redmoddata/lines_train_2M · Datasets at Hugging Face

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days of telescopic study of Mars, because it lies near the planet's meridian, or line of zero
longitude. "Planum" means plains, and the name fits: Meridiani Planum is one of the
smoothest, flattest places on Mars.
The scientific appeal of Meridiani comes not from its smooth landscape, but from its
strange mineral composition. Looking down from orbit, the thermal emission spectrometer
instrument on the Mars Global Surveyor spacecraft has shown that Meridiani Planum is
rich in an iron oxide mineral called gray hematite. Gray hematite is found on Earth, where
it usually -- though not always -- forms in association with liquid water.
Did the formation of the telltale mineral hematite at Meridiani involve liquid water? If it did,
what was the process? Was the water in a lake? Was it percolating through rocks, perhaps
at high tempera tures? Was it present only as a trace on the surfaces of rocks? If water
was present, were the conditions at Meridiani favorable for life? Or did the hematite form
by some other process that didn't involve water at all? And what other clues does Meridani
Planum hold regarding past conditions on Mars?
Rover A -- the first to launch and land -- will go to Gusev, while Rover B will go to Meridiani.
Landing sites
Mission Overview
NASA's Mars Exploration Rover Project will deliver two mobile laboratories to the sur-
face of Mars for robotic geological fieldwork, including the examination of rocks and
soils that may reveal a history of past water activity.
Sequences of launch, cruise and arrival operations will dispatch each rover to a differ-
ent area of the planet three weeks apart to explore those areas for about three months
The two identical rovers can recognize and maneuver around small obstacles on their
way to target rocks selected by scientists from images sent by the rovers. They will
conduct unprecedented studies of Mars geology, such as the first microscopic observa-
tions of rock samples. They will provide "ground truth" characterization of the landing
vicinities that will help to calibrate observations from instruments that view the planet
from above on Mars orbiters.
NASA selected the sites to be explored, Gusev Crater and Meridiani Planum, from 155
potential locations as the two offering the best combination of safe landing potential
and scientific appeal in assessing whether liquid water on Mars has ever made envi-
ronments conducive to life.
While the rovers and the instruments they carry are the centerpieces of the project,
each rover mission also depends on the performance of other components: the launch
vehicle; a cruise stage; a system for entering Mars' atmosphere, descending through it
and landing; a versatile system for deep-space communications; Earth facilities for
data processing; and an international team of engineers, scientists and others.
Launch Vehicle
The two rover spacecraft will be lofted on three-stage Delta II rockets from Florida's
Cape Canaveral Air Station. Rover A will launch on a version of the Delta II known as
model 7925, a vehicle with a history of more than 40 successful launches, including
those of the Mars Global Surveyor, Mars Pathfinder and Mars Odyssey missions.
Rover B will use a newer, slightly more powerful version called model 7925H; the H
identifies the vehicle as a heavy lifter.
Both of the Deltas feature a liquid-fueled first stage with nine strap-on solid-fuel boost-
ers; a second-stage liquid-fueled engine; and a third stage solid-fuel rocket. The differ-
ence between the two versions is in the size of the strap-on boosters. With their pay-
loads on top, each launch vehicle stands 39.6 meters (130 feet) tall.
The first stage of the Delta II uses a Rocketdyne RS-27A main engine. The engine pro-
vides nearly 890,000 newtons (200,000 pounds) of thrust by reacting RP-1 fuel (ther-
mally stable kerosene) with liquid oxygen. The nine boosters for the first rover mission
are 1,016 millimeters (40 inches) in diameter and fueled with enough hydroxyl-termi-
nated polybutadiene solid propellant to provide about 446,000 newtons (100,000
pounds) of thrust apiece. The nine for the second mission are each 1,168 millimeters
(46 inches) in diameter, with about 25 percent more thrust.
The Delta's second stage is powered by a restartable Aerojet AJ10-118K engine, which
produces about 44,000 newtons (9,900 pounds) of thrust. The engine uses a fuel
called Aerozine 50, which is a mixture of hydrazine and dimethyl hydrazine, reacted
with nitrogen tetroxide as an oxidizer.
A Star-48B solid-fuel rocket made by Thiokol powers the third stage. It adds a final kick
of about 66,000 newtons (14,850 pounds), using a propellant made primarily of ammo-
nium perchlorate and aluminum.
Launch Timing
Rover A will be launched between June 8 and June 24, 2003, followed by Rover B
between June 25 and July 15, 2003. To allow changeover of ground equipment at the
launch pads, the two missions must be launched at least 10 days apart, so if Rover A
launches at the end of its launch period Rover B's launch will be slipped accordingly.
Rover A will lift off from Cape Canaveral's Space Launch Complex 17A , while Rover B
will use the station's Space Launch Complex 17B.
Each mission has a total of two nearly instantaneous launch opportunities each day.
On the first day of Rover A's launch period, June 8, the first opportunity is at 2:05:55
p.m. Eastern Daylight Time. On the first day of Rover B's launch period, June 25, the
first opportunity is at 12:38:16 a.m. EDT. Opportunities for both missions occur a few
minutes earlier each day as the launch period progresses.
Launch Sequences
When each Delta II launches, its first-stage engine and six of its nine strap-on boosters
ignite at the moment of liftoff. The remaining three boosters will ignite following burnout
of the first six. The boosters' spent casings will be jettisoned in sets of three between 1
and 3 minutes after liftoff.
About 4 minutes and 23 seconds into the flight, the main engine will cut off. Within the
following 20 seconds, the first stage will separate from the second, the second stage
will ignite, and the nose cone, or "fairing," will fall away. At about 10 minutes after liftoff
for Rover A and 9 minutes after liftoff for Rover B, the second-stage engine will tem-
porarily stop firing.
At this point, the spacecraft with the second and third stages of the Delta still attached
will be in a circular parking orbit 167 kilometers (104 miles) above Earth. Before com-
Mars Exploration
Rover Spacecraft
Attach fitting
Spin table
Third-stage motor
separation clamp band
Guidance electronics
Second-stage miniskirt and support truss
Helium spheres
Nitrogen sphere
Wiring tunnel
Fuel tank
Centerbody section
First-stage oxidizer tank

days of telescopic study of Mars, because it lies near the planet's meridian, or line of zero

longitude. "Planum" means plains, and the name fits: Meridiani Planum is one of the

smoothest, flattest places on Mars.

The scientific appeal of Meridiani comes not from its smooth landscape, but from its

strange mineral composition. Looking down from orbit, the thermal emission spectrometer

instrument on the Mars Global Surveyor spacecraft has shown that Meridiani Planum is

rich in an iron oxide mineral called gray hematite. Gray hematite is found on Earth, where

it usually -- though not always -- forms in association with liquid water.

Did the formation of the telltale mineral hematite at Meridiani involve liquid water? If it did,

what was the process? Was the water in a lake? Was it percolating through rocks, perhaps

at high tempera tures? Was it present only as a trace on the surfaces of rocks? If water

was present, were the conditions at Meridiani favorable for life? Or did the hematite form

by some other process that didn't involve water at all? And what other clues does Meridani

Planum hold regarding past conditions on Mars?

Rover A -- the first to launch and land -- will go to Gusev, while Rover B will go to Meridiani.

Landing sites

Mission Overview

NASA's Mars Exploration Rover Project will deliver two mobile laboratories to the sur-

face of Mars for robotic geological fieldwork, including the examination of rocks and

soils that may reveal a history of past water activity.

Sequences of launch, cruise and arrival operations will dispatch each rover to a differ-

ent area of the planet three weeks apart to explore those areas for about three months

The two identical rovers can recognize and maneuver around small obstacles on their

way to target rocks selected by scientists from images sent by the rovers. They will

conduct unprecedented studies of Mars geology, such as the first microscopic observa-

tions of rock samples. They will provide "ground truth" characterization of the landing

vicinities that will help to calibrate observations from instruments that view the planet

from above on Mars orbiters.

NASA selected the sites to be explored, Gusev Crater and Meridiani Planum, from 155

potential locations as the two offering the best combination of safe landing potential

and scientific appeal in assessing whether liquid water on Mars has ever made envi-

ronments conducive to life.

