captioning sponsored by newshour productions, llc >> ifill: good evening. i'm gwen ifill. >> woodruff: and i'm judy woodruff. >> ifill: we bring you the newshour tonight, from the wells fargo center in philadelphia, site of this week's democratic national convention. >> woodruff: it's day three, and a star-studded night on the main stage, with speeches from president obama, vice president joe biden and hillary clinton's running mate, tim kaine. >> ifill: plus, part three of our hillary clinton biography series: the first lady steps out from the shadow of her husband, and into her own political identity. >> as soon as she had a job to do and was cabinet member of the united states, she seemed completely relaxed and completely focused on doing that job. >> sreenivasan: and i'm hari sreenivasan in washington. we'll have all the non- convention news of the day,

including the close of the high- profile freddie gray case. a controversial crime which sparked national protests, ends with charges dropped on three remaining officers involved-- a defeat for the city's top prosecutor. >> woodruff: all that and more, on tonight's pbs newshour. >> major funding for the pbs newshour has been provided by: ♪ love me true we can like many, but we can love only a precious few. because it is for those precious few that you have to be willing to do so very much. but you don't have to do it alone. lincoln financial helps you provide for and protect your financial future, because this is what you do for people you love. lincoln financial-- you're in

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station from viewers like you. thank you. >> woodruff: the democratic delegates have now completed their national ticket. this afternoon, they voice-voted the nomination of tim kaine as hillary clinton's running mate. later, president obama flies to philadelphia to make the case that his former secretary of state is the nation's best hope of coming together and keeping safe. correspondent john yang begins our coverage: >> reporter: at the white house, president obama prepped for this last convention as president. >> reporter: how do you feel about tonight, mr. president? >> what's happening tonight? oh... that was a joke. you look so serious. i feel great. >> reporter: also on the program, vice president biden, and hillary clinton's choice to be the next vice president. this morning, virgina senator tim kaine spoke to home-state

delegates. >> people are going to be able to see themselves in that office, who never could have imagined it before. i think it's great for men to be able to stand and support strong women leaders all across this nation. >> reporter: away from the convention, more fireworks over those hacked d.n.c. e-mails. american intelligence officials say it appears to be the work of the russian government. today, donald trump added fuel to the fire: >> i will tell you this-- russia, if you're listening, i hope you're able to find the 30,000 e-mails that are missing. i think you will probably be rewarded mightily by our press. let's see if that happens. >> reporter: the clinton campaign said that moves it from being a political issue to a question of national security. back in philadelhpia, bernie sanders urged supporters to close ranks behind the woman who

defeated him. >> it is not good enough just to elect hillary clinton. it is to transform america, and to make sure that we have a democratic senate, a democratic house and a democratic president who will do that. >> reporter: last night, dozens of sanders delegates walked out of the convention. >> we don't believe that clinton is a true democrat. we don't think she really believes in a true democracy. you count every vote, in every state, and you make sure they all have every right to vote, in every single way. she doesn't care about that. she has taken away our votes and our voice. we're making sure we're heard. >> reporter: in an interview with nbc news, mr. obama called for unity. >> one of the dangers in an election like this is that people don't take the challenge seriously. they stay home. and we end up getting the unexpected. >> reporter: a message he'll bring directly to the delegates tonight. for the pbs newshour, i'm john yang in philadelphia.

>> ifill: next, we head down to the convention floor, where npr's weekend edition sunday host rachel martin is standing by. rachel is joining us every night this week as part of our joint pbs newshour and npr convention coverage. rachel, what should we be expecting tonight? >> big win. so the last couple of night here at the democratic national convention have been about healing the wounds caused in the pry pair battle. tonight, democrats will try to turn the page. the focus will be on two important issues, national security and the economy. over the past couple of days, donald trump has really hammered the democrats saying where's the conversation about i.s.i.s.? where's the talk about the threat from terrorism? tonight will be the democrats' chance to answer that and they will do it with heavy hitters -- leon panetta, former director of the c.i.a. and former director of defense and will make the case for why hillary clinton should be the next

commander-in-chief. vice president joe biden said democrats have forgotten how to talk to white blue-collar voters and he will reach out to them. we'll hear from tim kaine, the vice presidential pick, and the keynote will be from barack obama, arguably hillary clinton's most powerful surrogate. all eyes will be on him and his message this evening. thank you. >> woodruff: thank you. conventions are often a place where relative newcomers capture the national political spotlight. in 2012, that was true for julian castro-- then-mayor of san antonio. he's now in president obama's cabinet as secretary of housing and urban development. his brother, joaquin castro, is a second-term congressman from san antonio. both are being floated as potential next heads of the democratic national committee, and both join us now.

