Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Close encounters with Mars

25.08.2003


On 27 August 2003, Mars is less than 56 million kilometres away - approaching closer to our planet than it has done in over 60 000 years.



About the same time as this closest approach, Mars Express passes the halfway mark of its journey, in terms of distance along its trajectory. On 1 September 2003, as it hurtles through space at 10 800 kilometres per hour, the spacecraft will have covered over 242 million kilometres, half of the total of 485 million kilometres needed to arrive at Mars. Note that the distance travelled is not the same as the distance between the Earth and Mars.

At first glance, you might think that this time would be better than three months ago to launch a spacecraft to Mars, given the advantage of a shorter route. However, planning interplanetary journeys is more complicated than just taking account of the distances.


Playing catch up

This is because the planets are also moving in their respective orbits. If you want your spacecraft to rendezvous with another object in space, you must carefully time its launch so that the orbits overlap at some point in the future.

Imagine the Solar System as an athletics racetrack. If you were watching a 400-metres race from the centre of the track and wanted to intercept one of the runners taking part, you could simply chase the runner you want to catch. If you are fast enough, you might eventually catch up but only after using a lot of energy and travelling a long way.

A much better way to catch your athlete is simply to walk across the centre to the other side of the circular track. It is a much shorter distance and you use a lot less energy and time getting there. You calculate your walk so that you arrive at the other side of the track at the same time as they do. Too early and you are waiting for them. Too late and you have missed them completely - you would have to wait one lap until they came around again.

In spaceflight, straight-line paths do not exist for the same reason. All planets move in long, curved paths around the Sun in either circular or elliptical orbits. To reach Mars, the Mars Express probe is now on a trajectory, an arc-shaped path, which gradually makes its way outwards to intersect the orbit of Mars about six months after launch.

It is no coincidence then that the fleet of spaceprobes now travelling to Mars was launched within weeks of each other in 2003. Even with the relatively close positions of the planets, which would cut journey times, scientists still needed to calculate the shortest trajectory between the orbits of Earth and Mars. It makes sense that this occurs around the time of closest approach. Once the shortest path has been established, you can then work back to get the actual launch dates.

All in a row

Though Mars will be closest to Earth on 27 August 2003, ’opposition’ comes on 28 August 2003. Astronomers call the moment when the Sun, Earth, and Mars form a straight line opposition. Since we are closer to the Sun than Mars, this is also when we are overtaking Mars in our respective orbits.

At a distance of exactly 55 758 006 kilometres from Earth, the Red Planet will be brighter than Jupiter and all the stars in the night sky, outshone only by Venus and the Moon. You will not see anything gigantic in the sky, but you will be able to see Mars’s distinctive red-orange colour. Amateur astronomers with good-sized telescopes will be able to see some of the planet’’s features, such as the polar ice cap, dark surface features, and perhaps even storm clouds.

Interesting as this closest approach is, professional astronomers will be looking forward to even better things. Probes that orbit the planet have studied Mars and some spacecraft have even landed on it. Later this year, our knowledge will increase dramatically when the flotilla of spacecraft, including Europe’s Mars Express, approaches the Red Planet.

Mars Express will help to answer the questions of whether there has been water, and possibly life, on Mars. It will be mapping the Martian subsurface, surface, atmosphere, and ionosphere from orbit and by conducting observations and experiments on the surface.



Monica Talevi | alfa
Further information:
http://www.esa.int/export/SPECIALS/Mars_Express/SEMILAZO4HD_0.html

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>