Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Timing is critical as launch windows approach

06.09.2002

There will be greater tension than usual among engineers and scientists at Europe`s spaceport at Kourou, French Guiana, in January 2003, as they gather to see ESA`s comet-chasing spacecraft Rosetta departing on its long journey. If it is to keep its rendezvous with Comet Wirtanen in 2012, Rosetta must lift off on its Ariane-5 launcher no sooner than 03:40 CET on 13 January 2003 and no later than the end of that month.

This span of suitable dates is called a launch window. For interplanetary missions, such windows are much stricter than for satellites orbiting the Earth. To send a spacecraft from the ever-moving Earth to a planet or a comet following another course through space is highly complicated. Timing is everything. Before it can meet Comet Wirtanen, far out in space, Rosetta first has a series of planetary appointments to keep. With each close fly-by of a planet, it receives an energy boost because of the planet`s gravitational pull. The spacecraft is due to pass by Mars in August 2005, then do high-speed fly-bys of the Earth in November 2005 and November 2007.

In a way, Rosetta is like a passenger on a train journey involving several changes. Unless the first train leaves right on time, with the spacecraft on-board, it will miss the later connections. If it departed after 31 January 2003, Rosetta would be unable to reach the target comet.

"The cosmic clock of the Solar System fixed our launch date when Comet Wirtanen was selected as Rosetta`s target ten years ago," comments John Ellwood, project manager for the mission. "Although there are risks in a precise, rather short launch window, it`s had the advantage that everyone concerned knew there was no room for discussion - they had to be ready."

Besides the restricted span of launch dates, there is also a tight limit on the time of day at which Rosetta can leave Earth. Because the Earth rotates, Kourou must be correctly positioned in relation to the direction in which the spacecraft must head off, on the first leg of its interplanetary journey. The daily window is about 20 minutes, during which time the Earth rotates through 5 degrees.

In May 2003, similar concerns about a launch window will preoccupy the engineers and scientists of ESA`s Mars Express mission, at the Baikonur Cosmodrome in Kazakhstan, in the former Soviet Union. There the launcher will be a Soyuz-Fregat rocket. Scientists have always planned to use the especially favourable relative positions of Earth and Mars occurring in mid-2003 (and not repeated until 2020) for Mars Express to have an express flight to the Red Planet.

Opportunities to fly to Mars occur every 26 months, but the travelling distance varies a lot because the orbit of Mars is elliptical, that is, egg-shaped. The 2003 opportunity coincides with a time when the Earth is about to overtake Mars, as the planets orbit around the Sun, and when Mars happens to be in the closest sector of its orbit. The Mars Express launch window opens at 20:41 CET on 23 May 2003 and closes at 17:47 CET on 21 June 2003.

Almost nothing in space stands still with respect to Earth, so ESA`s scientists will have to be careful that their craft, Rosetta, leaves Earth at the right time and in the right way. The spacecraft has a long trip ahead.

Monica Talevi | AlphaGalileo
Further information:
http://www.esa.int

More articles from Physics and Astronomy:

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

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: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>