[meteorite-list] ESA Celebrates ExoMars Orbiter Success, Keeps Vigil For Lost Lander

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 21 Oct 2016 15:58:39 -0700 (PDT)
Message-ID: <201610212258.u9LMwdjd006909_at_zagami.jpl.nasa.gov>


ESA celebrates ExoMars orbiter success, keeps vigil for lost lander
Stephen Clark
SpaceFlight Now
October 19, 2016

A European-built orbiter designed to seek out the source of methane on
Mars slipped into orbit around the red planet Wednesday after a
seven-month interplanetary journey, but mission control lost contact
with an experimental landing probe just before touchdown.

Both spacecraft - part of the joint European-Russian ExoMars program -
reached Mars around the same time Wednesday for simultaneous maneuvers
to swing into orbit and plunge into the red planet's atmosphere.

The Schiaparelli lander, shaped like a flying saucer with a diameter of
nearly 8 feet (2.4 meters), dived into the Martian atmosphere as
expected around 1442 GMT (10:42 a.m. EDT) Wednesday.

Designed for a technology demonstration mission, Schiaparelli had heat
shield tiles, a parachute and nine rocket thrusters to slow its speed
from 13,000 mph (21,000 kilometers per hour) to zero in less than six

But something went wrong in the last phase of the descent, interrupting
a real-time beacon signal sent back to Earth to a vast radio telescope
array in Pune, India. The carrier tone went silent after mission
controllers reported Schiaparelli's supersonic parachute had deployed,
but the signal only told engineers whether the spacecraft was
transmitting, and did not contain telemetry data that might reveal the
root of the problem.

European Space Agency officials waited to receive a recording of
Schiaparelli's beacon signal from the Mars Express orbiter around the
red planet to confirm some sort of glitch with the Indian antennas was
not responsible for the loss of communications.

"We saw the signal through the atmospheric phase - the descent phase. At
a certain point, it stopped," said Paolo Ferri, head of ESA's mission
operations department. "This was unexpected, but we couldn't conclude
anything from that because this very weak signal picked up on the ground
was coming from an experimental tool."

The telescope array in India was never designed to communicate with deep
space missions like Schiaparelli, but engineers added equipment to the
antenna network - the largest in the world - for Wednesday's Mars
landing in hopes of gaining real-time insight into the status of the

Otherwise, ground controllers would have had to wait for Mars Express
for news on the 1,272-pound (577-kilogram) landing craft.

It turns out the ground team at the European Space Operations Center in
Darmstadt, Germany, had to wait all day Wednesday as data on
Schiaparelli's landing trickled back to Earth and hopes for the
mission's successful landing waned.

The carrier signal from Schiaparelli relayed by Mars Express also
abruptly ended shortly before landing, just as the beacon tone received
in India.

"The Mars Express measurement came - and confirmed exactly the same: the
signal went through the majority of the descent phase, and it stopped at
a certain point that we reckon was before the landing," Ferri said.

"There could be many many reasons for that," Ferri said. "It's clear
these are not good signs, but we will need more information."

The newly-arrived Trace Gas Orbiter, Schiaparelli's mothership, recorded
detailed telemetry broadcast by the lander - not just the beacon signal
- and that data should be beamed back to Earth overnight, according to

"This is fundamental because we should remember that this landing was a
test, and as part of the test, you want to know what happened," Ferri said.

"If the landing were to fail, presumably from TGO we will know what was
the last thing that worked all right," said Jorge Vago, ESA's ExoMars
project scientist, in an interview with Spaceflight Now on Tuesday,
before Schiaparelli's landing attempt.

Officials hope to share more on what they know about Schiaparelli's fate
in a press conference Thursday at 0800 GMT (4 a.m. EDT).

Schiaparelli rode to Mars piggyback on the Trace Gas Orbiter after their
tandem launch March 14 aboard a Russian Proton rocket, then separated
Sunday for the final approach to the planet.

Both ExoMars spacecraft were manufactured by an industrial team led by
Thales Alenia Space.

The orbiter fired its main engine at 1305 GMT (9:05 a.m. EDT), smoothly
slowing the craft's velocity by more than 3,300 mph (1.5 kilometers per
second) during a 139-minute burn.

The final few minutes of the make-or-break rocket maneuver occurred as
the spacecraft flew behind Mars, temporarily cutting off communications.
When mission control regained contact with the Trace Gas Orbiter,
telemetry showed the probe was healthy and had completed the orbit
insertion burn as planned.

The confirmation sparked a round of applause inside the ExoMars control
center, but attention quickly turned back to Schiaparelli.

"Part of the mission is a clear go," said Don McCoy, ESA's ExoMars
project manager, after the Trace Gas Orbiter braked into orbit around
Mars without difficulty. "For the lander, we have received some data -
We've seen a series of indicators of the entry, parachute deployment,
release of the backshell, etc. We don't have the full set of data."

The orbiter is the primary part of the mission, carrying four science
instruments to take pictures, locate water resources, and search for the
sources of intermittent methane detected in the Martian atmosphere, an
indicator of ongoing biological or geological activity.

ESA expects the Trace Gas Orbiter to function through at least 2022 and
help relay commands and science data between Earth and a fleet of
existing and planned rovers on the Martian surface.