we welcome you to the program. julian castro, first, i have to ask you, you were clearly on the list for hillary clinton, considered as her vice presidential running mate. you did a tryout. you campaigned with her. she chose tim kaine, was he the best choice? >> oh, i think he was. she chose an excellent man. he's very well prepared, being a improve, senator , sitting on the senate foreign relations committee. most importantly, he shares a broad, includive view of america, so he will be a great vice presidential nominee and a great vice president to serve her. >> ifill: let's talk about the great inclusive role, congressman castro, we know tim kaine among other great qualities speak spanish fluently. how do you think about how this campaign is playing out, whether texas is in play and whether latino voters are in play for donald trump?

>> i think the clinton campaign is going an excellent job connecting with latino voters. we've seen more permanent residents in this cycle wanting to become citizens, many hispanics registering to vote and that's a good thing. and i believe she will get upwards of 75% of the latino vote in this election. the fact is donald trump is trying to divide americans along racial and ethnic lines and it's unhealthy for the country. i say that as somebody who our grandmother came here from mexico when she was six years old and she was ant murderer or a rapist, she was an orphan who came with her sister. so to hear donald trump kick off his campaign with a slur against immigrants was hard to take. >> he truly has motivated the latino community more than any other presidential candidate i think in generations and motivated them in a negative way. so if the turnout rate in 2012 among hispanics was 48%, ill

expect it to go at least into the '50s for this election, and that's going to make a big difference in places like colorado, nevada, florida, even in places like virginia with northern virginia as diverse as it is. it was a mistake for the republicans to nominate someone who is seen in the hispanic community as being against them. >> woodruff: at the same time, congressman castro, you were quoted as saying just a couple of days ago that part of the vote that donald trump is attracting has to do with a fear about the economy. >> sure. >> woodruff: is hillary clinton addressing that? i know vice president jobes said in an interview i think just today that the party hasn't really spoken to those americans who are worried about the economy. >> no, i think that she is. president obama has brought this country back economically so far from where we were when he took office and hillary clinton will take that baton and take us even further. what she's doing is what we've done for generations which is

build out an infrastructure of opportunity in america, that means building great public schools, universities, a strong healthcare system, incliewppedding keeping the affordable care act and then an economy that works well with people so when they put in a hard day's work they can support seemselves and family members. that's what distinguishes us as a great nation. donald trump will tear it down. >> ifill: today donald trump suggested it may be okay if vladimir putin did some checking into hillary clinton's e-mails and shared them with the world. we've, of course, been dealing with the d.n.c. hack and there has been a lot of speculation among democrats that the russians are behind it. what's your reaction to that? >> it's troubling a foreign government would be trying to influence the outcome of a national election in the united states and secondly that you have a republican candidate who is embracing that effectively.

i especially cannot imagine anyone who grew up during the cold war era listening to donald trump and saying that's the guy i want to support. it makes zero sense and it's more evidence he's unfit, unprepared, just does not get it, should not be the commander-in-chief of this nation. >> woodruff: at the same time, again, congressman castro, it's clear not only are americans -- some of them -- concerned about the economy, they are worried about security. i.s.i.s. is out there, there have been a number of shootings this year for different parts of the country. you know, are we hearing from this democratic party at this convention what hillary clinton's plan is to do something? >> yeah, we absolutely will tonight and she has been talking about it on the campaign trail. she's imminently more qualified than donald trump on national security and foreign policy. you're right, terrorism has become a franchise in the middle east and north africa and increasingly other parts of the world and hillary clinton will

