This image from NASA's Dawn spacecraft shows Kupalo Crater, one of the youngest craters on Ceres. The crater has bright material exposed on its rim and walls, which could be salts. Its flat floor likely formed from impact melt and debris. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
This image from NASA’s Dawn spacecraft shows Kupalo Crater, one of the youngest craters on Ceres. The crater has bright material exposed on its rim and walls, which could be salts. Its flat floor likely formed from impact melt and debris. Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
NASA’s Dawn spacecraft has unveiled a new patch of intriguing bright features in the most recent series of striking close-up images taken just after the probe reached the lowest altitude it will ever reach during the mission.
From Dawn’s current altitude of 240 miles (385 kilometers) above Ceres, every image taken from now on of the “unique landforms” will be of the highest resolution attainable since the ship will never swoop down closer to the pockmarked surface for science. Continue reading “Dawn Unveils New Bright Features on Ceres in Striking Close-Ups”
An early 2015 Geminid from the morning of December 9th. Image credit and copyright: Kevin Palmer
Author’s note: as of Thursday morning December 10th, the Geminids are already active. Canadian Meteor Orbit Radar (CMOR) has picked up a consistent stream of radio pings hailing from the constellation Gemini over the last few mornings, and reports of early Geminid activity seen by observers worldwide have been reported. If you’ve got clear skies this weekend over the next few mornings, don’t miss a sure-fire shower.
A brilliant Geminid flashes below Sirius and Orion over Mount Balang in China. Credit: NASA/Alvin Wu
2015 looks like a fantastic year for the Geminids. With the Moon just 3 days past new and setting at the end of evening twilight, conditions couldn’t be more ideal. Provided the weather cooperates! But even there we get a break. With a maximum of 120 meteors per hour, the shower is expected to peak around 18:00 UT (1 p.m. EST, 10 a.m. PST) December 14th, making for two nights of approximately equal activity: Sunday night Dec. 13-14 and Monday night Dec. 14-15. Continue reading “Viewing Guide to the 2015 Geminid Meteor Shower”
An artist's image of Hayabusa leaving Earth. Hayabusa was a Japanese sample return mission to the asteroid 25143 Itokawa. The mission was a partial success. A sample mission to Earth's sister planet is the holy-grail for the exploration of Venus. Image credit: JAXA
A space-faring friend pays our fair planet a visit this week on the morning of December 3rd, as the Japanese Space Agency’s Hayabusa 2 spacecraft passes the Earth.
The Flyby
Rick Baldridge on the SeeSat-L message board notes that Hayabusa-2 will pass 9,520 kilometers from the Earth’s center or 3,142 kilometers/1,885 miles from the Earth’s surface at 10:08 UT/5:08 AM EST on Thursday, December 3rd, passing from north-to-south above latitude 18.7 north, longitude 189.8 east just southwest of the Hawaiian Islands.
Unfortunately, the sighting opportunities for Hayabusa-2 aren’t stellar: even at its closest, the 1.5 meter-sized spacecraft is about nine times more distant than the International Space Station and satellites in low Earth orbit. To compound the challenge, Hayabusa-2 passes into the Earth’s shadow from 9:58 UT to 10:19 UT.
The path of Hayabusa-2 past the Earth. Image credit: JAXA
Still, skilled observers with large telescopes and sophisticated tracking rigs based along the Pacific Rim of North America might just catch sight of Hayabusa-2 as it speeds by. The JPL Horizons ephemeris generator is a great resource to create a customized positional chart in right ascension and declination for spacecraft for your given location, including Hayabusa-2.
The Earth-Moon pair snapped by Hayabusa-2 on November 26th from about three million kilometers distant. Image credit: JAXA
Hayabusa-2 won’t crack 20 degrees elevation for observers along the U.S. West Coast, putting it down in the atmospheric murk of additional air mass low to the horizon. This also tends to knock the brightness of objects down a magnitude or so… estimates place Hayabusa-2 at around magnitude +13 shortly before entering the Earth’s shadow. That’s pretty faint, but still, there are some dedicated observers with amazing rigs out there, and it’s quite possible someone could nab it. Hawaii-based observers should have the best shot at it, though again, it’ll be in the Earth’s shadow at its very closest…
Amateur radio satellite trackers are also on the hunt for the carrier-wave signal of the inbound Hayabusa-2 mission. You can also virtually fly along with the spacecraft until December 5th: (H/T @ImAstroNix):
A simulation of tomorrow’s flyby. Image Credit: JAXA
Probably the best eye-candy images will come from the spacecraft itself: already, Hayabusa-2 has already snapped some great images of the Earth-Moon pair using its ONC-T optical navigation camera during its inbound leg.
