Category Archives: Science

C/2015 G2 (MASTER) is first South African Comet discovery in 35 years

The first image of Comet C/2015 G2 MASTER (originally designated M503ujx before it was confirmed as a new discovery) taken by the MASTER-SAAO telescope on 8 April 2015. The image was produced from adding together four exposures taken in different coloured filters to produce a colour image of the field.

In the early hours of the 7th April, an un-manned robotic telescope, MASTER-SAAO, situated near Sutherland in the Karoo, discovered a new comet. This is the first comet to be discovered in South Africa since 1978.  The Russian – South African run telescope has been scanning the southern skies since it began operating in late December 2014, looking for “transients” – new objects which appear in the sky for the first time. Since then, over 60 new  objects have been discovered, most of them being erupting or exploding stars. However, the MASTER-SAAO telescope has just discovered its first comet. 

Comets are often described as “dirty snowballs”  and are composed of a ball of frozen ice with chemical compounds and dust mixed in. As a comet approaches the Sun it begins to melt resulting in a halo of gas and dust surrounding the solid nucleus called the coma. The Solar wind pushes the gas and dust released away from the comet resulting in the beautiful tails that we see associated with comets. There are actually two tails to a comet, one is made of gas (ions) which comes from the frozen compounds melting, the other is a dust tail again caused by the gases from the nucleus evaporating taking the dust with them. Astronomers are interested in studying comets because they represent the oldest and most primitive objects in the solar system and give astronomers an insight as to what conditions were like at the formation of our solar system.

The MASTER-SAAO telescope at Sutherland.

The recently discovered comet has been officially named “Comet C/2015 G2 (MASTER)” and the discovery was confirmed on the 10th April by the Minor Planet Center, based at the Smithsonian Astrophysical Observatory in the USA. It is the 20th comet discovered so far in 2015, and is currently heading rapidly south through the southern skies, brightening as it does so. Currently, the comet is about 180 million km from the Earth. It will make its closest approach to the Sun, at 116 million km (just a little further from the Sun than Venus), on the 23rd May when it is expected to be at its brightest. Although the comet is not particularly bright, the image taken by the MASER-SAAO telescope shows a distinct ion (gas) tail, produced by the interaction of the Solar wind and the comet. As it brightens, the comet should be visible in dark skies (i.e. away from city lights) using binoculars. The last comet discovered in South Africa, Comet D/1978 R1 (Haneda-Campos), was co-discovered by Jose da Silva Campos, observing from Durban on 1st September 1978, and an astronomer in Japan, Toshio Haneda.

The MASTER-SAAO facility is one member of a network of telescopes operated by the Lomonosov Moscow State University’s Sternberg Astronomical Institute. Most of the other telescopes in the network are located in Russia but there are two telescopes in the network located in the Southern Hemisphere: the MASTER-SAAO facility just outside Sutherland and a smaller telescope in Argentina. The Sutherland facility is a joint project with the South African Astronomical Observatory, aimed to discover and study southern optical transients – new objects which suddenly appear in the sky. It is the first transient detection system to be situated at Sutherland and will eventually be joined by another similar system, MeerLICHT, later this year. Discoveries from these telescopes will be followed up by more intensive studies using other South African telescopes such as SALT and MeerKAT (once it begins operating) and also the HESS gamma-ray facility in Namibia.   

Call for Scientific Proposals Announcement

The call for Scientific Proposals for the Africa2Moon Mission will be announced at a press conference on Friday 13 March 2015 at 2;30pm South African Standard Time.

An open invitation has been issued to attend the announcement & Q&A session in person at the Cape Town Science Centre or via a Google Hangout.

After the announcement online submission will be available on this website.

Screenshot - click to view
Screenshot – click to view

Probing the Universe with the Square Kilometre Array

Scientists from South Africa are playing a leading role in developing the science which will be done with the world’s largest telescope, the Square Kilometre Array.

The SKA telescope, to be built in Australia and South Africa, will allow scientists to look far back into the history of the universe and will give much more detail than before on how the universe has evolved over 14 thousand million years. More information will be obtained on how stars, galaxies and clusters of galaxies formed and how they have changed since the Universe was young. This will allow for the plotting of a 3D map of the Universe.