make sure americans are safe at home and abroad. >> ifill: let me help our viewers who are confused for a moment. this is joaquin castro, this is julian castro. >> even though we're twins, i'm a minute uglier than h he is. >> ifill: we were hoping you would wear your congressional pin and help us out. here's the thing, you have been on the scene long enough. a san antonio paper wrote you're double the talent and twice the ambition. so i'll give you the chance to be political analysts and tell us what does hillary clinton have to do in the next four months in order to win this thing? >> she has to do what she's been doing. she's going to have 30, 40 minutes tomorrow night to connect with the american people, not in a 30-second add, but to lay out her personal biography and why she's qualified and, you know, she's taken 25 years of attacks from the republican spin machine, and, so, she has the opportunity tomorrow to lay out the case, and i expect her to do that.

with tim kaine, she has somebody who can go out and carry that message well to diverse communities. they're going to be a very powerful ticket together and i expect that she's going to win in november. >> but jaquin castro -- here's my pin, by the way. >> woodruff: how come you didn't put that on earlier? >> i was going to do it later. >> woodruff: but, at the same time, hillary clinton, yes, she's out there making the case, but there's this big trust gap, if you will, that she has. how does she address that? >> well, i think she's just got to try to be herself and talk about issues americans care about which she's been doing. as julian said, this is somebody who faced an incredible head wind, not just on the national stage, but when she was first lady of arkansas and her husband was governor. so 28 years in the national spotlight and 40 years in politics. that's a lot of people running a lot of negative ads about you and trying to define who you are. tomorrow night, she gets to tell

the american people in an unvarnished way who she is, what she believes and what she sees for the country. >> ifill: julian castro -- joaquin castro -- i knew i was going to do this. joaquin castro, julian castro, good to have you. >> woodruff: i'm glad you did that and i didn't. thank you both. >> woodruff: and now we turn to the final installment of our three-part series on hillary clinton's life and legacy. tonight, a look at her post- first lady years, from her run for the u.s. senate, to her hard-fought race for the white house in 2008, and finally serving as america's top diplomat. we explore what drove hillary clinton to carve her own path in american politics. after supporting her husband's political aspirations for almost three decades, hillary clinton decided it was her turn. in february of 2000, while still in the white house, she threw her hat in the race to replace the longtime u.s. senator from new york, daniel patrick

moynihan. >> lots of people assume that hillary clinton has always had this driving desire to be president-- like, her entire life has been shaped by an ambition to be in the white house. and that may or may not be true, but what was certainly true was that it was not something that she could practically envision for herself, for a lot of her adulthood. her version of the story is that she did not consider taking on her own independent political career until the end of her husband's second term in the white house. >> woodruff: less than one year later-- with the soon-to-be- former president by her side-- clinton became the first first lady elected to public office. former white house aide david gergen calls clinton's senate years the finest, and probably most satisfying years of her public life. >> there's a famous phrase about when you go to the senate-- are you going to be a show horse or a workhorse? and she was very much the workhorse. >> woodruff: she served on the powerful senate armed services committee, worked to extend

healthcare to national guard members and fought for expanded services for veterans and their families. but one vote in particular would plague her for years to come. >> this is probably the hardest decision i've ever had to make. any vote that might lead to war should be hard. but i cast it with conviction. >> woodruff: clinton now calls her 2002 vote to authorize the use of military force in iraq a mistake. but in 2007, when she first set her sights on the presidency, she doubled down on the iraq decision. reporter indira lakshmanan calls it a political miscalculation. >> they thought it was a coronation. they thought that she was definitely going to have the democratic nomination in the bag. and so they were already, from the beginning, trying to have her run almost like a general election candidate. they were trying to have her be centrist or even right of

center, appeal to the so-called security moms. and they were still in this kind of post-9/11 mentality, without realizing that democrats were so disenchanted over the iraq war. >> woodruff: the 2008 campaign quickly ran into something else that caught them off guard-- a political newcomer named barack obama, who pulled off a surprise win in the iowa caucuses. clinton's loss there led to a memorable encounter with a voter, ahead of the new hampshire primary: >> my question is very personal. how do you do it? >> i couldn't do it if i didn't passionately believe it was the right thing to do. you know, i have so many opportunities from this country; i just don't want to see us fall backwards. >> it was at that moment that she showed her humanity and her vulnerability, and a lot of people credit that with turning the vote around for her in new hampshire.