A close-up of Hayabusa-2’s view of the Earth and Moon. Image credit: JAXA
Other notable missions used Earth flybys en route to their final destinations, including Cassini in 1999, and Juno in 2013. Cassini’s return caused a bit of a stir as it has a plutonium-powered RTG aboard, though Earth and its inhabitants were never in danger. A nuclear RTG actually reentered during the return of Apollo 13, with no release of radioactive material. Meant for the ALSEP science package on the surface of the Moon, it was deposited on the reentry of the Lunar Module over the Marinas Trench in the South Pacific. And no, Hayabusa-2 carries no radioactive material, and in any event, it’s missing the Earth by about a quarter of its girth.
The successor to the Hayabusa (‘Peregrine Falcon’ in Japanese) mission which carried out a historic asteroid sample return from 25143 Itokawa in 2010, Hayabusa-2 launched atop an H-IIA rocket from Tanegashima, Japan exactly a year ago tomorrow on a six year mission to asteroid 162173 Ryugu. This week’s Earth flyby will boost the spacecraft an additional 1.6 kilometers per second to an outbound velocity towards its target of 31.9 kilometers per second post-flyby.
Launch of an H-IIA rocket with Hayabusa-2. Image credit: JAXA
Like its predecessor, Hayabusa-2 is a sample return mission. Unlike the original Hayabusa, however, Hayabusa-2 is more ambitious, also carrying the MASCOT (Mobile Asteroid Surface Scout) lander and an explosive seven kilogram impactor. Hayabusa-2 will deploy a secondary camera in orbit to watch the detonation and will briefly touch down at the impact site to collect material.
If all goes as planned, Hayabusa-2 will return to Earth in late 2020.
NASA has its own future asteroid sample return mission planned, named OSIRIS-REx. This mission will launch in September of next year to rendezvous with asteroid 101955 Bennu in September 2019 and return to Earth in September 2023.
An artist’s conception on Hayabusa 2 at asteroid 162173 Ryugu. Image credit: JAXA
We’re entering the golden age of asteroid exploration, for sure. And this all comes about as the U.S. authorized asteroid mining just last week (or at least, as stated, ‘asteroid utilization’) under the controversial U.S. Commercial Space Launch Competitiveness Act. But the original Hayabusa mission brought back mere micro-meter-sized dust grains, highlighting just how difficult asteroid mining is using present technology…
Perhaps, for now, its more cost effective to simply wait for the asteroids to come to us as meteorites and just scoop ’em up. We’ll be keeping an eye out over the next few days for images of Hayabusa-2 as it speeds by, and more postcards of the Earth-Moon system from the spacecraft as it heads towards its 2018 rendezvous with destiny.
A new study indicates that in about a million years, a star will pass close to our Solar System, sending comets towards Earth and the other planets. Credit: NASA/JPL-Caltech
The story of KIC 8462852 appears far from over. You’ll recall NASA’s Kepler mission had monitored the star for four years, observing two unusual incidents, in 2011 and 2013, when its light dimmed in dramatic, never-before-seen ways. Models to explain its erratic behavior were so lacking that some considered the possibility that alien megastructures built to capture sunlight around the host star (think Dyson Spheres) might be the cause.
But a search using the SETI Institute’s Allen Telescope Array for two weeks in October detected no significant radio signals or other signs of intelligent life emanating from the star’s vicinity. Something had passed in front of the star and blocked its light, but what?
The Spitzer Space Telescope observatory trails behind Earth as it orbits the Sun. Credit: NASA/JPL-Caltech
Shattered comets and asteroids were also suggested as possible explanations — dust and ground-up rock would be at the right temperature to glow in the infrared — but Kepler could only observe in visible light where any debris would be invisible or swamped by the light of the star. So researchers looked through older observations made in 2010 by the Wide Field Infrared Survey Explorer (WISE) space telescope. Unfortunately, WISE observed the star before the strange variations were seen and therefore before any putative dust-busting collisions.
Not to be stymied, astronomers next checked out the data from NASA’s Spitzer Space Telescope, which like WISE, is optimized for infrared light. Spitzer just happened to observe KIC 8462852 much more recently in 2015.