The international SKA Organisation, which includes eleven countries, is bringing up to date the science case for the telescope. South African scientists are playing a leading role in many of the working groups. The SKA Cosmology Working Group is chaired by Roy Maartens, SKA Research Professor at the University of the Western Cape (UWC). Professor Maartens and Professor Mario Santos, also a Research Professor at UWC, with astronomers from South Africa and the other SKA member countries, have played a leading role in setting out the SKA science.

Roy Maartens says: “Researchers here have devised a means of using the world’s largest telescope in new ways that will help shape the future of cosmology.”

Mario Santos says: “Usually a map of the Universe is made using galaxies as tiny beacons of the large scale structure of the Universe. This is quite demanding as it requires the mapping of large numbers of galaxies across the sky.”

“The survey we are proposing will measure the emitted radiation from all the hydrogen atoms spread across the Universe without actually detecting galaxies. This will make it easier to survey all of the sky across cosmic times, allowing the phase 1 of the SKA to become an extremely competitive cosmology machine,” he adds.

“By making these huge, 3D maps of the Universe we will be able to test the limits of General Relativity and maybe find some signature of new physics on these large scales which can shed light on the true nature of dark energy. Moreover, we can also look for imprints of what happened at the very beginning of the Universe,” added Santos.

An experiment like this, says Santos, using intensity mapping, has never been done before. The largest 3D maps of the large scale structure of the Universe have been done using optical telescopes. The current project will be about 50 times larger. Other future experiments, such as the Euclid satellite, will be able to also probe a large fraction of the Universe, but none will match the SKA in terms of size and depth.

Maartens adds: “It will be like making a movie of the Universe from a young age, when it was only about 2 billion years old, until today when it is about 14 billion years old. The movie will be low resolution but enough to test the fundamentals of cosmology.”

When the actual survey with the SKA comes online, a large team will be required to deal with it. Once the phase 1 of the SKA is built, around 2023, it will take about 2 years to complete the survey.

SKA SA has been crucial in promoting the build up of the required researchers to lead such an effort. However, says Santos, they don’t have to wait for the SKA to start, before doing observations. “Tests are already being conducted using the KAT7 system with the full support of the KAT7 staff and we plan to start tests with MeerKAT in just a year, during the early science phase,” Santos stated.

He added that the SKA telescope is like a “physics lab”, allowing many different experiments to be pursued. There will be other surveys that in combination with this one, will allow scientists to push the limits of our current knowledge of the Universe.

Reference information

Astronomers preparing to map the Universe with largest radio telescope ever built

SKA Website

WATCH: The real Gravity

With the movie Gravity premiering on DSTV101 tonight, 28 December 2014, for African Viewers, we thought it would be a good opportunity to highlight the real issue of Space Debris & the Kessler Syndrome:

OBJECTS IN SPACE 1957-2010

Kessler Syndrome
The Kessler syndrome (also called the Kessler effect, collisional cascading or ablation cascade), proposed by the NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low Earth orbit (LEO) is high enough that collisions between objects could cause a cascade—each collision generating space debris which increases the likelihood of further collisions. One implication is that the distribution of debris in orbit could render space exploration, and even the use of satellites, unfeasible for many generations.
Source: Wikipedia

Bill Maher & Neil deGrasse Tyson On Kessler Syndrome

Is there science still to be done on the Moon?

Impact Bombardment
Figure 1.  The leading hypothesis for the origin of the Moon involves a huge collision between the Earth and a planet half its size.  Some of that colliding material was added to the Earth, but a large fraction of the impact debris went into orbit around the Earth.  The orbiting material accreted together to form the Moon.  The CLSE team will be testing that hypothesis by examining the chemical composition of samples from the Moon and the ages of those samples.

Impact Bombardment Throughout the Solar System
Impact events are an intimate part of the formation of planets, both during the initial accretional phase and late in the growth of a planet when giant impact events may dramatically alter the final outcome. Large collisions, for example, have been implicated in the formation of the Moon from the Earth (Figure 1), the stripping of Mercury’s mantle, the northern-southern hemisphere dichotomy of Mars, and the formation of Charon from Pluto. Periods of enhanced impact bombardment of post-accretion planetary surfaces have also been deduced from solar system exploration studies. Apollo, for example, demonstrated that the Moon was heavily cratered sometime during the first ~600 million years of its existence in what has been termed by some to be the period of Late Heavy Bombardment (LHB).

