Wednesday, July 8, 2015

New Horizons Back on Track for Pluto Flyby

WASHINGTON — NASA’s New Horizons spacecraft has exited a protective safe mode that project officials said July 6 was triggered when the spacecraft’s primary computer became overloaded.
New Horizons, which entered safe mode July 4, briefly cutting off communications with the Earth, will resume normal science observations on July 7, and the project’s leadership said they remain confident the spacecraft will operate normally through its July 14 flyby of Pluto.
“The spacecraft is in excellent health and is back in operation,” said Jim Green, director of NASA’s planetary science division, during a conference call with reporters July 6.
The problem took place, said Glen Fountain, New Horizons project manager at Johns Hopkins University Applied Physics Laboratory, because the spacecraft’s primary computer was doing too much at one time. Ground controllers were transmitting a set of commands to the spacecraft, called a “command load,” that it will carry out during the flyby. At the same time, the computer was compressing data stored from previous observations that controllers did not plan to immediately transmit back to Earth, freeing up memory to store new data.
“So we were doing multiple things on the processor on the spacecraft at the same time,” he said. The combination of compressing data and storing the command load was too much for the computer. “The computer was trying to do these two things at the same time, and the two were more than the processor could handle at one time.”
The spacecraft, Fountain said, worked exactly as planned, switching to its backup computer and going into safe mode. The backup computer started transmitting on schedule, allowing engineers on the ground to quickly diagnose the problem. “We realized what was happening,” he said, “and we put a plan in place to recover.”
The spacecraft exited safe mode on July 5, but the project team decided to hold off on resuming science observations until July 7, when the spacecraft will begin carrying out the uploaded series of commands for Pluto flyby. That sequence of commands runs through July 16, two days after the spacecraft’s closest approach to Pluto.
“That was a command decision which I made, and which the team was in complete agreement with, at the beginning of the recovery operation,” said Alan Stern, New Horizons principal investigator, on the decision to wait until July 7 to resume collecting science data. “It’s much more important to focus on getting ready for the flyby than to collect science eight or nine million miles from the target.”
That decision means losing about 30 observations planned between the time of the computer malfunction July 4 and when the spacecraft starts executing the new sequence of commands July 7. That includes 16 images by the spacecraft’s Long Range Reconnaissance Imager camera and four color images by another camera known as Ralph.
Those lost observations, Stern said, account for about six percent of the overall observations New Horizons planned to take between July 4 and 16. However, he added that since the observations were taken while the spacecraft was still millions of kilometers away, they were less significant scientifically.
“Our assessment is that the weighted loss is far less than one percent,” he said. “We can say there is zero impact to the ‘Group One,’ or highest priority science.” Stern characterized the overall science lost because of the computer problem as a “speed bump in terms of the total return that we expect from this flyby.”
Fountain said the specific problem that caused this safe mode won’t happen again: there are no plans to simultaneously upload commands and compress data through the July 14 flyby. “I’m quite confident that this kind of event will not happen,” he said.
The spacecraft will also execute the series of commands for the flyby in what Fountain called “encounter mode,” so that any problems like the one July 4 will not cause a safe mode. Instead, the computer will request help from ground controllers while continuing to carry out commands. Controllers can also send what he called a “slam” command to the spacecraft, forcing the computer to return to the series of commands in its memory for the flyby.
Stern said the spacecraft’s encounter mode has been tested several times earlier in the mission in preparation for the flyby, including a full nine-day rehearsal in 2013. “I’m not worried at all about going into encounter mode tomorrow,” he said.

Mars Rover Curiosity Dealing with Wheel Damage

NASA’s Mars rover Curiosity faces ongoing wheel wear and tear as it continues its trek across the rock-strewn red planet.

The car-size Curiosity rover has been on duty since landing on Mars in August 2012. Curiosity has six aluminum wheels, each with its own individual motor. The rover has a top speed on flat, hard ground of a little over 4 centimeters per second.

But dealing with the rocky Martian landscape has become somewhat of an unanticipated wheel of misfortune for the Curiosity crew. Back here on Earth, mission engineers are watching the wheels turn, keeping an eye on the dings and cracks that have begun to appear.

Grousing About Grousers

“The bottom line is that we are monitoring the wheels all the time,” said Jim Erickson, Curiosity project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.

Each of Curiosity’s wheels is about 50 centimeters in diameter and 40 centimeters wide. The wheels have so-called grousers that form something akin to a tread pattern. The skin of a rover wheel is just 0.75 millimeters thick, with the protruding grousers providing structural strength.

Erickson said that, to date, no grouser has been broken — and that’s a good thing. “You can break one. It looks bad, but not horrible. We aren’t there yet,” he said.