“Spitzer has observed all of the hundreds of thousands of stars where Kepler hunted for planets, in the hope of finding infrared emission from circumstellar dust,” said Michael Werner, the Spitzer project scientist and the lead investigator of that particular Spitzer/Kepler observing program.
Comet Siding Spring (C/2007 Q3) imaged in the infrared by the WISE space telescope in January 2010. Credit: NASA/JPL-Caltech/UCLA
I’d love to report that Spitzer tracked down glowing dust but no, it also came up empty-handed. This makes the idea of an asteroidal smash-up very unlikely, but not one involving comets according to Massimo Marengo of Iowa State University (Ames) who led the new study. Marengo proposes that cold comets are responsible. Picture a family of comets traveling on a very long, eccentric orbit around the star with a very large comet at the head of the pack responsible for the big fading seen by Kepler in 2011. Later, in 2013, the rest of the comet family, a band of various-sized fragments lagging behind, would have passed in front of the star and again blocked its light. By 2015, the comets would have moved even farther away on their long orbital journey, leaving no detectable infrared excess.
“This is a very strange star,” said Marengo. “It reminds me of when we first discovered pulsars. They were emitting odd signals nobody had ever seen before, and the first one discovered was named LGM-1 after ‘Little Green Men.'”
Clearly, more long-term observations are needed. And frankly, I’m still puzzled why cold or less active comets might still not be detected by their glowing dust. But let’s assume for a moment the the comet idea is correct. If so, we should expect to see similar dips in KIC 8462852’s light as the comet swarm swings around again.
When WT1190F struck this atmosphere over the Indian Ocean around 6:20 Universal Time (12:20 a.m. CST) today , it broke apart into multiple fireballs against the blue sky. The object came down around 1:20 p.m. local time. Credit: IAC/UAE Space Agency/NASA/ESA
Clouds hampered observations from the ground in Sri Lanka during the re-entry of WT1190F overnight, but a team of astronomers captured spectacular images of the object from a high-flying plane over the Indian Ocean very close to the predicted time of arrival.
Peter Jenniskens of the SETI Institute and NASA Ames Research Center is shown here before the flight setting up the eleven staring cameras with a wider field of view, including two spectographic cameras, to catch the reentry. Credit: IAC/UAE Space Agency/NASA/ESA
The International Astronomical Center (IAC) and the United Arab Emirates Space Agency hosted a rapid response team to study the re-entry of what was almost certainly a rocket stage from an earlier Apollo moon shot or the more recent Chinese Chang’e 3 mission. In an airplane window high above the clouds, the crew, which included Peter Jenniskens, Mike Koop and Jim Albers of the SETI Institute along with German, UK and United Arab Emirates astronomers, took still images, video and gathered high-resolution spectra of the breakup.
Video and still imagery of WT1190F’s Reentry November 13, 2015
The group of seven astronomers hoped to study WT1190F’s re-entry as a test case for future asteroid entries as well as improve our understanding of space debris behavior. Photos and video show the object breaking up into multiple pieces in a swift but brief fireball. From the spectra, the team should be able to determine the object’s nature — whether natural or manmade.
Wide view of the colorful fireball and breakup when WT1190F struck Earth’s atmosphere. More than 20 cameras were used to record the event. Credit: IAC/UAE Space Agency/NASA/ESAAnimation from photos made on Nov. 12 when WT1190F was still in one piece in orbit about the Earth. Credit: Marco LangbroekFlying observatory. This Gulfstream 450 business jet, sponsored by United Arab Emirates and coordinated by Mohammad Shawkat Odeh from the International Astronomical Center, Abu Dhabi, was used by the team to observe and record the re-entry. Only five windows were available to make observations. Credit: IAC/UAE Space Agency/NASA/ESASETI Institute “staring cameras” used for wide field observations of the re-entry. Credit: IAC/UAE Space Agency/NASA/ESA
a short animation (spanning about 10 minutes) made out of my follow-up images. The first frame was obtained at 08:17UT while the second frame was obtained at 08:27UT of Nov, 12, 2015. (WT1190F is the star-like object at the centre while stars are trailed because the images were stacked on WT1190F motion). Credit: Ernesto Guido
No one’s 100% certain what WT1190F is — asteroid or rocket stage — but we are certain it will light up like a Roman candle when it re-enters Earth’s atmosphere around 6:20 Universal Time (12:20 a.m. CST) tomorrow morning Nov. 13.
