Neutron star mission.
British scientist Jocelyn Bell discovered the existence of rapidly spinning neutrons stars,
about 50 years ago.
NASA has launched the first mission, devoted to studying these objects.
It is called the Neutron Star Interior Composition Explorer, or NICER.
The mission will also carry out the world’s first demonstration, of X-ray navigation in space.
It will be in spaceX, CRS-11, launched from a Falcon-9 rocket.
It will observe neutron stars, which are the densest objects in the Universe.
The mission will focus on pulsars.
Pulsars are neutron stars, which because of their spin, sweeps beams of radiation,
past us, like a cosmic light house.
Neutrons stars was theoretically proposed in 1939, and discovered in 1967.
These objects are remnants of massive stars, that after exhausting their nuclear fuel,
exploded and collapsed into super dense spheres, about the size of New York city.
There intense gravity crushes enormous amount of matter,
often more than 1.4 times the Sun, or about 460,000 Earths, into city sized orbs.
They have incredibly dense matter.
Just one teaspoon of neutron star matter, would weigh a billion tons on Earth.
The nature of matter under these conditions, is a unresolved problem.
There are a number of theories to describe,
the physics governing the interiors of neutron stars.
NICER will test these theories.
Neutron stars emit radiation across the spectrum.
Observing them in the energetic X-ray band offers the greatest insights, into their structure,
and the high energy phenomena that they host, including starquakes, thermonuclear
explosions, and the most powerful magnetic fields known in the cosmos.
NICER will collect X-rays generated from the neutron stars’ strong magnetic fields,
from hotspots located at their two magnetic poles.
At these locations, the stars’ intense magnetic fields emerge from their surfaces,
and particles trapped, within these fields rain down, and generate X-rays when they strike the stars’ surfaces.
In pulsars the flowing particles emit powerful beams of radiation from the magnetic poles.
On Earth these beams are observed as flashes of radiation,
ranging from seconds to milliseconds, depending on how fast the pulsar rotates.
Because these pulsations are predictable, they can be used as celestial clocks,
providing high precision timing, like the atomic clock signals supplied through GPS.
Although ubiquitous on Earth, GPS signals weaken the further one travels beyond Earth.
Pulsar, however are accessible virtually anywhere in space.
This makes them a valuable navigational solution, for deep space exploration.
The NICER mission plans to demonstrates the viability of X-ray or pulsar based navigation.
NICER telescopes detect X-rays emitted from the pulsars sweeping beam of radiation,
to estimate the arrival time of pulses.
With these measurements specially developed algorithms,
will formulate an onboard navigational solution.
If an interplanetary mission is equipped with such a navigational device,
it would be able to calculate its location autonomously.
This will make it largely independent of NASA’s Deep Space Network, which is considered to be most sensitive telecommunication system in the World.
The mission also intends to demonstrate X-ray based communications, or XCOM.
Such a capability could eventually allow space travellers, including spacecraft,
to transmit gigabits of data over interplanetary distances.
A device called MXS has been developed to calibrate the payload’s detectors,
and help test the algorithms to demonstrate X-ray navigation.
The device generates X-rays with rapidly varying intensity, turning on and off,
many times per second to stimulate, a neutron star’s pulsations.
MXS will be flown to the international space station, and deployed on a external pallet,
about 166 feet away from NICER.
It will encode digital data in pulsed X-rays using MXS,
and transmit the data to NICER’s receivers.
If the experiment is successful it promises giga bit per second data transmission speeds,
across vast distances.
It would also enable communication with hypersonic vehicles and spacecraft.