>> woodruff: clinton went on to win new hampshire, along with 22 other states. however, it wasn't enough. deeply disappointed, she waited till after the last democratic primary in june to throw her support to obama. >> i move, senator barack obama of illinois to be moved by acclamation, as the nominee for president of the united states. >> woodruff: but then she campaigned hard for him, and soon after his november victory, she agreed to become his secretary of state. almost right away, clinton appeared more natural as the nation's chief diplomat, than she had been as a candidate: >> as soon as she had a job to do and was cabinet member of the united states, she seemed completely relaxed and completely focused on doing that job. >> woodruff: she worked to gain the respect of both foreign

allies and adversaries. >> even when there were times and places where people were not happy about u.s. foreign policy, were not thrilled to see her, she didn't back down and apologize for u.s. policies. it was interesting to see her, even in difficult situations, do a, sort of like, jujitsu. >> woodruff: but with many complex global challenges, it was also a time of disappointments and failures. >> she didn't get a middle east peace deal, she didn't get an iran nuclear agreement-- that was something that happened under her successor, john kerry. she didn't bring an end to the syrian war, and one wonders if that is a very high bar to hold her to, because some of those seem like they're intractable problems. >> woodruff: clinton was also a driving force in the white house's decision to militarily support the overthrow of libyan dictator muammar qaddafi. president obama now calls his

administration's lack of planning for what came next, the biggest mistake of his presidency. libya spiraled into chaos, and one year later the american consulate in benghazi, libya, was attacked; u.s. ambassador christopher stevens and three other americans were killed. republicans slammed clinton for not providing the outpost with sufficient security. >> what difference, at this point, does it make? >> we can all "monday morning quarterback"-look back at it now, and say, "was that a good decision, or was it not?" on the other hand, had tens of thousands of people been slaughtered in libya because the united states, france, libya and and britain and nato had not come in, you know the situation could've been worse. >> woodruff: clinton stepped down from the state department in february of 2013, amid speculation she was readying another run for the white house: >> i think what motivates her is to be a transformational woman

leader. i think she feels that she's been trained for this all her life, she's been preparing for it. you know, talented men have stepped forward and had that opportunity. time for a woman to be a leader. >> ifill: with that, we turn to syndicated columnist mark shields, "new york times" columnist david brooks, and amy walter of the cook political report, who are also joining us around this table each night for many long hours, for our live convention coverage. we saw bill clinton last night begin to make the case. today donald trump seemed to jump back into the spotlight. what's going on? >> he can't be out of the spotlight and clearly decided bad publicity is better than none. if you step back, what he did today was kind of amazing. it wasn't really treasonous but sort of felt that way, i mean, calling on the russians to release documents and presuming

they have them from hillary clinton's server. it's mind boggling, frankly, and if it was done in a normal career year, it would be a career ender but that's clearly not the case and he's stolen the spotlight and the democratic convention is the small screen and donald trump is the big screen. >> woodruff: do you agree, donald trump's stolen the spotlight, amy walter? >> well, you know, this convention tonight was already going to be focused on national security and there's been a lot of talk both in conservative media and we talked about it, too, with all the crises going on around the world and seems daily or weekly attacks in europe the fact that this convention has not yet brought that up has been glaring, and we now know we have leon panetta tonight, we're going to have the president talk about this, those issues were already going to be in the fore. but the question with donald trump, look, i completely agree with david. there is now an emoji going around that goes, does it

matter? what does this mean? and on the one hand that would be a career ender, the end of the campaign, where you're talking about temperament, et cetera, on the other hand you have a candidate in hillary clinton who has problems with e-mails and the issue of a server has been hacked is a big deal and havin having the focusn hillary clinton's vulnerable is not good either. >> ifill: we have the president of the united states, joe biden the vice president, tim kaine who was nominated this afternoon to be vice president, is it possible for anybody to steal that spotlight? >> i think donald trump absolutely dominated the story for the simple reason the republicans have enjoyed historically and recently an advantage over the democrats on national security, sort of national muscle issues.

