Tag Archives: interstellar travel

Scientists demonstrate first space navigation on ISS using pulsars

The stars are ours! Scientists using an x-ray telescope installed on ISS have demonstrated it is possible to pinpoint the location of a spaceship and thus navigate through space using pulsars.

In the SEXTANT demonstration that occurred over the Veteran’s Day holiday in 2017, the SEXTANT team selected four millisecond pulsar targets — J0218+4232, B1821-24, J0030+0451, and J0437-4715 — and directed NICER to orient itself so it could detect X-rays within their sweeping beams of light. The millisecond pulsars used by SEXTANT are so stable that their pulse arrival times can be predicted to accuracies of microseconds for years into the future.

During the two-day experiment, the payload generated 78 measurements to get timing data, which the SEXTANT experiment fed into its specially developed onboard algorithms to autonomously stitch together a navigational solution that revealed the location of NICER in its orbit around Earth as a space station payload. The team compared that solution against location data gathered by NICER’s onboard GPS receiver. “For the onboard measurements to be meaningful, we needed to develop a model that predicted the arrival times using ground-based observations provided by our collaborators at radio telescopes around the world,” said Paul Ray, a SEXTANT co-investigator with the U. S. Naval Research Laboratory. “The difference between the measurement and the model prediction is what gives us our navigation information.”

The goal was to demonstrate that the system could locate NICER within a 10-mile radius as the space station sped around Earth at slightly more than 17,500 mph. Within eight hours of starting the experiment on November 9, the system converged on a location within the targeted range of 10 miles and remained well below that threshold for the rest of the experiment, Mitchell said. In fact, “a good portion” of the data showed positions that were accurate to within three miles. “This was much faster than the two weeks we allotted for the experiment,” said SEXTANT System Architect Luke Winternitz, who works at Goddard. “We had indications that our system would work, but the weekend experiment finally demonstrated the system’s ability to work autonomously.”

I think everyone who is interested in interstellar space travel has assumed since the discovery of the first pulsars that they would end up serving as the future north star for interstellar travelers. This experiment shows us how it will be done.

Well read science fiction fans should recognized the literary reference in the tagline.


Russian billionaire backs interstellar project

The competition heats up: A Russian billionaire has announced a $100 million investment in an effort to use lasers to propel cellphone-sized spacecraft on an interstellar voyage to Alpha Centauri.

Called Breakthrough Starshot, the programme is based on an idea that has been around for decades: the solar sail. The theory is that a lightweight space sail could harness the momentum carried by photons in order to travel without fuel.

The Breakthrough Starshot team is betting that a burst of concentrated lasers, fired from the ground, could rapidly accelerate a mobile-phone-sized device equipped with microelectronics and a tiny sail — providing much more energy than could be harnessed from the Sun. Whereas NASA’s plutonium-powered New Horizons spacecraft took nine years to reach Pluto, the “nanocraft” envisioned by Breakthrough Starshot would pass by the dwarf planet and exit the Solar System in three days.

The project’s initial US$100-million budget covers only research and development of such a spacecraft. But Breakthrough Starshot’s ultimate goal is to demonstrate proof of concept for an international programme that would send a fleet of nanocraft into space. Doing so would require the group to surmount enormous scientific and engineering challenges in developing the necessary laser technology, materials and communications systems.

This technology is related though not identical to an earlier story about using lasers to power spacecraft.