Tag archives: asteroids
NASA image of the star field in the constellation Ophiucus; at the centre is the recurrent Nova RS Ophiuci (Credit: John Chumack)
By Tushna Commissariat
Complex organic compounds – one of the main markers of carbon-based life forms – have always been thought to arise from living organisms. But new research by physicists in Hong Kong, published yesterday in the journal Nature, suggests that these compounds can be synthesized in space even when no life forms are present.
Sun Kwok and Yong Zhang at the University of Hong Kong claim that a particular organic compound that is found throughout the universe contains complex compounds that resemble coal and petroleum – which have long been thought to come only from carbonaceous living matter.
The researchers say that the organic substance contains a mixture of aromatic (ring-like) and aliphatic (chain-like) complex components. They have come to this conclusion after looking at strange infrared emissions detected in stars, interstellar space and galaxies that are commonly known as unidentified infrared emissions (UIEs). These UIE signatures are thought to arise from simple organic molecules made of carbon and hydrogen atoms – polycyclic aromatic hydrocarbon (PAH) molecules – being “pumped” by far-ultraviolet photons. But Kwok and Zhang both felt that hypothesis did not fill the bill accurately enough, when they considered the observational data.
As a solution, they have suggested an alternative – that the substances generating these infrared emissions have chemical structures that are much more complex. After analysing the spectra of star dust forming when stars explode, they found that stars are capable of making these complex organic compounds on extremely short timescales of weeks and that they then eject it into the general interstellar space – the region between stars.
Kwok had suggested, at an earlier date, that old stars could be “molecular factories” capable of producing organic compounds. “Our work has shown that stars have no problem making complex organic compounds under near-vacuum conditions,” says Kwok. “Theoretically, this is impossible, but observationally we can see it happening.”
Another interesting fact is that the organic star dust that Kwok and Zhang studied has a remarkable structural similarity to complex organic compounds found in meteorites. As meteorites are remnants of the early solar system, the findings raise the possibility that stars enriched our protoplanetary disc with organic compounds. The early Earth was known to have been bombarded by many comets and asteroids carrying organic star dust. Whether these organic compounds played any role in the development of life on Earth remains a mystery.
It will also be interesting to see if this finding has an impact on research groups that look for life in the universe, such as SETI , considering that complex organic molecules have always thought to be markers of carbon-based life forms.
This artist’s concept illustrates the first known Earth Trojan asteroid (Credit: Paul Wiegert, University of Western Ontario, Canada)
By Tushna Commissarat
Looks as if the Earth has a cohort – one that has been hitching a ride with our planet’s orbit for a while now. Astronomers sifting through data from NASA’s Wide-field Infrared Survey Explorer (WISE) mission have discovered the first known “Trojan” asteroid orbiting the Sun along with the Earth. It has been known since 1772 that stable small bodies can share the same orbit with a planet or a moon – as long as they remain at stable points in front of or behind the main body. Such Trojan asteroids have been found orbiting Jupiter, Mars, two of Saturn’s moons and Neptune, but had not been seen for the Earth until now. This is because they are difficult to detect, being relatively small and appearing near the Sun from the Earth’s point of view.
Trojans circle around “Lagrange points” – gravity wells where small objects can be relatively stable compared with two larger objects, in this case the Sun and the Earth. The points that the Earth’s Trojan – called 2010 TK7 – orbits around are known as the L4 and L5 points, and are 60° in front of and behind the Earth, respectively. As they constantly lead or follow in the same orbit as the planet, they can never collide with it; so you can breathe a sigh of relief if you were worried about a possible armageddon.
“These asteroids dwell mostly in the daylight, making them very hard to see,” says Martin Connors of Athabasca University, Canada, lead author of a paper about the discovery published in Nature. “But we finally found one, because the object has an unusual orbit that takes it farther away from the Sun than is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at the Earth’s surface.”
The WISE telescope scanned the entire sky in the infrared from January 2010 to February this year. The researchers began looking for data for an Earth-bound Trojan using data from NEOWISE – a WISE mission that focused in part on near-Earth objects (NEOs), such as asteroids and comets. NEOs are bodies that pass within 45 million kilometres of Earth’s path around the Sun. The NEOWISE project observed more than 155,000 asteroids in the main belt between Mars and Jupiter, and more than 500 NEOs, discovering 132 that were previously unknown. The team found two Trojan candidates – of these, 2010 TK7 was confirmed as an Earth Trojan after follow-up observations were made using the Canada–France–Hawaii Telescope in Hawaii.
2010 TK7 is roughly 300 metres in diameter, at a distance of about 80 million kilometres from Earth. It has an unusual orbit that traces a complex motion near the Lagrange points in the plane of the Earth’s orbit, although it also moves above and below the plane. The asteroid’s orbit is well defined and remains stable for at least 10,000 years. For the next 100 years, it will not come closer to the Earth than 24 million kilometres. An animation, with a Star Wars worthy soundtrack, showing the orbit can be found below. (Image and video credit: Paul Wiegert, University of Western Ontario, Canada.)
A handful of other asteroids also have orbits similar to Earth. Such objects could make excellent candidates for future robotic or human exploration. Unfortunately, asteroid 2010 TK7 has not been deemed worthy of exploration because it travels too far above and below the plane of Earth’s orbit, and so would require a large amount of fuel to reach it.
By Tushna Commissariat
Despite gloomy weather conditions that threatened to cancel the launch altogether, NASA’s shuttle Atlantis has launched from the Kennedy Space Center. Marking the last and final flight of the Space Shuttle Programme – STS-135 – Atlantis and a four-person crew are on a 12-day mission to deliver more than 3.5 tonnes of supplies to the International Space Station (ISS). This final stock should keep the station running for a year. Although the countdown stopped briefly at 31 s before the launch, the shuttle had a “flawless” lift-off, according to NASA. It has now settled down into its preliminary orbit ahead of its rendezvous with the ISS this Sunday morning.
The image above is of the shuttle, taken shortly after the rotating service structure was rolled back yesterday at Launch Pad 39A at the Kennedy Space Centre in Florida (Credit: NASA/Bill Ingalls). Below is an image of the mission patch for this final iconic flight (Credit: NASA).
“The shuttle’s always going to be a reflection of what a great nation can do when it commits to be bold and follow through,” said astronaut Chris Ferguson, commander of the mission, from the cockpit of Atlantis minutes before the launch. “We’re completing a chapter of a journey that will never end. Let’s light this fire one more time, and witness this great nation at its best.”
Atlantis was the fourth orbiter built and had its maiden voyage on 3 October 1985. Atlantis had a number of firsts to its name – it was the first shuttle to deploy a probe to another planet, to dock to the ISS and the first with a glass cockpit! It conducted a final servicing mission to the Hubble Space Telescope in May 2009.
NASA has decided to retire its shuttle programme with this last flight because the vehicles are too costly to maintain. It now intends to contract out space transport to private companies. The hope is that this will free NASA resources to invest in a other programmes that will potentially send humans beyond the space station to the Moon, Mars and maybe even asteroids.
Atlantis is also carrying some rather unusual passengers – some simple yeast cells. The aim is to study the yeast cells as their genetic make up is remarkably similar to that of a human cell. This makes it an ideal system for studying genetic defects and understanding how these defects may manifest in human disease. In two separate experiments – conducted at the ISS – researchers will study the effect of microgravity on cell growth.
The video below has the crew of Atlantis talking about the “vibrancy of the ISS as a stepping stone for NASA’s plans for future human exploration beyond low Earth orbit”.