The Upper Atmosphere Research Satellite (UARS) reentered overnight Eastern Daylight Time (EDT) somewhere over the Pacific Ocean, but NASA is not yet certain precisely when or where.

At 3:47 am, NASA posted the following statement on its UARS website:

“NASA’s decommissioned Upper Atmosphere Research Satellite fell back to Earth between 11:23 p.m. EDT Friday, Sept. 23 and 1:09 a.m. EDT Sept. 24. The Joint Space Operations Center at Vandenberg Air Force Base in California said the satellite penetrated the atmosphere over the Pacific Ocean. The precise re-entry time and location are not yet known with certainty.”

Editor’s Note: The Twitter-sphere was active with many people following the blow-by-blow action, or lack thereof, as events unfolded through the wee hours EDT. Congrats to those who stayed up till the 3:47 announcement; this reporter called it a “day” at 2:30 am. NASA has done a poor job of keeping the public informed IMHO.

NASA does not know — and may never know — exactly where debris from the Upper Atmosphere Research Satellite (UARS) landed.

That was the message from NASA’s orbital debris expert, Nicholas Johnson, during a media teleconference this afternoon.

NASA has posted a map of the ground track for UARS’s final orbit. The vast majority of its final journey was over the ocean. NASA and Department of Defense specialists at the Joint Space Operations Center (JSPoC) estimate that the satellite reentered at 04:16 GMT (12:16 am EDT), although that is not known for certain. If that is correct, UARS would have been in the part of the ground track off the west coast of North America going up and over parts of Canada. Johnson said that if the satellite had survived that part of the trip, observers in the U.S. Pacific Northwest and Canada would have seen it, and there were no sightings. The nominal reentry point is shown on the map as a circle with a dot in the middle over the Pacific Ocean.

Essentially, if there was no one to see it, and it was out of range of the sensors that were tracking it, there is no way to know where the pieces fell. Johnson said that NASA is open to hearing from people — perhaps passengers on airlines flying over the Pacific at that time — who may have seen something, but otherwise, it will remain a mystery.

Johnson stressed that satellite or orbital debris reentries occur every day, and there are significantly sized pieces that come down each week. Something the size of UARS comes down about once a year. Unless there is some reason to do so, analysts do not bother to go back and try to determine the exact reentry times or places. In fact, he said, the usual procedure is for the North American Aerospace Defense Command (NORAD) to look for the object on three passes and if it is not located, they assume that it reentered.

NASA has not received any reports of injuries or debris being found. Johnson said that NASA routinely is contacted by individuals who believe they have found a piece of space debris and NASA checks out every one. Few actually are reentered space objects, he added, but if someone believes they have found a piece of UARS debris, they are welcome to contact the space agency (though NASA warns that the object should not be touched since it may be sharp). When asked if NASA wants the pieces returned, Johnson said that under existing agreements the pieces must be returned to NASA if requested, but NASA must pay the transportation costs and often does not request their return.

Twelve countries work together through the Inter-Agency Space Debris Coordinating Committee (IADC) to track and monitor reentries of space objects. Ten of the 12 participated in tracking the UARS reentry, Johnson said. Each has its own method of calculating expected reentry times, and over a decade of working together, they have found that one way is not clearly bettter than the others. All of the participants calculated about the same reentry time of 04:16 GMT, giving more credence to that as the most likely time.

An audiocast of the media briefing is available for one week by calling toll free in the United States: 866-516-0666.

UPDATE 3: At about 1:55 am NASA tweeted: “We’re still waiting for #UARS Done! confirmation. If debris fell on land (and that’s still a BIG if), Canada is most likely area.” Presumably that means they are confirming it has reentered, but don’t know where (not sure what the “we’re still waiting” phrase means).

UPDATE 2: 1:00 AM EDT Sept 24 — The status of UARS is unclear. NASA did not update its website between 10:30 pm and 12:55 am, and the 12:55 am update still reported orbital elements as of 10:30 pm. NASA tweeted about 12:40 am saying that it was possible that UARS has reentered, but they were awaiting confirmation from Strategic Command and that notation was finally added to the website at 12:55 am. Lots of rumors on Twitter, but no “news.” We will report here when an official announcement has been made.

UPDATE: 11:00 PM EDT Sept. 23 — NASA’s latest update predicts UARS will reenter between 11:45 pm tonight and 12:45 am Saturday morning EDT. The satellite will be passing over Canada, Africa, and vast ocean regions, it says, and the risk to public safety is “very remote.” Get updates on Twitter @SpcPlcyOnline

NASA’s 7:00 pm EDT update says that the risk to public safety from the reentry of its Upper Atmosphere Research Satellite (UARS) is “remote.”

The agency predicts that it will reenter between 11:00 pm tonight and 3:00 am Saturday morning EDT. The satellite will be passing over Canada, Africa and Australia during that time period, as well as “vast areas of the Pacific, Atlantic and Indian oceans.” The Earth is 70 percent covered by water.

The House Science, Space and Technology Committee heard from Apollo astronauts Neil Armstrong and Gene Cernan, former NASA Administrator Mike Griffin, and GRAIL principal investigator Maria Zuber today about the future of the U.S. human spaceflight program.

Committee chairman Rep. Ralph Hall (R-TX) emphasized that “America needs leadership with a compelling vision, and the strength of commitment” or young engineers will look elsewhere for their careers.