it's about the concern of the security and the well being of people's lives. i think donald trump it frommed away -- fritted away. anytime e-mails and hacking are in the storks it is not good for the clintons. >> woodruff: with donald trump hanging out there and the other republicans sal investigate waiting for there to be a big mistake, a blowup out of this convention, what does hillary clinton need to do tonight and tomorrow night? >> i would say this is beginning to feel like a successful convention. the first couple of hours were rocky, a transition the first night, michelle obama's triumphant address, bill clinton's successful address and i imagine tim kaine will be very personal so it's feeling like a

successful conventional convention. but the thing we have to figure out is does that matter anymore? are the rules different? has the answer the for medication of society changed -- has the transformation of society changed the rules? we're witnessing a transformation of how society is done. >> and then add on top of that historic disapproval ratings for both these candidates. so what success normally would be is a bump coming out of this, and we've seen in recent years that the bumps have gotten smaller and smaller as the media landscape has changed. in this case for hillary clinton just to move her unfavorable ratings a couple of points would be success but she's still going to be underwater and i don't think most democratic strategists if they were honest would tell you they don't believe she's ever going to be in positive territory. is it a success on paper?

sure. but is it going to move the normal -- the numbers normally like we would see, unlikely. >> woodruff: well, mark, weigh in on this. >> the argument that always exists in campaigns, are we going to be a campaign of mobilization? are we going to up the numbers of our own base, voters, in this case, democrats will be minority voters, younger voters and women especially in hillary clinton's case to try and reconstruct the barack obama model and win on that, or do you go into persuasion which is to try and reach out and reach the disaffected republicans. i see no effort to make it legitimate for republicans to come over and to find what we have in common, especially republicans who are alienated, threatened and turned off by donald trump. i don't think michael bloomberg is the answer to that. that's not exactly your garden variety suburban republican. he left the republican party for his own devices and his own

interests. so i think the democrats, it ties hillary clinton very much to barack obama. david has talked about she has talked about change and how she's going to be different but at the same time it's an election of continuity. it has to be different but it has to be she's trying to get barack obama's constituency energized and out in this election. >> ifill: mark shields, i want to ask you a question. joe biden, tonight in many ways this is his farewell turn at least at a national convention. tell us about that. >> joe biden, it's what it might have been. i mean, 1988, elected to the senate 72 at the age of 29, 1988 a serious candidate, stumbled and feld on a plagiarism charge, bounced back, becomes president, was sought out as a possible likely candidate to succeed barack obama in spite of his age

and the personal tragedy of his son's death and him a grandfather. but joe is a throwback to the time when senators knew each other on the other side of the aisle, when they traveled across the world together, when they knew each other's children, when their kids went to school. it was a different washington, and joe biden embodies it at its best. >> woodruff: we'll talk about it later tonight and joe biden embodies that best. and starting at 8:00 p.m. eastern, david, mark and amy will be back for our special npr-pbs newshour coverage of the democratic presidential convention here in philadelphia. for now, back to hari in washington. >> ifill: but for now, back to hari in washington. >> sreenivasan: thank you both. in the day's other news: the man

who tried to assassinate president ronald reagan will go free as early as next week. a federal judge ruled today that john hinckley jr. no longer poses a risk. hinckley shot and wounded president reagan in march 1981. he was found not guilty by reason of insanity, and sent to a washington mental hospital. he's now 61, and already spends 17 days a month at his mother's home in virginia. in syria, the islamic state group has claimed a massive truck bombing that killed at least 48 people and wounded dozens today. the target was a crowded district in a kurdish-held city near the turkish border. thick smoke poured into the air in the aftermath of the blast, and the resulting fires set off additional explosions. christian and muslim leaders in france called for solidarity today, after islamic state attackers killed an elderly catholic priest. the leader of the main mosque in paris said all french muslims condemn such acts. meanwhile, mourners left flowers and lit candles at a makeshift memorial. and, pope francis weighed in, saying "the world is at war."