Special wheel tests have been performed at JPL. Even with two-thirds of the inner part of the wheel gone, driving on that outer one-third of the wheel appears doable, Erickson said.

Uncertain Wheel Life

Curiosity’s two front wheels began accumulating damage early in the mission.That wear and tear continues, and now the rover’s two middle wheels are showing major damage, Erickson said.

But “the rear wheels are still almost pristine,” he said.

To help cope with the wheel situation, Curiosity engineers are looking at software changes on the vehicle, “to try and make things a little bit better,” Erickson said. “They’ve had some good tests, but it’s not ready for prime time yet.”

The software could provide situational awareness to the wheels, Erickson said, matching wheel drive with electrical current, depending on what terrain the rover faces.

There remain uncertainties about how much overall wheel life is left on Curiosity, Erickson said. One helpful remedy is to carefully guide the robot through less-damaging terrain, he said.

Right Balance

Team members spend significant amounts of time planning out Curiosity’s routes, particularly making use of NASA’s Mars Reconnaissance Orbiter and its high-resolution imaging science experiment (HiRISE) camera system.

Finding the right balance between wheel protection and data collection is also on the mind of Curiosity project scientist Ashwin Vasavada, also of JPL.

“Curiosity’s engineering and science teams have spent over a year understanding how the rover’s design and driving algorithms — and Mars’ terrain — led to more wheel damage than was expected,” Vasavada said. “We’ve also developed a wheel test bed to better predict how the wheels will degrade over time, under certain conditions.”

In addition, Vasavada said that Curiosity teams have mapped out a network of routes up Mount Sharp — the 5.5 kilometer mountain whose foothills the rover is exploring — that vary in their scientific value and also in risk to the robot’s wheels.

“This allows the project as a whole to find the right balance between our scientific progress and factors like wheel wear, slopes and navigability,” Vasavada said. “It all looks quite optimistic and manageable at this point.”

Erickson agrees.

From all of the simulation testing, “the wheel assessment is that we haven’t used up 50 percent of the wheels as yet … and we’ve been driving for three years. I guess I’m neither optimistic nor pessimistic,” Erickson said. “I am more resigned to the fact that we have a consumable.”

Thursday, June 25, 2015

PlanetiQ Selects Blue Canyon Technologies For Smallsat Constellation

WASHINGTON — PlanetiQ announced June 24 that it has selected a Colorado company to build its planned constellation of small satellites to provide weather data, with the first satellites to be launched in late 2016.

Bethesda, Maryland-based PlanetiQ said Blue Canyon Technologies of Boulder, Colorado, will build a set of 12 satellites, each carrying a Global Positioning System radio occultation payload. The companies did not disclose the value of the contract.

The satellites, PlanetiQ President and Chief Executive Anne Hale Miglarese said in an interview, will be six-unit cubesats with on-board propulsion, each weighing less than 20 kilograms. The satellites will operate in orbits of 750 to 800 kilometers at an inclination of 72 degrees.

The current spacecraft design is considerably smaller than the company’s original concepts, which weighed in at more than 120 kilograms. “We’ve been through many iterations on this spacecraft,” Miglarese said. “We are very confident that we have the right spacecraft.”

The decrease in size does not affect the quality of the data collected, she said. The company has been separately developing its GPS radio occultation sensor, called Pyxis, that measures signals from GPS and other navigation satellites as those signals pass through the atmosphere. Those measurements provide soundings of the atmosphere that can be fed into weather forecasting models.

One tradeoff that PlanetiQ did have to make by moving to the smaller satellite is the elimination of a real-time data relay system in at least the first six satellites. “That was very power hungry, and made us heavy,” she said. Instead, the satellites will use a network of ground stations, which should delay the receipt of data by no more than 90 minutes.

Miglarese said PlanetiQ selected Blue Canyon Technologies based on its experience with a number of U.S. government programs. The company is primarily known for providing components for small satellites, but also develops cubesat-class spacecraft. In April, it won a contract to build the Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) small satellite for the Applied Physics Laboratory of Johns Hopkins University.

“We’re excited to have Blue Canyon Technologies as a partner,” Miglarese said. She added that PlanetiQ will co-locate its engineering staff at Blue Canyon’s Colorado facilities during spacecraft development, while maintaining a headquarters office in Maryland.

PlanetiQ plans to launch its first two satellites in the fall of 2016, with the remaining ten to launch in the first half of 2017. Those satellites will be launched as secondary payloads, which the company is in the process of negotiating, she said.

