It is always reassuring to catch that first familiar glimpse of home after a great adventure, but for our space-faring satellites the return visit is brief and of a practical nature: to use the planet’s immense gravity to sling it onto a new trajectory.
These ‘gravity assists’ are fleeting encounters, but enough to change the spacecraft’s speed and direction such that it can eventually enter orbit around another world.
This delicate view of Earth was captured in 2007 on the second of three Earth flybys made by ESA’s comet-chasing Rosetta spacecraft on its ten year journey to Comet 67P/Churyumov-Gerasimenko. The spacecraft also got a boost from Mars to set it on course with its destination.
The first ever interplanetary gravity slingshot took place on 5 February 1974, when NASA’s Mariner 10 flew past Venus en route to flybys of Mercury. The ESA-JAXA BepiColombo mission – whose name is inherited from Giuseppe Colombo who originally proposed to NASA the interplanetary trajectories that would allow Mariner-10 multiple Mercury flybys by using gravity assists at Venus – will make nine flybys of Earth, Venus and Mercury to reach the innermost planet and eventually enter orbit about it.
Similarly, ESA’s upcoming Solar Orbiter mission will use Venus gravity assists to change its inclination to get a better look at the Sun’s poles. And ESA’s Jupiter Icy Moons Explorer will first dive into the inner Solar System to use Earth, Venus and Mars to set course for the gas giant Jupiter.
But Earth remains home to a fleet of satellites busy performing a number of different activities from orbit: while some are peering far away into the cosmos, our Earth Observation missions are watching diligently over our precious planet, taking its ‘pulse’ and helping us to better understand how to care for it. The Sun-illuminated crescent seen around Antarctica in this beautiful image certainly evokes a feeling of fragility and reminds us of our special place in space.
The image was taken by the OSIRIS camera on Rosetta about two hours before closest approach during the 13 November 2007 flyby, when the spacecraft was 75 000 km from Earth. The mission went on to become the first to rendezvous with and land on a comet, and the first to follow and study a comet on its orbit around the Sun.
“Valentine’s Day has struck again,” tweeted ESA astronaut Thomas Pesquet when he posted this image of a heart-shaped lake in Mongolia. Thomas took this image from the International Space Station during his Proxima mission in 2017.
Two years on, it is that time of year again, the day that brings some joy and others anxiety. But if thoughts of ordering flowers and making dinner reservations are stressing you out, spare a thought for our stressed-out Earth.
The fact that Earth is rich in flora and fauna is without question, but our planet is changing fast – particularly because human activity is placing pressure on natural resources.
Increasing industrial production and a continued reliance on fossil fuels is causing global temperatures to rise. With a change in climate comes huge environmental challenges that humans will not be able to keep up with.
We need to check the status of our relationship with Earth before we wreck it. How?
The first step to fixing a problem is to understand the causes and full extent of it. The vantage point of space provides a window on the world like no other, through which to understand and monitor our changing planet.
And Earth-observing satellites are not the only tools to do this. Astronauts are also viewing Earth from space and taking pictures. Their photography is not just a perk of being an astronaut; they are often used to supplement satellite imagery and provide a different perspective.
Take the case of ESA astronaut Andreas Mogensen. He was tasked with capturing a phenomenon notoriously difficult to photograph from Earth: elusive electrical discharges in the upper atmosphere that sport names such as red sprites, blue jets, pixies and elves. Reported by pilots, they are difficult to study as they occur above thunderstorms. (A dedicated instrument called ASIM has since been launched to the Space Station to monitor this phenomenon).
Besides their value to science, astronaut photographs from space are a great tool for science communication. From the very first images of Earth taken by NASA astronauts in the 1960s that showed the world how fragile Earth is, to the ones like this taken by astronauts and posted to social media, they all drive home an important message:
Love our planet, because it is the only home we have.
Copernicus Sentinel-2 brings you some of the jewels of the Maldives for Valentine’s week. Arguably one of the most romantic destinations in the world, the Maldives lie in the Indian Ocean about 700 km southwest of Sri Lanka. The nation is made up of more than 1000 coral islands spread across more than 20 ring-shaped atolls.
