degrees Celsius). “We have studied the sun from 90 million miles away, and satellites have taken some spectacular images, but this is the closest we have got. It will travel within 4 million miles of the sun, which sounds quite far but is actually 10 times closer than Mercury - the nearest planet to the Sun.” The satellite launched in August 2018 and will make 24 orbits in seven years. “We will learn about the origins and frequency of coronal mass ejections (CME) and solar flares, which can knock out electrical grids here on Earth and damage satellites.” Solar flares are explosive eruptions of light, whereas CMEs blast hot plasma into space. “The Parker probe will get close enough to actually touch the materials involved.”
2. THE UNMASKING OF MERCURY
“Mercury remains relatively unexplored and it has a pretty harsh environment (its surface temperature can reach 450 degrees Celsius) but as this is the closest planet to the sun the BepiColombo mission there will give us unique insights into the inner region of the solar system,” explains Gibson.
The joint European Space Agency (ESA) and Japan Aerospace Exploration Agency (JAXA) mission launched on October 20, 2018, and will reach Mercury by 2025. It will transport the planet-mapping Mercury Planetary Orbiter (MPO) and the magnetic-field analysing Mercury Magnetospheric Orbiter (MMO).
“Mercury is a relatively pristine environment so we will get amazing insights into the chemical imprint at the very beginnings of our solar system. Unlike Venus and Mars, it also has a magnetic field we want to study because we think they could be pivotal in the development of life, helping to shield complex molecules from high-energy radiation so they don’t get blasted apart before life has chance to develop.”
3. SEARCHING FOR THE WATER OF LIFE
“Mars and Europa have exciting potential in our search for water,” says Gibson. “Water is likely to be a fundamental building block for life: if you are a tiny cell, water can dissolve anything to help you extract energy and it is also a great medium to extract waste.” In July 2018 the Marsis radar instrument on ESA’s Mars Express orbiter found a lake beneath the surface of Mars.
“We don’t know if it’s a lake or just muddy goo but it’s an exciting place to search for life.”
Meanwhile, NASA’s Europa Clipper, which will launch in 2022-2025, aims to explore the subsurface ocean on Europa – an ice-encrusted moon orbiting Jupiter. “Ice freezes from the top so during any wild climactic changes on a water-rich planet the ice provides a protective coating for nascent life beneath. The Europa Clipper will scoop up that water and help us search for bacterial life.”
4. THE EXOPLANET HUNTER
NASA’s Transiting Exoplanet Survey Satellite (TESS) launched in April 2018 to hunt exoplanets (planets located outside our own Solar System) which could change our understanding of Earth. “This is a hugely ambitious project that could discover Earth-like clones,” says Gibson. “Based on the 4,000-5,000 exoplanets we currently know about, our solar system looks weird, with low-mass planets at relatively far-away distances from the Sun and no super-Earths (planets 1-10 times the mass of Earth). That contributes to the Rare Earth hypothesis that we may be unique. However, we don’t know if that is true, or just because we don’t have enough exoplanet data for comparison. TESS will change that by revealing ten times the number of exoplanets so we will finally know if we’re unique.”
TESS will also help identify which exoplanets the James Webb Space Telescope (the successor to the Hubble) should target for more detailed examination following its launch in 2021.
5. SHOOTING FOR NEW MOONS
Astronomers David Kipping and Alex Teachey of Columbia University believe they have discovered the first exomoon (a moon outside our Solar System), using data from Nasa’s Kepler spacecraft and the Hubble telescope. This opens up a new frontier in the search for life.
“Moons are important for life because of their stabilising influence on the tilt of a planet’s orbit around its host star,” explains Gibson. “Our own heavy moon keeps the Earth tilted at 23 degrees away from the sun which means we enjoy stable seasons. Without the moon, the Earth would tilt all over the place and face wild climactic shifts. Our moon is 1/100th the mass of the Earth whereas most moons in our solar system are 1/100,000th the mass of their host planet. That stability supports the development of life, so discovering an exomoon outside our Solar System is especially exciting.”
6. THE HUNT FOR ASTEROID SAMPLES
“Sample-return missions to asteroids will provide incredibly important information about the origins of our solar system,” explains Gibson.