PlanetiQ is one of several companies and government agencies planning satellite constellations to provide GPS radio occultation data. Two other companies, GeoOptics and Spire, are actively developing satellite systems, with Spire planning to launch 20 cubesats by the end of the year for a system that will eventually comprise 125 satellites. The United States and Taiwan are also working on the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) 2 system of 12 satellites planned for launch in 2016 and 2018.

Miglarese said PlanetiQ’s sensor has the same heritage as the one planned for COSMIC-2. However, that sensor will be able to detect signals from all four current or planned global navigation satellite systems — GPS, GLONASS, Galileo and Beidou — allowing it to detect twice the number of occultations per day as COSMIC-2. The PlanetiQ sensors should also have better performance than commercial competitors, she added.

The company’s business case is focused in part on selling data to commercial weather forecasting firms. “There are seven to eight companies internationally that do numerical weather prediction” and could make use of GPS radio occultation data to refine their models, she said.

Miglarese said the company also plans to sell data to governments, and is closely following the development of commercial weather data policies at agencies like the National Oceanic and Atmospheric Administration. “We look to serve the U.S. government where we can,” she said.

Sunday, June 21, 2015

House, Senate Bills Deny Funds for Landsat Backup Capability

WASHINGTON — NASA should focus on building the next full-scale Earth-observing satellite in its long-running Landsat series and forget about a proposed interim capability to ensure continuous coverage in the infrared bands, House and Senate lawmakers said in separate 2016 spending bills drafted in June. To different degrees, the House and Senate Appropriations committees backed NASA’s plan to build Landsat 9, which would be a rough copy of the visible- and infrared-imaging Landsat 8 craft that launched in 2013. But both committees were in lockstep in directing the agency to scrap plans for a $180 million infrared-only backup satellite called the Thermal Infrared Free Flyer (TIR-FF) that would launch in 2019. The White House is seeking a combined $80 million next year for Landsat 9 and TIR-FF. A House spending bill passed June 3 would provide only about $33 million, specifically for Landsat 9, while a bill approved June 11 by the Senate Appropriations Committee provides $100 million with instructions to accelerate that satellite, now scheduled to launch in 2023.

 Landsat satellites collect medium-resolution Earth images as part of an unbroken record that dates back 43 years. Under the current program model, NASA builds and launches the satellites while the U.S. Geological Survey is responsible for operations and data distribution. In April, Michael Freilich, NASA’s Earth science director, told SpaceNews the agency conceived the TIR-FF mission because Landsat 8’s thermal-infrared instrument, a late addition to the program, is not performing to specifications and was in any case designed to work only for three years. Although Landsat 7 has a thermal imaging capability, that satellite is 16 years old and is likely to be shut down in 2019, he said. Landsat 8 was originally designed as a bare-bones Landsat 7 replacement that lacked a thermal-infrared imaging capability. But Congress, under pressure from western U.S. states to continue making thermal-infrared measurements for water resource management, directed NASA to add that capability to the satellite at a relatively late stage of the program. Freilich said NASA, in order to keep the satellite on schedule, did not build the usual longevity into the sensor. In addition to providing a backup thermal-infrared imaging capability, TIR-FF, in combination with the European Sentinel 2A Earth observing satellite slated to launch June 23, would effectively replace the full capability of Landsat 8 should it fail prematurely. But the Senate Appropriations Committee, which like its House counterpart is abiding strictly by spending caps set in the Budget Control Act of 2011, said the best risk insurance is Landsat 9. Accordingly, the Senate lawmakers provided no funding for TIR-FF and directed the agency instead to accelerate the Landsat 9’s launch by three years, to 2020. The House bill similarly denied funding for the free flyer and requested a report from NASA on the cost and milestones toward launching Landsat 7 “no later than 2023.” It is not clear whether the House and Senate will have a chance to reconcile their proposed 2016 budget bills. The Senate’s Democratic minority is threatening to block consideration of spending bills on the floor of that chamber. Samuel Goward, a professor at the University of Maryland in College Park and former principal investigator on Landsat 7, questioned why NASA is pursuing TIR-FF in the first place when it faces the larger problem of having only one fully capable Landsat satellite on orbit. A single Landsat satellite provides repeat coverage on 16-day cycles, but NASA has long been able to maintain at least two on orbit, and users have grown accustomed to the resulting eight-day repeat cycle. “If you’re going to do a free flyer with the Thermal Infrared Sensor onboard, why not put an optical component on the same system?” Goward said in a June 17 interview. “That’s a pretty low-cost solution, or it should be.” But Goward acknowledged that if Congress is unwilling to fund TIR-FF on budget grounds, it is unlikely to support building another full-scale Landsat satellite to accompany Landsat 9 on orbit. NASA spokesman Steve Cole did not immediately reply to a request for comment June 17. NASA stood up a Landsat 9 program office in April at the Goddard Space Flight Center in Greenbelt, Maryland, which will build the spacecraft’s thermal-infrared camera, as it did for Landsat 8. Other procurement decisions are pending. NASA hopes to finalize an acquisition strategy by Sept. 30, Freilich said. Ball Aerospace & Technologies Corp. of Boulder, Colorado, built Landsat 8’s main visible-spectrum camera, the Operational Land Imager, while Orbital ATK of Dulles, Virginia, provided the spacecraft bus. 