Animation by Jost Jahn of WT1190F’s final hours as it races across the sky coming down off the coast of Sri Lanka
As described in an earlier story at Universe Today, an object discovered by the Catalina Sky Survey on Oct 3rd and temporarily designated WT1190F is expected to burn up about 60 miles (100 km) off the southern coast of Sri Lanka overnight. The same team observed it twice in 2013. Based upon the evolution of its orbit, astronomers determined that the object is only about six feet (2-meters) across with a very low density, making it a good fit for a defunct rocket booster, possibly one used to launch either one of the Apollo spacecraft or the Chinese Chang’e 3 lander to the Moon.
Below a plot of the last three orbits of WT1190F. The small red circle is the Earth. For scale, the large green circle is the orbit of the Moon. Notice that its final orbit takes straight into Earth. Credit: Bill Gray / Project Pluto
Additional observations of WT1190F have been made in the past few days confirming its re-entry later tonight. Checking the latest predictions on Bill Gray of Project Pluto’s page, the object will likely be visible from Europe about an hour before “touchdown”. To say it will be moving quickly across the sky is an understatement. Try about 3 arc minutes per second or 3° a minute! Very tricky to find and track something moving that fast.
Three 90-second exposures showing WT1190F zipping across the Rosette Nebula taken on Nov. 11, 2015 at the Konkoly Observatory in Hungary. Credit: Krisztián Sárneczky
58 minutes later, in the minute of time from 6:18 to 6:19 UT, WT1190F will move one full hour of right ascension and plummet 34° in declination while brightening from magnitude +8 to +4.5. If you’d like to attempt to find and follow the object, head over to JPL’s Horizons site for the latest ephemerides and orbital elements. At the site, make sure that WT1190F is in the Target Body line. If not, click Change and search for WT1190F in the Target Body field at the bottom of the window.
WT1190F re-Entry Trajectory. The object is expected to break up and fall harmlessly into the ocean. Credit: Bill Gray, Project Pluto
You’ll find updates at Bill Gray’s site. According to the most recent positions, the object will pass almost exactly in front of the Sun shortly before plunging into the ocean. Sri Lanka’s capital, Colombo, is expected to get the best views.
Because the mystery object’s arrival has been fairly well publicized, I hope to update you with a full report and photos first thing tomorrow morning. Like many of you, I wish I could see the show.
WT1190F observed on 9 October 2015 with the University of Hawaii 2.2 meter telescope on Mauna Kea, Hawaii. [Credits: B. Bolin, R. Jedicke, M. Micheli]
Get ready for a man-made fireball. A object discovered by the Catalina Sky Survey on Oct 3rd temporarily designated WT1190F is predicted to impact the Earth about 60 miles (100 km) off the southern coast of Sri Lanka around 6:20 Universal Time (12:20 a.m CST) on November 13.
The object orbits Earth with a period of about three weeks. Because it was also observed twice in 2013 by the same survey team, astronomers have the data they need to model its orbit and trajectory, and as far anyone can tell, it’s likely man-made.
The first two stages of the Saturn V rockets used to send the seven Apollo missions to the Moon fell back to Earth, but the third stage (S-IVB), pictured here, propelled the spacecraft into a lunar trajectory. Could this be WT1190F? Credit: NASA
Solar radiation pressure, the physical “push” exerted by photons of sunlight, is proportional to a space object’s area-to-mass ratio. Small, lightweight objects get pushed around more easily than heavier, denser ones. Taking that factor into account in examining WT1190F’s motion over two years, the survey team has indirectly measured WT1190F’s density at about 10% that of water. This is too low to be a typical asteroid made of rock, but a good fit with a hollow shell, possibly the upper stage of a rocket.
Spectacular re-entry of the Jules Verne ATV-1 cargo ship over the Pacific Ocean on September 29, 2008. Still image from a TV camera operated by Jessie Carpenter and Bill Moede of NASA Ames Research Center. A similar spectacle is expected on November 13 south of Sri Lanka.
It’s also quite small, at most only about six feet or a couple of meters in diameter. Most or all of it is likely to burn up upon re-entry, creating a spectacular show for anyone near the scene. During the next week and a half, the European Space Agency’s NEO (Near-Earth Object) Coordination Centeris organizing observing campaigns to collect as much data as possible on the object, according to a posting on their website. The agency has two goals: to better understand satellite re-entries from high orbits and to use the opportunity to test our readiness for a possible future event involving a real asteroid. The latter happened once before when 2008 TC3(a real asteroid) was spotted on October 6, 2008 and predicted to strike Earth the very next day. Incredibly, it did and peppered the Sudan with meteorites that were later recovered.
Assuming WT1190F is artificial, its trans-lunar orbit (orbit that carries it beyond the Moon) hints at several possibilities. Third stages from the Saturn-V rockets that launched the Apollo missions to the Moon are still out there. It could also be a stage from one of the old Russian or more recent Chinese lunar missions. Even rockets used to give interplanetary probes a final push are game.
Near-Earth object J002E3 discovery images taken by Bill Yeung on September 3, 2002. The 16th magnitude object was tentatively identified as the Apollo 12 third stage rocket. Animation created by Bob Denny.
Case in point. What was thought initially to be a new asteroid discovered by amateur astronomer Bill Yeung on September 3, 2002 proved a much better fit with an Apollo 12 S-IVB (third) stage after University of Arizona astronomers found that spectra taken of the object strongly correlated with absorption features seen in a combination of man-made materials including white paint, black paint, and aluminum, all consistent with Saturn V rockets.
On April 14th 1970, the Apollo 13 Saturn IVB upper stage impacted the moon north of Mare Cognitum. The impact crater, which is roughly 30 meters in diameter, is clearly visible in this photo taken by the Lunar Reconnaissance Orbiter. Credit: NASA/Goddard/Arizona State University
Apollo 13’s booster was the first deliberately crashed into the Moon, where it blew out it a crisp, 98-foot-wide (30-meter) crater. Why do such a crazy thing? What better way to test the seismometers left by the Apollo 12 crew? All subsequent boosters ended their lives similarly in the name of seismography. Third stages from earlier missions — Apollos 8, 10 and 11 — entered orbit around the Sun, while Apollo 12, which is orbiting Earth, briefly masqueraded as asteroid J002E3.
The nominal impact point is located about 60 miles south of the island nation Sri Lanka. Given the object’s small size and mass, it will likely be completely incinerated during re-entry. Credit: Bill Gray at Project Pluto
Bill Gray at Project Pluto has a page up about the November 13 impact of WT1190F with more information. Satellite and asteroid watchers are hoping to track the object before and right up until it burns up in the atmosphere. Currently, it’s extremely faint and moving eastward in Orion. You can click HERE for an ephemeris giving its position at the JPL Horizons site. How exciting if we could see whatever’s coming down before its demise on Friday the 13th!
Map showing TB145's position for an observer in the north central U.S. at 15-minute intervals starting at 5:00 UT. Subtract 4 hours from UT for EDT, 5 hours for CDT, 6 for MDT and 7 for PDT. Stars are shown to magnitude +12 and north is up. Credit: Chris Marriott's SkyMap
This simulation by Tom Ruen shows the trajectory of 2015 TB145 across the sky, showing tracer spheres spaced at one hour intervals along its path.
Halloween fireballs, a Supermoon and now a near-Earth asteroid flyby. What a week! While 2015 TB145 won’t be visible in binoculars because of its relative faintness and glare from a nearby waning gibbous Moon, you should be able to see it in an 8-inch telescope or larger telescope without too much difficulty.
Determined amateurs might even catch it in instruments as small as 4.5 inches especially tomorrow morning when the fleeing space mountain will brighten to around magnitude +10.
For western hemisphere observers, TB145 begins the evening in Orion’s Shield not far below the Hyades Cluster looking like a magnitude +11.5 star crawling northeast through the star field. By dawn on Halloween, it will top out around magnitude +10.2 as it zips through Taurus and Auriga traveling around 3-5° per hour depending on the time you look. For most of the night, TB145 will move swiftly enough to notice its motion in real time, resembling an Earth-orbiting satellite. Closest approach occurs around 17:00 UT (noon CDT) when it pass along bottom of the Big Dipper Bowl at around 10° hour. Amazing!
Map showing the asteroid’s progress across the horns of Taurus from 9-10:45 UT (4 – 5:45 a.m.) October 31st. It passes about 1° northwest of the Crab Nebula around 10:30 UT. Credit: Chris Marriott’s SkyMap
My hope is that these maps will help you spot and follow this zippy, aircraft carrier-sized boulder. Three of the four maps cover most of the time between 5:00 and 11:45 UT, equivalent to midnight CDT tonight to 6:45 a.m. tomorrow morning. I used the very latest orbital elements and hand plotted the positions (a tedious exercise but worth it!) at 15-minute intervals. For convenience, when you print them out, I’d suggest using a straight edge to draw a line connecting the position dots.