A number of these little islands can be seen in the image, with the turquoise colours depicting clear shallow waters dotted by coral reefs and the red colours highlighting vegetation on land. Different cloud formations can also be seen, the difference in appearance is likely to be due to the different height above the surface.
Like many low-lying islands, the Maldives are particularly vulnerable to sea-level rise. In fact, the Maldives are reported to be the flattest country on Earth, with no ground higher than 3 m and 80% of the land lying below 1 m. With satellite records showing that over the past five years, the global ocean has risen, on average, 4.8 mm a year, rising seas are a real threat to these island jewels.
With the promise of white sandy beaches, azure ocean waters and coral reefs, this romantic getaway draws more than 600 000 tourists every year. While tourism is extremely important for the national economy, development on these pristine islands create pressures, such as ensuring an adequate supply of freshwater, treating sewage and potential pollution entering the ocean. Other environmental issues facing the Maldives include the loss of habitats of endangered species and the damage to the coral reefs.
The Maldives are undoubtedly fragile but one of the most beautiful places on the planet, and a place to be loved and cherished now and in the future. Valentine’s Day reminds us of love and maybe this year and beyond it’s good to remember to love our planet.
This image, which was captured on 26 August 2015, is also featured on the Earth from Space video programme.
ESA and the Italian Space Agency (ASI) officially launched the European Space Education Resource Office (ESERO) in Italy on 14 February 2019. The project will be led by ANISN, the National Association of Natural Sciences Teachers. The contract was signed by ESA's Chief Strategy Officer Kai-Uwe Schrogl and the president of the Italian National Association of Natural Sciences Teachers (ANISN) Anna Pascucci.
ESA astronaut Alexander Gerst returned to Star City, Moscow, this week where he attended a traditional welcome home ceremony alongside NASA astronaut Serena Auñón-Chancellor and Russian cosmonaut Sergei Prokopyev at the Yuri Gagarin Training Center (GCTC).
Held on Tuesday 12 February, almost two months after the trio’s return from the International Space Station on 20 December 2018, the ceremony saw Alexander, Sergei and Serena lay flowers at the monument of Soviet cosmonaut Yuri Gagarin and receive gifts from friends and colleagues in Russia.
It was the first time such a ceremony had been attended by two ambassadors from partner countries. German ambassador Russia Rüdiger von Fritsch and American ambassador Jon Huntsman Jr were both in attendance.
The crew was also greeted by Roscosmos deputy director for human spaceflight Boris Shishkov, GCTC head of center Pavel Vlasov, his first deputy cosmonaut Yuri Malenchenko, newly-elected director general of RSC Energia Nikolai Sevastyanov and officials from regional government.
As the crew of Expedition 56/57, Alexander, Sergei and Serena spent 197 days in space.
Evaluation of a test Hiber nanosatellite took place in ESA’s metal-walled Hybrid European Radio Frequency and Antenna Test Zone (Hertz) at the Agency’s technical centre in the Netherlands, shut off from all external influences and the walls clad in signal-absorbent foam for radio testing.
One of the NASA/ESA Hubble Space Telescope’s many scientific objectives is to study the planets within the Solar System — and in past years, our system’s outer planets have been observed several times as part of Hubble’s Outer Planet Atmosphere Legacy (OPAL) programme.
This programme has given us this new image of the planet Uranus, the seventh planet in the Solar System in order of increasing distance from the Sun. Past observations of Uranus using Hubble have led to many interesting insights about the cold ice giant; in 2006 the telescope managed to capture a shot in which the moon Ariel and its accompanying shadow were traversing the face of Uranus, and in 2011 Hubble was able to spot faint auroras in its atmosphere.
Observations made over the course of several years also allowed astronomers to study the planet’s faint ring system as its inclination changed with respect to Earth’s orbit. This new image, taken with Hubble’s Wide Field Camera 3, adds to the legacy of images already taken and will provide scientists with even more new insights into our distant neighbour.
Week in images
11 - 15 February 2019