Dusty circumstellar disks around young stars outside our solar system indicate the collisional evolution of young planetary systems can be violent. Initial Spitzer Space Telescope data indicate that some systems show dust signatures well above the average at ages from 100 to 600 million years old. Observations support the idea that the ~350 million-year-old A star Vega and the ~2 billion-year-old G star HD 69830 recently experienced collisions between large planetesimals that have generated these elevated dust signatures.

The consequences of the collisional evolution of young planetary systems, including our own solar system, are profound. It now seems clear that:

  1. Early bombardment of planets can completely resurface them.
  2. These impacts can alter the physical and chemical state of (and/or blow-off) planetary atmospheres.
  3. The bombardment can make surface conditions unpalatable for biogenic processes.
  4. In contrast, the impacts can also create subsurface environments that are suitable crucibles for pre-biotic reactions and possible habitats for any life that develops.
  5. The impacting objects and interplanetary dust that accompanies them can deliver important biogenic components like water, carbon, nitrogen, sulfur, and phosphorus).
  6. The impacting objects may also be the source of important siderophile (iron-loving) element addition.

The Apollo Legacy
While it is generally recognized that the impact cratering rate was more intense early in solar system history, it is not clear how that rate evolved. Some investigators have suggested there was a smooth decline with time, while others have suggested there were one or more episodes of particularly intense activity superimposed on a background decline in the impact rate.

The Apollo and Luna missions provided the first opportunities to investigate this issue. Argon-argon isotopic analyses of Apollo and Luna samples suggested three to possibly six of the impact basins on the nearside of the Moon had been produced between 3.88 and 4.05 billion years ago. Additional analyses of Apollo samples indicated the U-Pb and Rb-Sr systems had been disturbed nearly uniformly at ~3.9 billion years ago, which was attributed to metamorphism of the entire lunar crust by a large number of asteroid and/or cometary collisions in a brief pulse of time, <200 million years long, in what was termed the lunar cataclysm. A  growing number of ~3.9 billion-year-old impact melt ages from the Apollo and Luna collections seemed to confirm the pattern. It was suggested that the decline in the impact rate was not smooth, but punctuated by at least one large influx of material.

The hypothesis of an intense period of bombardment ~3.9-4.0 billion years ago is still controversial, however. There are currently several models under consideration. Some investigators have argued for a lunar cataclysm ~3.9-4.0 Ga and a relatively low impact rate between ~4.4 and 4.0 billion years ago (lower curve in Figure 2). They also argued that the duration of the cataclysm may have been as short as 10-20 million years long. Others have argued that the time span of the bombardment may have been longer and/or that the impact rate prior to ~3.9-4.0 billion years ago was relatively high (upper two curves in Figure 2). In all cases, it is generally agreed that there was a significant decrease in the lunar cratering rate after ~3.8 billion years ago when the last basin-forming impact occurred.

Some investigators have suggested that sampling issues, particularly on the Moon, cloud our ability to resolve the impact cratering record prior to ~3.9 billion years ago, and do not accept the notion of a cataclysm on the Moon, asteroids, or any other body in the solar system. There are also interesting discrepancies in existing data. While Apollo samples suggest a relatively abrupt decline in the impact-cratering rate ~3.85 billion years ago, lunar meteorite data and chondritic meteorite data suggest it may have been drawn out until 3.5 to 3.4 billion years ago. To test these ideas, the CLSE team will analyze samples from the Moon and asteroids to determine the timing and magnitude of impact events that occurred in the Solar System.

Although the lunar cataclysm hypothesis is one of Apollo’s highlights and remains the number-one science priority of NASA (NRC 2007), it is representative of a broader range of questions. We now understand that impact cratering is the dominant process affecting the lunar surface. There are hints that the Moon’s origin may be intimately tied to a collisional event (the giant impact hypothesis) when the accretion rate was much higher (Figure 2). We have also gleaned from Apollo that impact events have produced a unique lunar surface regolith, which itself is a record of meteoritic and heliophysical processes and the medium with which future lunar surface exploration will be immersed. We have designed an integrated interdisciplinary study of impact processing of the Moon that tackles the highest science priorities identified by the NRC for NASA.

Source: NASA Center for Lunar Science & Exploration