суббота, 1 декабря 2018 г.

Launching Rockets from the Top of the World 🚀

Over the next 14 months, our scientists will join a group of

international researchers to explore a special region — Earth’s northern polar

cusp, one of just two places on our planet where particles from the Sun have

direct access to our atmosphere.


image

Earth is surrounded by a giant magnetic bubble known as a magnetosphere,

which protects our planet from the hot, electrically charged stream of

particles from the Sun known as the solar wind. The northern and southern polar

cusps are two holes in this protection — here, Earth’s magnetic field lines

funnel the solar wind downwards, concentrating its energy before injecting it

into Earth’s atmosphere, where it mixes and collides with particles of Earthly

origin.


image

The cusp is the only place where dayside auroras

are found — a special version of northern and southern lights, visible when the

Sun is out and formed by a different process than the more familiar nighttime

aurora. That’s what makes this region so interesting for scientists to study: The

more we learn about auroras, the more we understand about the fundamental

processes that drive near-Earth space — including those processes that disrupt

our technology and endanger our astronauts.


image


Photo credit: Violaene

Kaeser



The teams working on the Grand

Challenge Initiative — Cusp
will fly sounding rockets from two

Norwegian rocket ranges that fall under the cusp for a short time each day. Sounding

rockets
are sub-orbital rockets that shoot up into space for a few

minutes before falling back to Earth, giving them access to Earth’s atmosphere

between 30 and 800 miles above the surface. Cheaper and faster to develop than

large satellite missions, sounding rockets often carry the latest scientific

instruments on their first-ever flights, allowing for unmatched speed in the

turnaround from design to implementation.


image

Each sounding rocket mission will study a different aspect

of Earth’s upper atmosphere and its connection to the Sun and particles in

space. Here’s a look at the nine missions coming up.


1. VISIONS-2 (Visualizing

Ion Outflow via Neutral Atom Sensing-2) — December 2018


The cusp isn’t just the inroad into our atmosphere — it’s a

two-way street. Counteracting the influx of particles from the Sun is a process

called atmospheric escape, in which Earthly particles acquire enough energy to

escape into space. Of all

the particles that escape Earth’s atmosphere, there’s one that presents a

particular mystery: oxygen.


At 16 times the mass of hydrogen, oxygen should be too heavy

to escape Earth’s gravity. But scientists have found singly ionized oxygen in

near-Earth space, which suggests that it came from Earth. The two VISIONS-2 rockets,

led by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will create

maps of the oxygen outflow in the cusp, tracking where these heavy ions are and

how they’re moving to provide a hint at how they escape.


2. TRICE-2 (Twin

Rockets to Investigate Cusp Electrodynamics 2) — December 2018


If the cusp is like a funnel, then magnetic reconnection is

what turns on the faucet. When the solar wind collides with Earth’s magnetic

field, magnetic reconnection breaks open the previously closed magnetic field

lines, allowing some solar wind particles to stream into Earth’s atmosphere

through the cusp.


But researchers have noticed that the stream of particles

coming in isn’t smooth: instead, it has abrupt breaks in it. Is magnetic

reconnection turning on and off? Or is the solar wind shooting in from

different locations? TRICE-2, led by the University of Iowa in Iowa City, will

fly two separate rockets through a single magnetic field line in the cusp, to

help distinguish these possibilities. If reconnection sputters on and off over

time, then the two rockets should get quite different measurements, like noting

how it feels to run your finger back and forth under a faucet that is being

turned on and off. If instead reconnection happens consistently in multiple

locations — like having ten different faucets, all running constantly — then the

two rockets should have similar measurements whenever they pass through the

same locations.


image


Magnetic reconnection is a process by which magnetic field

lines explosively realign  



3. CAPER-2 (Cusp

Alfvén and Plasma Electrodynamics Rocket) — January 2019


The CAPER-2 rocket, led by Dartmouth College in Hanover, New

Hampshire, will examine how fast-moving electrons — particles that can trigger

aurora — get up to such high speeds. The team will zero in on the role that

Alfvén waves, a special kind of low-frequency wave that oscillates along

magnetic field lines, play in accelerating auroral electrons.


image


An illustration of rippling Alfvén waves



4. G-CHASER (Grand

Challenge Student Rocket) — January 2019


G-CHASER is made up entirely of student researchers from universities

in the United States, Norway and Japan, many of whom are flying their

experiments for the first time. The mission, led by the Colorado Space

Grant Consortium at the University of Colorado Boulder,

is a collaboration between seven different student-led missions,

providing a unique opportunity for students to design, test and ultimately fly

their experiment from start to finish. The students involved in the mission —

mostly undergraduates but including some graduate teams — are responsible for

all aspects of the mission, from developing the initial idea, to securing the

funding, to making sure it passes all the tests before flight.


5 & 6. AZURE (Auroral

Zone Upwelling Rocket Experiment) and CHI

(Cusp Heating Investigation) — April & November/December 2019


When the aurora shine, they don’t just emit light — they

also release thermal and kinetic energy into the atmosphere. Some of this

energy escapes back into space, but some of it stays with us. Which way this

balance tips depends, in part, on the winds in the cusp. AZURE, led by Clemson

University in South Carolina, will measure the vertical winds that swish energy

and particles around within the auroral oval, the larger ring around the pole

where the aurora are most common.


Later that year, the same team will launch the CHI mission, using a

methodology similar to AZURE to measure the flow of charged and neutral gases

inside the cusp. The goal is to better understand how particles, flowing in

horizontal and vertical directions, interact with each other to produce heating

and acceleration.


7. C-REX-2 (Cusp-Region

Experiment) — November 2019


The cusp is a place where strange physics happens, producing

some anomalies in the physical structure of the atmosphere that can make our

technology go haywire. For satellites that pass through the cusp, density

increases act like potholes, shaking up their orbits. Scientists don’t

currently understand what causes these density increases, but they have some

clues. C-REX-2, led by the University of Alaska Fairbanks, aims to figure out

which variables — wind, temperature or ion velocity — are responsible.


8. ICI-5

(Investigation of Cusp Irregularities-5) — December 2019


Recent research has uncovered mysterious hot patches of

turbulent plasma inside the auroral region that rain energetic particles

towards Earth. GPS signals become garbled as they pass through these turbulent

plasma patches, affecting so many of today’s technologies that depend on them. ICI-5,

led by the University of Oslo, will launch into the cusp to take measurements

from inside these hot patches. To measure their structure as several scales,

the rocket will eject 12 daughter payloads in concentric squares which will

achieve a variety of different separations.


image

9. JAXA’s SS-520-3

mission
— January 2020


Exploring the phenomenon of atmospheric escape, the Japan

Aerospace Exploration Agency’s SS-520-3 mission will fly 500 miles high over

the cusp to take measurements of the electrostatic waves that heat ions up and

get them moving fast enough to escape Earth.


For updates on the Grand Challenge Initiative and other

sounding rocket flights, visit nasa.gov/soundingrockets

or follow along with NASA Wallops and NASA heliophysics on Twitter and

Facebook.


@NASA_Wallops | NASA’s Wallops Flight

Facility
| @NASASun | NASA Sun

Science



Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


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