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
Tracing aromatic molecules in the early universe
23.03.2017 | University of California - Riverside
New study maps space dust in 3-D
23.03.2017 | DOE/Lawrence Berkeley National Laboratory
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences