Friday, December 18, 2015

ASTROSAT vs The Giant Hubble

A TV program on the legendary Hubble Space Telescope, HST (Hubble's Cosmic Journey, National Geographic), prompted me to write this piece on the recently launched Indian space telescope called ASTROSAT.  The purpose of Hubble Space Telescope is to break the barrier of 1-arc second seeing limit (full moon is about 1,800 arc-seconds across) from the ground which arises due to the atmospheric disturbances. NASA had achieved this by a mammoth effort of grinding a 2.4-meter glass to the curvature accuracy of 1/800,000 th of an inch and placing the school bus size object weighing 11,110-kg in 550-km orbit. ASTROSAT is India's  multi-wavelength telescope geared to look at the stellar objects primarily in UV, X-ray regions of the EM spectrum. In that TV program, the sweet voice of John Grunsfeld conveying his strong bond he had created in repairing the Hubble more than one time. Hubble is the most sophisticated optical experiment of humans in the space which has been working for 25-years and is going great guns.

In the back drop of this legacy; enters here,  the young-aspiring Indian beauty, ASTROSAT. In a typical Indian style of small-simple but effective, this telescope carries the same heritage as that of the Indian Chandrayaan-I (moon  mission) and MOM (Mars mission).  The idea of Indian scientists is to perform front line research from the existing experience in the country (X-ray astronomy); and hence majority of the hardware which went into is in the X-ray regime of EM spectrum. Considered to be a small size (in comparison to others) space telescope, it weighs 1513-kg at the time of lift off; it is basically a multi-wavelength telescope in a near equator orbit of around 650-kms radius.

Apart from performing the deep field survey of the Universe in the UV region; ASTROSAT's wish list covers a wide range of phenomenon which are taking place in the universe:
a. studying the high energy processes of binary star system (neutron star-black hole),
b. estimation of magnetic field of neutron stars,
c. look for star birth region beyond our galaxy,
d. detecting the new briefly appearing bright x-ray sources in the sky.

If I could drift a bit beyond the popular level flow of this presentation; here is the list of payloads, the instruments which are very well thought over and put together by the host of Indian research institutes: TIFR, IIA, IUCAA, PRL and RRI.

Credit: ISRO
The details given above emphasises that the Optical and UV region is covered by a single detector; great efforts have been put to cover a very wide range of X-ray based 4-instruments.

As they say, the proof of the pudding is in eating.... the ASTROSAT has come out with a flying colours as soon as its eyes were made to open.

On 17th November, when the Swift observatory of NASA made its 1000th observation of Gamma Ray Burst (GRB), the ASTROSAT's CTZI indeed picked the same object and hence the sweet news of success to the eagerly waiting Indian scientists. The observations are reported here .


Comparing Hubble Telescope with the ASTROSAT would be like comparing the legend Carl Lewis to that of a young athlete or in Indian terms, comparing Sachin Tendulkar to a Ranji trophy player. Without offending anyone, I must also add that both of these sport legends have indeed followed the same nascent stages. Hubble is a huge optical telescope to peek deep into the dark patches as seen from the ground telescopes. This was possible due to the avoidance of atmospheric disturbances. Where as, ASTROSAT is a multi-wavelength observing telescope; may not be huge in size but carries a state-of-the art X-ray detectors and a combined UV-Visible detector in aiming the similar deepest in-accessible "dark regions". With the success of operation of most of the detectors, it is only the time which is going to unravel the worthiness of all the hard work of Indian scientists. Best of luck INIDA..... 

Hubble Space Telescope

As has been referred here, Hubble is a legend in opening the eyes of humanity into the darkest regions of skies. Hubble basically is an optical observatory with an viewing ability of better than 0.1-arc second, having the 3-different types of sensors: i. Camera, ii. Spectrograph and iii. Photometer. A daring 5-space walks had fixed the flaw in achieving the intended goals of Hubble imagery; a total of 4-repairing attempts have kept the instrument in its best abilities.

Here is the summary of few greatest achievements of Hubble:
  • Identification of dark matter which is otherwise invisible and comprises around 23% of the entire universe could be modelled into 3-D from the observations of Hubble
  • Hubble discovered 2-new moons of Pluto : Nix, Hydra
  • Identification of star forming regions, e.g. Orion nebula
  • Picking up gamma ray bursts (GRB) and resolving the mystery around them
  • Capturing the famous collision of comet Shoemaker-Levy with planet Jupiter
  • Helped to identify the dark energy which is responsible for expansion of universe
  • Super massive black holes may be lurking in many galaxies that have bulge of stars at the centre
  • Observing the atmosphere of exo-planet (in Visible)
The list goes on.... and is still counting.....