Rep. Eddie Bernice Johnson (D-TX), ranking Democrat on the committee, stressed that the space program is not only about building space hardware, but “about inspiring people” and “providing a peaceful and positive demonstration to nations around the world of American technological preeminence.”

Video of the hearing and the prepared statements of the witnesses are available on the committee’s website.

NASA has pushed back by a few hours the time when its Upper Atmosphere Research Satellite (UARS) is expected to reenter, which changes the locations where the debris may fall.

Yesterday, NASA forecast that the satellite would reenter this afternoon or early evening. Its track would not take it over North America at that time so the United States was not at risk.

Since then, the satellite changed its orientation or configuration, slowing the decay rate slightly and pushing reentry later into the evening or early Saturday according to NASA’s latest update, posted as of 10:30 am EDT today. NASA now reports that it cannot rule out the possibility that debris might land in the United States:

“Solar activity is no longer the major factor in the satellite’s rate of descent. The satellite’s orientation or configuration apparently has changed, and that is now slowing its descent. There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent. It is still too early to predict the time and location of re-entry with any certainty, but predictions will become more refined in the next 12 to 18 hours.”

The chances of any debris causing “a” human casulaty anywhere on Earth is one in 3,200 according to NASA, but calculations by The Weather Channel clarify that the chances that any particular individual — you –will be hit is more like one in 20 million. The Earth is 70 percent covered by water, so there is a good chance it will not hit land at all.

UPDATE: The Senate has tabled (killed) the House-passed resolution. Next steps are unclear.

ORIGINAL STORY: The House passed a new version of a Continuing Resolution (CR) to keep the government operating after October 1 late on Thursday, but it added another “offset” to the bill, which is likely to antagonize Senate Democrats.

The first version failed in the House when almost all Democrats and 48 Republicans voted against it. The Republican defections were viewed as an affront to House Speaker John Boehner (R-OH). Democrats opposed it because it provides about half the emergency funds ($3.5 billion) for disaster relief than the Senate already has approved ($6.9 billion), and because Republicans included a spending cut ($1.5 billion) to offset some of those costs. Traditionally, disaster relief funds are emergency spending that do not require immediate offsets.

Some House Republicans voted against it because the emergency funds were not completely offset — they wanted deeper spending cuts.

The House Republican leadership decided to try and get more Republican votes — they have the majority in the House — rather than trying to compromise with the Democrats. Hence, the new bill includes an additional offset of $100 million taken from a loan guarantee program to pay for a solar energy project that has gone bankrupt and become controversial (Solyndra). It worked. Enough Republicans changed their votes from nay to aye that it passed 219-203 on largely party lines according to Politico.

Democrats in the Senate had been able to win sufficient Republican support for their version of an emergency spending bill with no offset because of the large number of states with Republican Senators who have suffered from the year’s repeated natural disasters. Time will tell if they continue to support the higher level of emergency spending with no offset in light of the action by their House counterparts.

The House and Senate had planned to wrap up business today and head home for a week-long recess as some members observe Rosh Hashanah. Whether they will remain in session this weekend or return next week to work out their differences remains to be seen, but FY2012 begins a week from Saturday (October 1). None of the 12 appropriations bills that fund the government has been enacted, so the government will close down if a CR does not clear Congress by then.

UPDATE (FRIDAY MORNING): NASA reports the satellite’s decay rate slowed, pushing reentry later, and the United States may be at risk after all.

UPDATE (THURSDAY EVENING): NASA says reentry “is possible sometime during the afternoon or early evening of Sept. 23, Eastern Daylight Time.”

ORIGINAL STORY: NASA still isn’t sure exactly where debris from its Upper Atmosphere Research Satellite (UARS) will land, but it will not be on the United States.

The agency’s latest update is that UARS will reenter tomorrow (Friday) afternoon and its path will not take it over North America at that time. The reentry will be sometime tomorrow afternoon Eastern Daylight Time. The agency will continue to post updates as it refines the decay trajectory.

In a surprise result, the Continuing Resolution (CR) to fund the government after October 1 failed in the House.

Politico reports that the CR failed on a 195-230 vote as some Republicans joined “an overwhelming majority of Democrats.”

The CR, intended to keep the government operating after October 1, is controversial because it halves the amount of money voted by the Senate to deal with recent natural disasters and requires an “offset” — a reduction in federal spending to take account of the disaster relief efforts.

NASA’s update today on the reentry of the Upper Atmosphere Research Satellite (UARS) confirms that it will reenter on Friday, September 23. NASA no longer includes the plus or minus one day caveat — Friday is it.

The date is in United States time, but NASA stresses that does not mean it will reenter over the United States. “It is simply a time reference,” according to the agency’s UARS website.

Knowing the day it will reenter still does not provide a specific time and therefore specific location as to where the debris will fall. NASA will continue to update its website as the event nears.

Today’s update on NASA’s website about the impending reentry of the Upper Atmosphere Research Satellite (UARS) retains the prediction that it will come back to Earth on Friday, plus or minus a day. The prediction has been the same for the past several days.

Exactly when it will reenter remains uncertain. NASA says predictions will become more refined in the next two days. Where it reenters depends on when it reenters, so stay tuned.

The Weather Channel’s space weather twitter channel (@twcspacewx) tweeted some interesting statistics about the chances of a particular individual being hit by the debris. NASA’s assessment that there is a one in 3,200 chance of “a” human casualty does not mean that a particular individual — you — will be hit. TWC calculates that any single individual on Earth has about a one in 20 million chance. Check out their math on Twitter!