NASA provided two radio packages for the orbiter to link up with the
Curiosity and Opportunity rovers, along with planned rovers from NASA
and ESA scheduled for launch in 2020.

Officials billed Schiaparelli as a technology demonstrator, and the
probe was aiming to become the first European spacecraft to successfully
land and function on Mars.

Engineers hoped lessons learned from Schiaparelli will feed into the
design of the second part of the two-launch ExoMars program, a
European-built rover scheduled for liftoff in mid-2020.

Under the terms of their partnership with ESA, Russian engineers will
design and build the descent module for the ExoMars rover, but the
computer and parts of the lander's guidance system will come from
Europe. Schiaparelli was supposed to verify parts of the design worked
at Mars.

A doppler radar altimeter was supposed to activate when Schiaparelli
jettisoned its forward heat shield under parachute and collect data on
the spacecraft's altitude and speed. The measurements were to go to
Schiaparelli on-board computer to control the thrust of nine
hydrazine-fueled rocket engines fixed around the perimeter of the probe.

The thrusters were programmed to cut off around 6 feet, or 2 meters,
above the Martian surface, and Schiaparelli was to fall to the ground
cushioned by a crushable carbon-fiber crash structure.

A downward-facing descent camera was expected to take images during the
last phase of Schiaparelli's descent, and the lander's computer was
supposed to switch on a weather station after touchdown to monitor the
temperature, humidity, pressure, dust opacity, wind speed, and wind
direction at site landing site in Meridiani Planum, a relatively flat
plain near the Martian equator.

Named for Italian astronomer Giovanni Schiaparelli, the lander was to
become the first mission to land on Mars during the planet's global dust
storm season. One of the sensors aboard the craft was designed to
measure electrical fields in the Martian atmosphere, one of the
mechanisms scientists think might drive dust storms.

"The Schiaparelli lander was designed to be able to land in a global
dust storm, a big one where you don't see anything," Vago said. "From
the point-of-view of hypersonic entry, heat shield performance, and
parachute performance, it should all be OK."

The lander, primarily funded and built in Italy, was also fitted with
instrumentation to track the density, pressure and temperature of the
atmosphere from the point of entry at an altitude of 80 miles (130
kilometers) to the surface. Another payload on Schiaparelli was a
compact array of laser retroreflectors to help future orbiters precisely
locate the lander.

Schiaparelli only carried batteries to power its science sensors,
computer and radio transmitter, so engineers expected it to shut down
within a few days of landing.

ESA said ground controllers will have multiple opportunities in the
comings to attempt to contact Schiaparelli - assuming it is safely on
the surface - before its batteries run down.

"We don't know all the details (about Schiaparelli's status), but this
is typical for a test," said Jan Woerner, ESA's director general. "We
did this in order to get data about how to land European technology on
Mars, therefore, all the data we will get tonight - will be used to
understand how to manage the next landing when we will go with a
European rover."

Wednesday's nail-biting landing attempt came 13 years after the Beagle 2
probe built in Britain reached the red planet.

Mission control never heard from Beagle 2 after its landing attempt, but
scientists last year revealed new imagery from Mars orbit apparently
showing the lander sitting the surface with its power-generating solar
arrays still partially folded.

The discovery led engineers to conclude Beagle 2 may have survived its
landing, but a problem prevented full deployment of the solar panels,
potentially blocking the antenna that was to radio its status to Earth.

Schiaparelli's flight to Mars was Europe's second try, with a much
bigger package than Beagle 2. It went to Mars with the new doppler radar
guidance system, modernized control algorithms and a computer that will
be crucial to the 2020 mission's rover landing.

The ExoMars Trace Gas Orbiter is ESA's second spacecraft circling the
red planet after Mars Express, which is still flying well beyond its
design life after arriving at Mars in 2003.

With the insertion of the latest orbiter, there are now six active
satellites around Mars, including the two ESA science stations, three
NASA orbiters, and an Indian spacecraft.

Navigators intended for the Trace Gas Orbiter to enter into an initial
egg-shaped orbit taking the spacecraft as close as 186 miles (300
kilometers) and as far as 60,000 miles (96,000 kilometers) from Mars.

Experts verified the orbiter was right on course after its orbit
insertion burn.

"Yes, the TGO is captured in orbit around Mars, and yes, it's in a very
nominal orbit of four days duration, only a couple hours more, but this
is within a few percent, and it's perfectly normal," said Michel Denis,
ExoMars flight director.

All systems on the orbiter are performing well, he said.

"It's all good," Denis said. "It's a good spacecraft at the right place,
and we have a mission around Mars, another one."

The orbiter will turn on its camera and science instruments for two
orbits - about eight days - in November for a first look at the red
planet since arriving, according to Vago.

"We will turn the instruments on and hope to be able to make some
interesting first observations then," Vago said. "Don't expect any
magnificent revelations on the distribution of methane or trace gases
just in two orbits, but some images for sure and the confirmation that
the instruments work as well."

Starting in January, the orbiter will begin an aerobraking campaign,
dipping into the upper fringes of Mars' atmosphere on each lap around
the planet. Drag on the spacecraft's solar panels will gradually lower
its altitude, with the satellite ending up in a circular 250-mile-high
(400 kilometer) orbit by early 2018.
Received on Fri 21 Oct 2016 06:58:39 PM PDT

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