The humble : ASTROSAT

The unique capabilities of ASTROSAT lies in its multi-wavelength capabilities of observing stellar objects.
  • The Large Area X-Ray Proportional Counter (LAXPC) stands out among all the available space telescopes (RXTE, HEXTE, SAX); by offering almost 3-times larger area at 40-keV energy x-rays.
  • The LAXPC will also offer best timing studies; helping the observers to study the strong gravity regions around neutron stars and stellar mass black holes
  • LAXPC will also serve  as a complimentary instrument for the present/upcoming spectroscopic observations (Chandra, XMM-Newton, NuSTAR, ASTRO-H)
  • Sensitive hard X-ray spectroscopy
  • Wide spectral coverage : UV, 0.3-150 keV

RXTE : The Rossi X-ray Timing Explorer
HEXTE : High Energy Timing Experiment
SAX: Beppo SAX, Italian Dutch Satellite for X-ray astronomy
MOM: Mars Orbiter Mission

Wednesday, September 30, 2015

Water on Mars

After the discovery of bone dry moon to be holding traces of water molecules... Water on Mars means a lot to the human race. It is not a meagre scientific result where a 9-year old space craft revolving around Mars and 4-years old results have shown liquid water to be flowing during the summer on Mars; rather, these results have re-kindled new hopes of finding life on Mars, as per Michael Meyer, NASA's Mars Exploration Program. Of course, the intelligent, eager and inquisitive human's quest of leaving earth has found astronomical levels of adrenaline pumping into their blood streams.

This is the picture released by NASA which speaks tonnes of words on how the newly appearing streaks, called the recurring slope lineae (RSL)... held the secrets under their belly for so long that it took a smart under graduate student, Lujendra Ojha from Georgia Tech to figure out that these are actually hydrated salts which appear only when the ambiance reaches -23 C and above. In a way, the salts are helping the ice (water) to melt at much much lower temperatures; just as salt on roads here on Earth causes ice and snow to melt more rapidly.

Credit : NASA
SECRETS unravelled..

The dark streaks seem to be appearing in the summer and would again vanish as the temperature dips. It is only due to the long lasting mission Mars Reconnaissance Orbiter (MRO) and the versatile instruments it is carrying; that the keen observations of this undergrad student along with his team members that they found a way to unravel the secret beneath these streaks.

Ojha and his team first created a 3-D model (digital terrain map) utilizing the stereo information from  High Resolution Imaging Experiment (HiRISE) camera of MRO. The image is draped with the spectral information from Compact Reconnaissance Imaging Spectrometer (CRISM) of MRO. The spectrometer component of the overlaid image shows information about the hydrated salts at the multiple RSLs.

Ojha and his co-authors interpret the spectral signatures as caused by hydrated minerals called perchlorates. The hydrated salts most consistent with the chemical signatures are likely a mixture of magnesium perchlorate, magnesium chlorate and sodium perchlorate. This study of RSL detected perchlorates, now in hydrated form. This also is the first time perchlorates have been identified from orbit.

Another example of Dark Streaks on Garni crater..

Credit: NASA

Thursday, August 6, 2015

Breakthrough Listen - Search for Aliens

"Is there an intelligent life beyond Earth? " this question has been bothering the human race as far as 19th century. The Serbian-American Scientist Nikola Tesla proposed to send signals to Martians (1890); he claimed to have received unusual signals, calling them to be from "another world". The project, Search for Extra Terrestrial Intelligence, SETI, 1960 by Frank Drake, USA was to look for radio signals sent out by intelligent life in the universe.

The declaration of 100-million dollars fund by the Russian investor Yuri Milner with a surprise addition of Stephen Hawking in his team, the project "Breakthrough Initiatives" would certainly change the fate of SETI search. Milner, a physics graduate turned investor is known for turning coal into gold, with his investments bringing a new tide into the businesses (e.g. facebook, twitter, alibaba, xiomi, flipkart....); lets hope the same for SETI.

How is it done??
First strategy: Search for the radio signals in the nearby 100 million stars hoping that civilization living in their planetary system may be intelligent enough to have a radio active utility in their routine works, e.g. air traffic control or any other communications.

Since the past studies of SETI have strongly suggested that the radio signals from extra-terrestrial signals could come only from the far away sources and they could be extremely strong, an alternative hunt would also be planned.

Second strategy: Here the entire plane of milky-way galaxy (where we live) and the central zone will be studied in detail to cover more than 100-billion stars in the shallow region (meaning far away). Apart from this, the survey would also stare at 100-galaxies  comprising of 10s of trillions (1000-billion or million-million) of stars, each star having its own planetary system.

To accomplish the above said goals; the plan is to spend one-third of the funding in buying 20% of the 100-meter diameter Green Bank radio telescope at West Virginia and a substantial amount of time on Parkes 64-meter telescope in Australia for 10-years.

100-meter Green Bank radio telescope
Another one-third amount of funds are planned to develop very high sensitive receivers to listen to billions of narrow frequency channels in 1-10 GHz, a  region which covers best of the radio signal regimes which passes through the earth's atmosphere and also clean from the cosmic background . 

Breakthrough Listen will also be taking up observations in visible light region on the 2.4-meter Lick observatory's  planetary finder telescope. This would serve as an additional tool to support and confirm the region from where one hopes to pick POSITIVE signs of civilization.

Example: As per a rough estimate, the present studies (at Green Park) can pick up signals: "If an alien civilization living on a planet orbiting around any of the 1000 stars closest to us from a common air traffic kind of communication signals". 2. The optical signals monitored at Licks observatory would be able to pick 100-watts of light from the planets of stars which are within 4-light years away from ours.

Prominent SETI attempts:
A British radio astronomer, Antony Hewish and his post doc Jocelyn Bell studying the inter planetary scintillations of compact radio sources came across a set of radio sources displaying very regular and fast packet of signals. Unable to identify the source they went on to name them "little green men". Later the team went on to discover a new set sources called Pulsars; Anotny Hewish getting a noble prize (1974) for this discovery.

The famous ISRO-Balloon experiment, where the Indian scientists lead by Dr. Jayant Narlikar have successfully found bacteria in the stratosphere of earth, at an altitude of 20-40 kms. The three group of bacteria to be identified after the gene sequencing technique have been found for the first time (Reference). Though the Indian experiment may not fall under the LISTEN category, it does stand out as an outstanding effort of humans to reach out extra terrestrial life. India can certainly play a big role in this project; Milner goes on record to say that the idea of pumping this money is to instigate young minds towards science... is any body listening????

Bottom line!!
Though the present initiative may increase the SETI search by 100-times in the form of more sensitive tools (a rough estimate); it may take even generations to get to listen to the super civilization living away from our world. But surely enough... Milner has certainly initiated a giant step towards SETI...

Like to give credit to few press reports appearing in the internet after the declaration of Breakthrough Initiatives project on 20th July at the Royal Society, London, particularly to a good piece of article appearing in the Sky and Telescope by Alan MacRobert.

Thursday, July 2, 2015


Key words: New Horizons, Alan Stern

The NASA page of New Horizons says.... 10-Years..,5- Billion kms; truly the human aspirations are racing towards the edge of solar system with an astounding speeds of 80,000 km/hour. To be able to reach Pluto, the New Horizons space craft has to take a slingshot from the giant planet Jupiter. The scientists are going to peek into the new frozen world of Pluto on 14th July 2015 at a distance of just around 12,500 kms having to view football size images with 48-meter resolution. Where as, after its discovery in 1930, Pluto has just been a dot to the best possible astronomical observations from earth, except for few (10-12) pixel across image appearing in the Hubble Space Telescope in 90s. Why are the scientists so excited???  they say.... they have no idea.. may be it is the thickest atmosphere or gaseous jets streaming out.... anything.... so little is known.

New Horizons, Credit : NASA, 
New Horizons (NH).. an unique attempt?
Voyager-1 (Sept-1977) which has crossed the solar system now, had opted for Titan (Saturn's moon) as a compromise to bypass Pluto's flyby. Voyager-2 (Aug-1977) never had a trajectory to flyby Pluto. Then comes... New Horizons (2006)... fully geared to explore this dark world at its gory details. NH got the best opportunity to catch up with the celestial windows to be able to sling shot towards Pluto before the planet drifts further away and the atmosphere it holds getting frozen. As per the inspirational posts from Alan Stern, PI, that every care has been taken to avoid any collision the space craft may suffer due to the un known world around Pluto. "It was a relentless effort of around 2,500 NASA employees's effort that is going take us into these unknown worlds" says Alan Stern.

The Space craft:
To quote NASA, the piano sized space craft weighs 478 kilograms, with the lead role taken by the Southwest Research Institute, APL-JHU and contributions coming from (GSFC, JPL, KSFC, UC, Stanford...) many other institutions, to say a typical American heritage. Its a technological marvel running on a single radio-isotope thermoelectric generator of 200W capacity provided by a 11-kg Plutonium dioxide. Most of the instruments working at an average power of 5W (~ night lamp) and with the data being transmitted via 2.1-m antenna, a must for an object 5-billion kms away and the communication taking almost 9+ hours both ways. 

Instruments, Credit: NASA

The 7-instruments are like gems, hand picked with 10s of deliberations carried to get the maximum from the un-known worlds. In my priority list:
1. LORRI, the telescope/camera comes first. Dubbed as the hawk eyes of New Horizons, it is basically a black and white digital camera with a 20-cm telescope, but built to work in a hostile cold environment. On 14th July, LORRI will be beaming football size images with an unprecedented 50-meter resolution, a life time opportunity for all the planetary scientists. 
2. RALPH, though called as the "main eye", but a complex mixture of instruments comprising of three panchromatic imagers, four color imagers and a spectrograph. It will offer an abundance information on surface geology, morphology and thermal features.
3. ALICE is an imaging UV spectrometer to study the composition of Pluto's atmosphere. A smart baby with a built-in telescope and a huge spectral coverage to study ionic to neutral species.
4. REX, a smart idea of employing occultation technique (looking down to earth's DSN signals via the target atmospheres) to measure pressure, temperature of atmospheres of Pluot and Charon.
5. SWAP, to measure solar wind around Pluto, 6. PEPSSI to look for energetic particles, last but not the least 7. SDC a student dust counter, developed by the students to measure microscopic dust grains produced by the collision among asteroids, comets and KBOs.

Pluto Picture of the Day..... (updated daily...)

Mountain range discovered by NH on 14th July in the Tombough region from a distance of 77,000 km Credit: NASA.

Another secret of Pluto revealed, as NH was moving past Pluto, it captured the haze around Pluto extending to 130 km. Credit: NASA.