Over to the moon
Prof Paul Singh
Till date, we have heard about the beauty, serenity, and tranquility of moon in the reel life only but now, in reality, we are going to get a lot of information regarding the surface and minerals on the moon. With successful launch of Chandrayaan-I at the head of the four-stage Indian built space vehicle, the Polar Satellite Launch Vehicle (PSLV), India joins the elite lunar club (US, Russia, Japan, China and European Space Agency) of space-faring nations.

Chandrayaan-II mission approved
Radhakrishna Rao
The Government of India has approved the proposal for India’s second lunar probe Chandrayaan-1 which will feature a robotic rover designed to land on the lunar surface. Chandrayaan-II planned to be built in tieup with Russia will be launched by means of the three-stage cryogenic fuel driven GSLV (Geosynchronous Satellite launch Vehicle) from SDSC. The rover will move on wheels on the lunar surface, pick up samples of soil or rocks, do a chemical analysis and send the data to the mother spacecraft orbiting around he moon.

Prof Yash Pal

THIS UNIVERSE 
PROF YASH PAL
How our earth is hanging in the vastness of space? What keeps it in its place?
The earth should not be seen as hanging in a place. It is moving. It is moving but it is subject to the forces of the sun and the other planets. The attraction of the sun is balanced by the centrifugal force of its movement. While the earth is not a prisoner kept in chains, it cannot be playful and run around like a child.

Over to the moon
Prof Paul Singh

Till date, we have heard about the beauty, serenity, and tranquility of moon in the reel life only but now, in reality, we are going to get a lot of information regarding the surface and minerals on the moon. With successful launch of Chandrayaan-I at the head of the four-stage Indian built space vehicle, the Polar Satellite Launch Vehicle (PSLV), India joins the elite lunar club (US, Russia, Japan, China and European Space Agency) of space-faring nations.

According to G. Madha-van Nair, Chairman, ISRO, in addition to upgrading India’s technological competence and providing challenging opportunities for planetary research to the younger generation, this mission would provide immense impetus to science and technology in India. The mission is aimed at two primary objectives:

i) Goal of harnessing the science payloads, lunar craft and the launch vehicle with suitable ground support systems, including Deep Space Station (DSN).ii) Integration and testing, launching and achieving lunar polar orbit of about 100 km, in-orbit operation of experiments, communication, telemetry data reception, quick look data and archival for scientific utilisation.

Once the spacecraft is put in the assigned orbit, it would be in a position to have high-resolution remote sensing of the moon in visible, near infrared (NIR), low energy X-rays and high-energy X-ray regions with specific objectives, which follow as:

i) Preparing a three-dimensional atlas of both near and far side of 
the moon.

ii) Chemical and mineralogical mapping of the entire lunar surface for elements such as Magnesium, Aluminum, Silicon, Calcium, Iron and Titanium; and high atomic number elements such as Radon, Uranium & Thorium.

iii) The availability of water on the moon for settling of humans in near future.

iv) The abundance of helium, used as fuel in nuclear fusion reactors, is yet another attraction to probe the moon. This is an area which needs to be pursued seriously for the mining of helium and ferrying it to the earth for power generation to meet the growing needs.

Chandrayaan-I is a spacecraft of cuboid shape of approximately 1.50 m side. It weighs 1304 kg at launch and would reduce to 590 kg when set in lunar orbit. It carries 11 scientific payloads on board i.e. six Indian and five from the US, Sweden, Japan, Germany and Bulgaria.

It is a 3-axis stabilised spacecraft using two star sensors, gyros and four reaction wheels.

The Indian Space Research Organization (ISRO) has built its Polar Satellite Launch Vehicle (PSLV) in the early 90s. Besides the launching of many Indian satellites, PSLV has also launched four satellites from abroad such as TUBSAT and DLR-Bird from Germany, Proba from Belgium and KITSAT from Republic of Korea.

Its reliability and maturity has made it fit for the first lunar mission. The upgraded version of PSLV viz., PSLV-C11 with a liftoff weight of 316 tonnes, is used to inject 1304 kg mass spacecraft at 240 x 24,000 km orbit around earth and the corresponding spacecraft mass is 590kg when the target lunar orbit of 100 km is achieved.

The power required during all phases of the mission would be provided through a canted single-sided solar array.

This deployable solar array consisting of a single panel generates 700W of peak power.

In case of emergency like during solar eclipse, spacecraft will be powered by Lithium ion (Li-Ion) batteries.

The spacecraft is also fitted with an X-band, 0.7m diameter parabolic antenna for payload data transmission to the ground station.

The spacecraft would make use of a bipropellant integrated propulsion system to reach lunar orbit and also for maintenance of altitude while orbiting the moon.

The system carries sufficient propellant for a mission life of 2 years, with adequate margin.