As we discussed in the previous Universe Today story, parallax comes into play when viewing any nearby Solar System object. Three of the maps show the asteroid’s position from the North Central U.S. One depicts the view from the South Central U.S. from 11-11:45 UT. Parallax is minor early on from midnight to 2 or 3 a.m. but becomes more significant near closest approach. This is based on comparisons I made between latitudes 47°-32° North.
By this time, TB145 will be around magnitude +10.4 and easier to see than at the start our run. The map covers the time from 11-11:45 UT (6 – 6:45 a.m. CDT). Credit: Chris Marriott’s SkyMap
I apologize for the limited number of maps in this article but hope these and the do-it-yourself approach described in the earlier article will be enough to set you on TB145’s trail.
The view from the southern U.S. (about 32° latitude) from 11-11:45 UT. Compared to the northern U.S., the asteroid’s path lies about 5 arc minutes further to the north. Credit: Chris Marriott’s SkyMap
As always when trying to spot asteroids on the move, pick a time and camp out at that spot with your telescope five minutes before the expected arrival time. Take the time to casually memorize the star patterns, so when the interloper arrives, you’ll pick it out straightaway. Again, depending on your location both east-west and north-south of the paths charted, TB145 may arrive a couple minutes earlier or later, but once you spot it, hold on tight. You’ll be going on a most exciting ride!
Map showing TB145’s approximate path starting at 4 hours UT on Oct. 31 (11 p.m. CDT Oct. 30). This view faces east. Tick marks show its hourly position. This map provides context for the detailed maps above. Credit: Chris Marriott’s SkyMap
We’d love to hear from you whether or not you were successful seeing it. If the weather’s uncooperative or you don’t have a telescope, Gianluca Masi’s got your back. He’ll webcast the flyby live on his Virtual Telescope site starting at 7 p.m. CDT (0:00 UT) tonight Oct. 30-31.
Now let’s see the flyby of Earth from the asteroid’s point of view, also by Tom Ruen. Enjoy!
Robotic sampling arm and capture mechanism to collect a multi-ton boulder from an asteroid are under development at NASA Goddard and other agency centers for NASA’s unmanned Asteroid Redirect Vehicle and eventual docking in lunar orbit with Orion crew vehicle by the mid 2020s. Credit: Ken Kremer/kenkremer.com
NASA GODDARD SPACE FLIGHT CENTER, MD – Rigorous testing has begun on the advanced robotic arm and boulder extraction mechanisms that are key components of the unmanned probe at the heart of NASA’s Asteroid Redirect Robotic Mission (ARRM) now under development to pluck a multi-ton boulder off a near-Earth asteroid so that astronauts visiting later in an Orion crew capsule can harvest a large quantity of samples for high powered scientific analysis back on Earth. Universe Today inspected the robotic arm hardware utilizing “leveraged robotic technology” during an up close visit and exclusive interview with the engineering development team at NASA Goddard.
“The teams are making great progress on the capture mechanism that has been delivered to the robotics team at Goddard from Langley,” NASA Associate Administrator Robert Lightfoot told Universe Today.
“NASA is developing these common technologies for a suite of missions like satellite servicing and refueling in low Earth orbit as well as autonomously capturing an asteroid about 100 million miles away,” said Ben Reed, NASA Satellite Servicing Capabilities Office (SSCO) Deputy Project Manager, during an exclusive interview and hardware tour with Universe Today at NASA Goddard in Greenbelt, Maryland, regarding concepts and goals for the overall Asteroid Redirect Mission (ARM) initiative.
NASA is leveraging technology originally developed for satellite servicing such as with the Robotic Refueling Mission (RRM) currently on board the International Space Station(ISS) and repurposing them for the asteroid retrieval mission.
“Those are our two near term mission objectives that we are developing these technologies for,” Reed explained.
The unmanned Asteroid Redirect Robotic Mission (ARRM) to grab a boulder is the essential first step towards carrying out the follow on sample retrieval with the manned Orion Asteroid Redirect Mission (ARM) by the mid-2020s.
ARRM will use a pair of highly capable robotic arms to autonomously grapple a multi-ton (> 20 ton) boulder off the surface of a large near-Earth asteroid and transport it to a stable, astronaut accessible orbit around the Moon in cislunar space.