The Japanese Hayabusa2 mission landed rovers on Ryugu, a 1km-wide asteroid around 180 million miles from Earth, in September2018 and will return with samples in December 2020.
“Carbon-rich asteroids like Ryugu carry chemical fingerprints from the formation of the solar system. Carbon is a likely building block for life because of its role in making complex organic molecules. Everything organic involves carbon. Those rovers will also collect samples, from rock and ice to early-stage organic compounds, which will reveal any role asteroids might have played in delivering water and the chemical building blocks of life to distant planets.”
The NASA mission OSIRIS-REx reached the 492m-wide asteroid Bennu this month [December 2018] and will return to Earth in 2023 with up to 2,000g of rock and dirt.
“That’s a huge chunk of material for astrophysicists and geologists to dig into.”
7. SIMULATING THE COSMOS
“The Horizon Run is the most ambitious cosmological simulation to date,” explains Gibson.
A collaboration between his own University of Hull and the Korea Institute for Advanced Study, this simulation will run at over 100 million core hours (that’s the number of processor units – or ‘cores’ - used to run the simulation multiplied by the duration of the job in hours).
“It uses high-performance super-computers and sophisticated software to generate incredibly accurate realisations of what the universe looks like.”
The project is 10 times larger than the pioneering galaxy-simulating Illustris and EAGLE simulations, the latter of which tracked 7 billion simulated particles over hundreds of millions of years. “Instead of exploring a subset of the universe and extrapolating out from that we are doing the whole volume. But we can also data-mine millions of other galaxies, to deconstruct them and perform chemical tagging, so we can really advance our understanding of the universe.”
8. MAPPING THE MILKY WAY
“ESA’s Gaia satellite is giving us the power to re-construct with exquisite precision the six-dimensional structure of the Milky Way,” says Gibson.
The Milky Way is the galaxy that contains our own Solar System.
“This kind of galactic archaeology is giving us a renaissance in our understanding of the Milky Way. We are starting to build an accurate map of all the billions of stars in the galaxy, but also monitoring which directions they are moving in – giving an x, y and z grid position but also their velocity in x, y and z directions. And if you know the age of the star, that gives you a seventh dimension to play with. With this map we can ultimately start to wind the clock forwards or backwards to understand how the Milky Way formed and what its future is.”
9. THE QUEST FOR DARK MATTER
Dark matter – the ubiquitous particles which are believed to account for 85% of the matter in the universe, and hold the galaxy together - remains a hypothetical mystery. But the Axion Dark Matter Experiment (ADME) at the University of Washington hopes to change that.
“We know dark matter is there because we can feel its gravitational influence,” says Gibson. “There is this enormous dark matter spread throughout the galaxy which we can’t see. So the search for it is about eliminating possible candidates one by one. Right now, axions - theoretical subatomic particles which could be a component of dark matter - are interesting candidates.”
ADME uses a resonant microwave cavity and a superconducting magnet to cycle through frequencies in an attempt to detect any signals which might betray the presence of axions. "We should know within 5-10 years whether they are the secret to dark matter or just a distraction.”
10. PHOTOGRAPHING A BLACK HOLE
“The Event Horizon Telescope (EHT) is on the verge of taking a ‘picture’ of a black hole,” explains Gibson.
Black holes are regions of space where gravitational forces are so strong than nothing – not even light – can escape. And because no light can get out, they remain invisible. “We only know black holes exist because we can see their gravitational effects on the surrounding environment,” continues Gibson.
“The EHT is now using a dozen telescopes spread across the Earth to create an ‘Earth-sized telescope’ that will photograph the actual shadow of a black hole instead.”
This will capture the ‘event horizon’ – the boundary of the black hole – which should be backlit by gas. The primary target is Sagittarius A* - the supermassive black hole at the centre of our galaxy.
“The event horizon is 1,000 times smaller than anything you could see with the Hubble Space Telescope but the EHT has 3,000 times better resolution. It could happen tomorrow or next month but it’s coming.”
(C) National Geographic
Link: https://www.nationalgeographic.co.uk/space/2018/12/discover-the-10-most-exciting-space-projects-right-now