Airbus Faces Costly Delays on European Data Relay System

LE BOURGET, France — A European government-industry partnership using space-based lasers to speed data between Earth observation satellites and the ground using geostationary satellites as relay towers is facing potentially costly delays for industrial contractor Airbus Defence and Space. Already slowed by differences between the two government sponsors — the European Space Agency and the European Commission — the European Data Relay System (EDRS) is now stalled by what may be a months-long delay in the launch of its first geostationary payload. Airbus, which said it has invested more than 130 million euros (148 million) in securing two EDRS geostationary payloads and their launch, is basing its initial EDRS service on laser communications terminals on two geostationary satellites. 
The first, called EDRS-A, is a hosted payload aboard Paris-based Eutelsat’s Eutelsat 9B satellite. It is this satellite that will debut EDRS commercial service and the start of funding from the European Commission, EDRS’s anchor customer. The commission owns the European Space Agency-developed Sentinel Earth observation satellites, two sets of which carry laser terminals to relay their data to the geostationary platforms. Sentinel 1A is already in orbit, and Sentinel 2A is scheduled for launch on June 23. Identical copies of both satellites are under construction, and all will carry laser terminals to deliver data at speeds of up to 1.8 gigabits per second to the geostationary satellites. Airbus had hoped that 2015 would be the breakout year for EDRS, with the start of commercial services that would coax potential future customers into service commitments. That now looks less likely. Eutelsat 9B is one of several commercial satellites awaiting a return to flight of Russia’s Proton rocket following the vehicle’s failure in May. Eutelsat has said it expects the Russian government commission investigating the May failure to deliver its initial report in early July. Industry officials have said that could mean a resumption of Proton flights in September, but even this remains uncertain. The current Proton manifest has commercial launches for mobile satellite services provider Inmarsat of London as the first customer, with Turksat of Turkey as the second and Eutelsat in third position. Whether any Russian government missions will be inserted between these commercial flights is not clear. Each month that passes is a month without EDRS revenue for Airbus. “It’s very unfortunate for us; no service means no pay,” said Evert Dudok, Airbus’s Communications, Intelligence and Security division, which manages EDRS. “This is what public-private partnerships are about — without a satellite up there, there is no payment and we think it’s likely the delay will last until the end of the year. We are hoping for the end of the year.” The second geostationary-orbiting satellite to carry an EDRS laser terminal is called EDRS-C. Avanti Communications of London is placing its own telecommunications payload on the satellite following an agreement with ESA and calls the satellite Hylas 3. Various delays have forced that satellite’s launch, originally set for 2015, into mid-2017. Addressing an EDRS panel here during the Paris Air Show, Dudok said the EDRS-C/Hylas 3 satellite remains on its revised schedule of a mid-2017 launch aboard a European Ariane 5 rocket. Airbus’s goal in the EDRS program is to create what it calls a global SpaceDataHighway, which for unbroken coverage would need at least one more geostationary satellite in orbit, over the Asia-Pacific. The company has been marketing SpaceDataHighway services to the U.S. government, selling the jamproof virtues of optical communications over radio frequencies, and the multi-gigabit-per-second throughput as higher-bandwidth alternative for unmanned aerial vehicles (UAVs). In presentations to prospective military customers, Airbus has said it ultimately plans four geostationary nodes. EDRS-A on Eutelsat 9B will operate from 9 degrees east. EDRS-C/Hylas-3 will operate from 31 degrees east. Airbus has said a hosted payload on telecommunications satellite for launch around 2020 could be placed at 130 degrees east, with a fourth node later positioned at 130 degrees west. To jump-start use of laser links by the U.S. military, Airbus entered into a partnership with General Atomics-Aeronautical Systems of Poway, California, the manufacturer of the Predator line of UAVs. Stefan Klein, head of General Atomics Specialtechnik Dresden GmbH, said General Atomics has designed its own airborne laser communications systems, for which a preliminary design review is expected this year. A first round of ground demonstrations should occur within two years, he said, with an airborne demonstration in 2018 or 2019. That could lead to production-line introduction starting at the end of the decade, he said. That schedule is at least two years behind what Airbus had planned.