“Things are moving well. The teams have made really tremendous progress on the robotic arm and capture mechanism,” Bill Gerstenmaier, NASA Associate Administrator for Human Exploration and Operations, told Universe Today.
Then an Orion crew capsule can fly to it and the astronauts will collect a large quantity of rock samples and gather additional scientific measurements.
“We are working on a system to rendezvous, capture and service different [target] clients using the same technologies. That is what we are working on in a nut shell,” Reed said.
This engineering design unit of the robotic servicing arm is under development to autonomously extract a boulder off an asteroid for NASA’s asteroid retrieval mission and is being tested at NASA Goddard. It has seven degrees of freedom and mimics a human arm. Credit: Ken Kremer/kenkremer.com
“Right now the plan is to launch ARRM by about December 2020,” Reed told me. But a huge amount of preparatory work across the US is required to turn NASA’s plan into reality.
Key mission enabling technologies are being tested right now with a new full scale engineering model of the ‘Robotic Servicing Arm’ and a full scale mockup of the boulder snatching ARRM Capture Module at NASA Goddard, in a new facility known as “The Cauldron.”
Capture Module comprising two robotic servicing arms and three boulder grappling contact and restraint system legs for NASA’s Asteroid Redirect Robotic Mission (ARRM). Credit: NASAThe ARRM capture module is comprised of two shorter robotic arms (separated by 180 degrees) and three lengthy contact and restraint system capture legs (separated by 120 degrees) attached to a cradle with associated avionics, computers and electronics and the rest of the spacecraft and solar electric power arrays.
“The robotic arm we have here now is an engineering development unit. The 2.2 meter-long arms can be used for assembling large telescopes, repairing a failed satellite, removing orbital debris and capturing an asteroid,” said Reed.
“There are two little arms and three big capture legs.”
“So, we are leveraging one technology development program into multiple NASA objectives.”
“We are working on common technologies that can service a legacy orbiting satellite, not designed to be serviced, and use those same technologies with some tweaking that we can go out with 100 million miles and capture an asteroid and bring it back to the vicinity of the Moon.”
“Currently the [capture module] system can handle a boulder that’s up to about 3 x 4 x 5 meters in diameter.”
Artists concept of NASA’s Asteroid Redirect Robotic Mission capturing an asteroid boulder before redirecting it to a astronaut-accessible orbit around Earth’s moon. Credits: NASA
The Cauldron is a brand new Goddard facility for testing technologies and operations for multiple exploration and science missions, including satellite servicing and ARRM that just opened in June 2015 for the centers Satellite Servicing Capabilities Office.
Overall project lead for ARRM is the Jet Propulsion Laboratory (JPL) with numerous contributions from other NASA centers and industrial partners.
“This is an immersive development lab where we bring systems together and can do lifetime testing to simulate what’s in space. This is our robotic equivalent to the astronauts NBL, or neutral buoyancy lab,” Reed elaborated.
“So with this same robotic arm that can cut wires and thermal blankets and refuel an Earth sensing satellite, we can now have that same arm go out on a different mission and be able to travel out and pick up a multi-ton boulder and bring it back for astronauts to harvest samples from.”
“So that’s quite a technical feat!”
The Robotic Servicing Arm is a multi-jointed powerhouse designed to function like a “human arm” as much as possible. It builds on extensive prior research and development investment efforts conducted for NASA’s current Red Planetrovers and a flight-qualified robotic arm developed for the Defense Advanced Research Projects Agency (DARPA).
“The arm is capable of seven-degrees-of-freedom to mimic the full functionally of a human arm. It has heritage from the arm on Mars right now on Curiosity as well as ground based programs from DARPA,” Reed told me.
“It has three degrees of freedom at our shoulder, two at our elbow and two more at the wrist. So I can hold the hand still and move the elbow.”
The arm will also be equipped with a variety of interchangeable “hands” that are basically tools to carry out different tasks with the asteroid such as grappling, drilling, sample gathering, imaging and spectrometric analysis, etc.
View of the robotic arm above and gripper tool below that initially grabs the asteroid boulder before the capture legs wrap around as planned for NASA’s upcoming unmanned ARRM Asteroid Redirect Robotic Mission that will later dock with an Orion crew vehicle. Credit: Ken Kremer/kenkremer.com
The ARRM spacecraft will carefully study, characterize and photograph the asteroid in great detail for about a month before attempting the boulder capture.
Why does the arm need all this human-like capability?
“When we arrive at an asteroid that’s 100 million miles away, we are not going to know the fine local geometry until we arrive,” Reed explained to Universe Today.
