Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Femtoseconds lasers help formation flying in space

06.10.2009
The National Physical Laboratory (NPL) has helped to establish that femtosecond comb lasers can provide accurate measurement of absolute distance in formation flying space missions.

NPL, along with collaborators, produced technical reports for the European Space Agency. The conclusions demonstrated that the lasers were a suitable method for measurement in such missions.

Formation flying missions involve multiple spacecrafts flying between tens and hundreds of metres apart, which autonomously control their position relative to each other. The benefit of such missions is they can gather data in a completely different way to a standard spacecraft – the formation can effectively act as one large sensor.

Measuring absolute distance between the formation spacecraft is critical to mission success. Femtosecond comb lasers are an accurate way of making such measurements. The lasers emit light with very short pulses – each lasting just a few femtoseconds. A femtosecond is one billionth of one millionth of a second. The short pulses allow time of flight measurements to be used to determine distance to a few microns.

For example, in the proposed International X-ray Observatory mission, due to launch after 2020, it is thought that the 25 metre spacecraft will require highly accurate measurement of the absolute distance between the front and back of the spacecraft because the craft's body will be flexible.

For the x-ray images to stay in focus, the position and orientation of the mirror at one end will have to be known, and controlled, to roughly 300 microns in length and 10 arc seconds in angle. Otherwise the telescope will not be able to resolve an image and the mission would fail.

Achieving this accuracy is enormously challenging on board a spacecraft. Instrumentation requires such accuracy, but must also be robust enough to survive launch and the ravages of space.

The other challenge in formation flying is achieving the formation itself, which is done once the spacecrafts reach the appropriate region of space. The spacecraft orient themselves in relation to each other by plotting their positions relative to known stars, and then establish their lateral positions via laser pointers. Once the formation is established, it can be maintained via highly accurate absolute length measurements between the spacecrafts.

These kinds of missions could answer a lot of the 'big questions' in astronomy and cosmology – like 'is general relativity correct?', 'how did the universe develop following the Big Bang?', and 'where do all the magnetic fields in the universe come from?'.

Another mission, called LISA (Laser Interferometer Space Antenna) is being planned to look for gravity waves. This will involve three craft flying approximately 5 million km apart. In this case it is not necessary to know the absolute distance between the crafts, extremely small changes in their separation on timescales of 10 seconds to 10,000 seconds could be a sign that gravity waves have been detected.

Such missions stand to benefit from this project and the use of femtosecond combs, and a number of groups worldwide are developing other systems using such technology as distance measuring instruments.

Prototype systems will need to have uncertainty claims verified by a national standards laboratory, such as NPL. They will also need to fulfil strict specifications on size, weight and power consumption and undergo other tests (for example the system's ability to withstand strong gravitational fields or radiation) so that they can become fully 'space qualified'.

The European Space Agency (ESA) project to determine the suitability of femtosecond combs was known as 'HAALDM' (High Accuracy Absolute Long Distance Measurement). It involved NPL, Menlo Systems, the Laser Centre Vrije Universiteit Amsterdam, and Kayser-Threde.

David Lewis | EurekAlert!
Further information:
http://www.npl.co.uk

More articles from Physics and Astronomy:

nachricht Major discovery in controlling quantum states of single atoms
20.02.2018 | Institute for Basic Science

nachricht Observing and controlling ultrafast processes with attosecond resolution
20.02.2018 | Technische Universität München

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

'Lipid asymmetry' plays key role in activating immune cells

20.02.2018 | Life Sciences

MRI technique differentiates benign breast lesions from malignancies

20.02.2018 | Medical Engineering

Major discovery in controlling quantum states of single atoms

20.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>