Chandrayaan-I is carrying scientific payloads which includes indigenously developed and some from international scientific arena. The indigenously developed payloads/ experiments are:

(i)The Terrain Mapping Stereo Camera (TMC) in the panchromatic band, having 5 m spatial resolution and 20 km swath, to take photographs of moon surface. (ii)The Lunar Laser Ranging Instrument (LLRI) having a height resolution of about 10m to measure the heights of mountains. (iii)The Moon Impact Probe (MIP) which will strike at the surface of the moon and will put Indian flag on the surface. (iv) The Hyper Spectral Imaging camera (HYSI) operating in 400-950nm band with a spectral resolution of 15nm and spatial resolution of 80m and a swath of 20km. (v) High Energy X-ray spectrometer (HEX) using Cadmium-Zinc-Telluride (CdZnTe) detector in the 30-250 keV energy regions with spatial resolution of 40km.

The ISRO has solicited proposals through an Announcement of Opportunity (AO) from International and Indian Scientific Community for participating in the mission by providing suitable scientific payloads.

After the successful launch of the Rs.3800-million Chandrayaan-I mission, ISRO is intending for more ambitious space projects in the years to come including landing a robot on the lunar surface and launching the Indian spacecrafts to other planets of the solar system.

The Lunar mission is a right step towards the exploration of outer space. To realize it, India and Russia have signed a Memorandum of Understanding for joint development of lunar rover and robotic arms to be used in the Chandrayaan-2 mission sometime scheduled for launch during 2011-12.

The writer is Professor of Physics, Dept. of Chemistry & Physics, CCS HAU, Hisar. 

Chandrayaan-II mission approved
Radhakrishna Rao

The Government of India has approved the proposal for India’s second lunar probe Chandrayaan-1 which will feature a robotic rover designed to land on the lunar surface. Chandrayaan-II planned to be built in tieup with Russia will be launched by means of the three-stage cryogenic fuel driven GSLV (Geosynchronous Satellite launch Vehicle) from SDSC. The rover will move on wheels on the lunar surface, pick up samples of soil or rocks, do a chemical analysis and send the data to the mother spacecraft orbiting around he moon.

While ISRO will develop the main orbiter, Russia’s Federal Space Agency will build the landing platform along with the rover. Though the exact landing site is yet to be identified, Aitken basin near the southern pole of the moon is one of the potential candidates. Chandrayaan-II is planned to be launched during 2011-12.

The main Chandrayaan-II orbiter will carry remote sensing instruments, a terrain mapping camera and nano meter hyper spectral imager capable of seeing in the visible, ultra violet and infrared regions. In addition, Chandrayaan-II orbiter will feature a low energy x-ray spectrometer with charge coupled device arrays, gamma ray, neutron and alpha spectrometers. Foreign payloads are likely to be accommodated in Chandrayaan-II.

ISRO has also hinted at a possible sample return to moon as a followup to Chandrayaan-1 though as yet it is in a very conceptual stage. Though for the moment, ISRO has no plan to take up a project for a manned mission to moon, and Indian human project to moon is not totally ruled out.

THIS UNIVERSE 
PROF YASH PAL

How our earth is hanging in the vastness of space? What keeps it in its place?

The earth should not be seen as hanging in a place. It is moving. It is moving but it is subject to the forces of the sun and the other planets. The attraction of the sun is balanced by the centrifugal force of its movement. While the earth is not a prisoner kept in chains, it cannot be playful and run around like a child.

Only those forces can slow it down that oppose its motion. These are mild forces of distant planets or the tidal forces of the sun. Without these forces it would go on moving without requiring any propulsion engines.

We need to get away from earthly notion that something that is not supported by pillars or chains is hanging and wants to fall down somewhere. There is no down except in the direction of the net force. Also we should remember that motion is relative. Furthermore the laws that apply in any frame of reference are equally valid in another frame moving at uniform motion with respect to the first frame. We know this is valid when we pour tea in a fast moving jet plane — the tea falls into the cup using the same skills we use at home.

In static electricity why do different objects have different charges?

Different substances have orbital electrons with varying strengths of binding with their atoms. So when you rub them together the atoms with less binding of their outer electrons would lose them to those which hold their electrons more tightly and even have the capability to attach an extra  electron round their atoms.  Incidentally this can happen only with materials that are insulators.

The material that loses electrons becomes positively charged and the  recipient  becomes negatively charged. Incidentally rubbing is required only to bring the two materials close together — you are not scraping electrons from one to the other.

Can resistivity or resistance be negative? If yes then how; If no then why?

I do not know how this thought occurred to you. Of hand I do not comprehend the possibility of negative resistance. Perhaps  you can give me the reason for this flight  of fancy or inspiration. Resistance certainly can go down to zero as in a superconductors. I suspect I am overlooking something subtle and deep.