“Therefore we need a flexible enough arm that can accommodate local geometries at the multi-foot scale. And then a gripper tool that can handle those geometry facets at a much smaller scale.”
“Therefore we chose seven-degrees-of-freedom to mimic humans very much by design. We also need seven-degrees-of-freedom to conduct collision avoidance maneuvers. You can’t do that with a six-degree-of-freedom arm. It has to be seven to be a general purpose arm.”
How will the ARRM capture module work to snatch the boulder off the asteroid?
“So the idea is you come to the mother asteroid and touch down and make contact on the surface. Then you hold that position and the two arms reach out and grab the boulder.”
“Once its grabbed the boulder, then the legs straighten and pull the boulder off the surface.”
“Then the arms nestle the asteroid onto a cradle. And the legs then change from a contact system to become a restraint system. So the legs wrap around the boulder to restrain it for the 100 million mile journey back home.
“After that the little arms can let go – because the legs have wrapped around and are holding the asteroid.”
“So now the arm can also let go of the gripper system and pick up a different tool to do other things. For example they can collect a sample with another tool. And maybe assist an astronaut after the crew arrives.”
“During the 100 million mile journey back to lunar orbit they can be also be preparing the surface and cutting into it for later sample collection by the astronauts.”
Be sure to watch this video animation:
Since the actual asteroid encounter will occur very far away, the boulder grappling will have to be done fully autonomously since there will be no possibility for real time communications.
“The return time for communications is like about 30 minutes. So ‘human in the loop’ control is out of the question.
“Once we get into hover position over the landing site we hit the GO button. Then it will be very much like at Mars and the seven minutes of terror. It will take awhile to find out if it worked.”
Therefore the team at Goddard has already spent years of effort and practice sessions just to get ready for working with the early engineering version of the arm to maximize the probability of a successful capture.
“In this facility we put systems together to try and practice and rehearse and simulate as much of the mission as is realistically possible.”
“It took a lot of effort to get to this point, in the neighborhood of four years to get the simulation to behave correctly in real time with contact dynamics and the robotic systems. So the arm has to touch the boulder with force torque sensors and feed that into a computer to measure that and move the actuators to respond accordingly.”
“So the capture of the boulder is autonomous. The rest is teleoperated from the ground, but not the capture itself.”
How realistic are the rehearsals?
“We are practicing here by reaching out with the arm to grasp the client target using autonomous capture [procedures]. In space the client [target] is floating and maybe tumbling. So when we reach out with the arm to practice autonomous capture we make the client tumble and move – with the inertial properties of the target we are practicing on.”
“Now for known objects like satellites we know the mass precisely. And we can program all that inertial property data in very accurately to give us much more realistic simulations.”
“We learned from all our astronaut servicing experiences in orbit is that the more we know for the simulations, the easier and better the results are for the astronauts during an actual mission because you simulated all the properties.”
“But with this robotic mission to an asteroid there is no backup like astronauts. So we want to practice here at Goddard and simulate the space environment.”
ARRM will launch by the end of 2020 on either an SLS, Delta IV Heavy or a Falcon Heavy. NASA has not yet chosen the launch vehicle.
Several candidate asteroids have already been discovered and NASA has an extensive ongoing program to find more.
Orion crew capsule docks to NASA’s asteroid redirect vehicle grappling captured asteroid boulder orbiting the Moon. Credit: NASA
Again, this robotic technology was selected for development for ARRM because it has a lot in common with other objectives like fixing communications satellites, refueling satellites and building large telescopes in the future.
NASA is also developing other critical enabling technologies for the entire ARM project like solar electric propulsion that will be the subject of another article.
Therefore NASA is leveraging one technology development program into multiple spaceflight objectives that will greatly assist its plans to send ‘Humans to Mars’ in the 2030s with the Orion crew module launched by the monster Space Launch System (SLS) rocket.
The maiden uncrewed launch of the Orion/SLS stack is slated for November 2018.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
At NASA Goddard robotics lab Ben Reed/NASA Satellite Servicing Capabilities Office (SSCO) Deputy Project Manager and Ken Kremer/Universe Today discuss the robotic servicing arm and asteroid boulder capture mechanism being tested for NASA’s upcoming unmanned ARRM Asteroid Redirect Robotic Mission that will dock with an Orion crew vehicle in lunar orbit by the mid 2020s for sample return collection. Credit: Ken Kremer/kenkremer.com