While the rovers and the instruments they carry are the centerpieces of the project,

each rover mission also depends on the performance of other components: the launch

vehicle; a cruise stage; a system for entering Mars' atmosphere, descending through it

and landing; a versatile system for deep-space communications; Earth facilities for

data processing; and an international team of engineers, scientists and others.

Launch Vehicle

The two rover spacecraft will be lofted on three-stage Delta II rockets from Florida's

Cape Canaveral Air Station. Rover A will launch on a version of the Delta II known as

model 7925, a vehicle with a history of more than 40 successful launches, including

those of the Mars Global Surveyor, Mars Pathfinder and Mars Odyssey missions.

Rover B will use a newer, slightly more powerful version called model 7925H; the H

identifies the vehicle as a heavy lifter.

Both of the Deltas feature a liquid-fueled first stage with nine strap-on solid-fuel boost-

ers; a second-stage liquid-fueled engine; and a third stage solid-fuel rocket. The differ-

ence between the two versions is in the size of the strap-on boosters. With their pay-

loads on top, each launch vehicle stands 39.6 meters (130 feet) tall.

The first stage of the Delta II uses a Rocketdyne RS-27A main engine. The engine pro-

vides nearly 890,000 newtons (200,000 pounds) of thrust by reacting RP-1 fuel (ther-

mally stable kerosene) with liquid oxygen. The nine boosters for the first rover mission

are 1,016 millimeters (40 inches) in diameter and fueled with enough hydroxyl-termi-

nated polybutadiene solid propellant to provide about 446,000 newtons (100,000

pounds) of thrust apiece. The nine for the second mission are each 1,168 millimeters

(46 inches) in diameter, with about 25 percent more thrust.

The Delta's second stage is powered by a restartable Aerojet AJ10-118K engine, which

produces about 44,000 newtons (9,900 pounds) of thrust. The engine uses a fuel

called Aerozine 50, which is a mixture of hydrazine and dimethyl hydrazine, reacted

with nitrogen tetroxide as an oxidizer.

A Star-48B solid-fuel rocket made by Thiokol powers the third stage. It adds a final kick

of about 66,000 newtons (14,850 pounds), using a propellant made primarily of ammo-

nium perchlorate and aluminum.

Launch Timing

Rover A will be launched between June 8 and June 24, 2003, followed by Rover B

between June 25 and July 15, 2003. To allow changeover of ground equipment at the

launch pads, the two missions must be launched at least 10 days apart, so if Rover A

launches at the end of its launch period Rover B's launch will be slipped accordingly.

Rover A will lift off from Cape Canaveral's Space Launch Complex 17A , while Rover B

will use the station's Space Launch Complex 17B.

Each mission has a total of two nearly instantaneous launch opportunities each day.

On the first day of Rover A's launch period, June 8, the first opportunity is at 2:05:55

p.m. Eastern Daylight Time. On the first day of Rover B's launch period, June 25, the

first opportunity is at 12:38:16 a.m. EDT. Opportunities for both missions occur a few

minutes earlier each day as the launch period progresses.

Launch Sequences

When each Delta II launches, its first-stage engine and six of its nine strap-on boosters

ignite at the moment of liftoff. The remaining three boosters will ignite following burnout

of the first six. The boosters' spent casings will be jettisoned in sets of three between 1

and 3 minutes after liftoff.

About 4 minutes and 23 seconds into the flight, the main engine will cut off. Within the

following 20 seconds, the first stage will separate from the second, the second stage

will ignite, and the nose cone, or "fairing," will fall away. At about 10 minutes after liftoff

for Rover A and 9 minutes after liftoff for Rover B, the second-stage engine will tem-

porarily stop firing.

At this point, the spacecraft with the second and third stages of the Delta still attached

will be in a circular parking orbit 167 kilometers (104 miles) above Earth. Before com-

Mars Exploration

Rover Spacecraft

Attach fitting

Spin table

Third-stage motor

separation clamp band

Guidance electronics

Second-stage miniskirt and support truss

Helium spheres

Nitrogen sphere

Wiring tunnel

Fuel tank

Centerbody section

First-stage oxidizer tank