Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Close encounters with Mars


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:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of 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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>