A rendering of China's XPNAV-1 satellite (CAST).

What China’s latest X-ray positioning satellite means for deep-space exploration

A rendering of China's XPNAV-1 satellite (CAST).

A rendering of China’s XPNAV-1 satellite (CAST).

On November 10, aboard a Long March 11 rocket, China launched a suite of satellites into space. Among them was the innovative X-ray Pulsar Navigation 1 (XPNAV 1) satellite which is equipped with a world’s first instrument that offers X-ray-based navigation. Unlike classical satellites and spacecraft that rely on GPS-like features, the XPNAV 1 uses X-ray sources from space like those emitted by pulsars to triangulate its position. In other words, this tiny satellite is paving the way for a new class of spacecraft that will not only breach the final frontier but also find its way around it.

To send spacecraft to Jupiter or land them on a comet, scientists require deep space navigation with incredible precision, as otherwise, the spacecraft would just crash in the first junk it encounters in space. To navigate these spacecraft, we generally set our own planet as a reference point. We know Earth’s  orbital parameters and inherent motions very well, so it’s just a matter of measuring the craft’s distance from Earth, the component of its velocity that is directly toward or away from Earth, and its position in Earth’s sky. These parameters are then converted to a sun-centric model.

This workflow has worked very well so far, but what happens if you want to exit the solar system? Because the craft is now many billions of miles away from Earth, it’s much harder to track and navigation can become increasingly skewed. As the craft gets farther and farther away from Earth, it will eventually travel in the dark.

The XPNAV 1 bypasses these limitations by reading deep space X-ray pulses given off by pulsars —  highly magnetized, rotating neutron stars. The pulsar rapidly rotates around its own axis producing X-ray pulses at short intervals. The way your phone uses GPS to find your location is it sends electromagnetic pulses to multiple satellites then, based on the response time, it triangulates the position. Similarly, XPNAV 1 reads various X-ray pulses of predictable nature and location to locate itself with an accuracy of 5 kilometers (3.1 miles). The error sounds like a lot (it really is too close for comfort) but scientists believe they can get more accurate positioning by finding pulsars with more consistent pulses.

NASA has it’s own X-ray pulsar navigation satellite too, the Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) mission. However, the satellite will launch in 2017 and China seems to have undercut NASA by a couple of months.

XPNAV 1 is innovative, a word you won’t normally use to describe something made in China, but that may soon change. China’s President Xi Jinping is betting on space big time and wants to triple government spending on scientific research. His hope is a new wave of innovations will come out of China, one that will inspire future generations and startups.

“China has been relying on the knowledge discovered by others,” said in a statement Wu Ji, director-general of the National Space Science Center, who’s spearheading the effort to lobby for more space missions with possible economic spinoffs. “If China wants to rejuvenate the economy, it needs to put more resources into developing groundbreaking technologies.”

As part of China’s ongoing five-year-plan, the nation hopes to produce 70 percent of key technology components—such as semiconductors and software— domestically by 2025.

Other major milestones for Chinese space exploration which happen this year include the launch of the Tiangong-2 space lab, the world’s first quantum science satellite and the debut of the new generation Long March 7 rocket.

3 thoughts on “What China’s latest X-ray positioning satellite means for deep-space exploration

  1. Pingback: What China’s latest X-ray positioning satellite means for deep-space exploration – ZME Science | List Author

  2. Godfree Roberts

    "XPNAV 1 is innovative, a word you won’t normally used to describe something made in China"?
    Tibi, if you want to continue writing about technology you'll need to learn Chinese. They already lead the world in Supercomputing, Speech Recognition, Graphenics, Thorium power, Pebble Bed Reactors, Genomics, Thermal Power generation, Quantum Communication Networks, ASW Missiles, In-Flight Satellite Refueling, Passive Array Radar, Metamaterials, Hyperspectral Imaging, Nanotechnology, UHV Electricity transmission, Electric Vehicles, High Speed Rail, Radiotelescopy, Hypersonic Space Weapons and Satellite Quantum Communications.
    With more to come…

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