>> ( translated ): when i speak of war, i talk about real war. not a religious war, no. there is a war of interests, a war for money, a war for resources of nature and a war to control people. this is war. anyone who thinks i am talking of a religious war, no. all the religions want peace. >> sreenivasan: the pope spoke before arriving in krakow, poland for world youth day celebrations. hundreds of thousands of young people are expected to attend, under heavy security. the crackdown in turkey has claimed more victims-- 47 journalists were detained today. and, state media reports dozens of newspapers and tv stations were closed. the government says it is rooting out supporters of an opposition cleric, accused of fomenting this month's failed coup. back in this country, the federal reserve left interest rates unchanged again, but it also said near-risks to the economy have lessened. that leaves open the possibility of raising rates later this year. the news did little for wall street. the dow jones industrial average lost a point, to close at 18,472. the nasdaq rose 29 points, and

the s&p 500 slipped two. and officials in hiroshima, japan are the latest to object to the smartphone game sensation "pokemon go." they say players are descending on the atomic bomb memorial park, and asking that the site be removed from the game. they want it done before august 6th, the anniversary of the u.s. attack that destroyed much of the city. >> sreenivasan: in a surprise move today, prosecutors in baltimore dropped all remaining charges against three police officers in the freddie gray case. gray died of spinal cord injuries last year, after being arrested and transported unsecured in a police van. his death sparked widespread protests, looting and arson across baltimore. prosecutors charged six officers connected to the arrest, all of whom pleaded not guilty. the first trial resulted in a hung jury and mistrial. three others ended in separate

acquittals. baltimore state's attorney marilyn mosby called today's decision "agonizing." >> we stand by the medical examiners determination that freddie grey's death was a homicide. however, it has become clear to me that without being able to work with an independent investigator, without having a say in the election, in whether our cases proceed in front of a judge or a jury, without real substantive reforms to the current criminal justice-- we could try this case 100 times, and cases just like it, and we would still end up with the same result. >> sreenivasan: after she spoke, the head of the police union in baltimore called ms. mosby's comments "outrageous." lawyers for the police officers had argued that their client's actions during the gray arrest were justified. for more on all this we are again joined by debby hines.

she is a former baltimore prosecutor who today practices law in washington, d.c. first, were you surprised by the deits -- the decision this morning? >> i think everyone was, myself included. as it looked, officer miller's case was going to start to trial this week and then officer porter would have been tried later and sergeant alicia white. so i don't think anybody saw it come bug was a good move on the part of the state's attorney if she evaluated it and came to the determination there is no new evidence she can put forth in the cases. like she said, if she tried it a hundred times more before judge williams she would get the same result. so it was a good decision. >> sreenivasan: a way to cut her losses? >> we don't look at it that way. i mean, in terms of prosecution, it's not a baseball game or a football game in deciding what you will do to cut your losses. it's real-life criminal

prosecution. so i think what she decided is not cutting her losses but hopefully having her team and other members evaluate and just determining there wasn't any way they were going to get a conviction based on the evidence they have from the police officers. >> sreenivasan: is there anything else that can happen to the officers now? any sort of administrative discipline? >> that's a good question. yes, the officers will be reviewed administratively and that's a different, more informal -- more formingle process but not as high a as beyond a reasonable doubt in a criminal process. so now the officers can still face suspension or firing or any other type of sanction that the baltimore city department would determine and interestingly enough, it will not be the baltimore city police department that is going to make the decision because to have the high profileness of the case, it

has actually been assigned to howard county in maryland and i believe montgomery county, i believe one or both of those jurisdictions together are going to be looking at the evidence against the officers to see if there was any misconduct. >> sreenivasan: as you say, there are separate standards, so there is a possibility they could face administrative discipline but there wasn't enough evidence for a criminal conviction? >> exactly. and, you know, there have been officers who have been fired for misconduct in office and we know there weren't criminal charges brought in most cases, we're seeing how it shakes out with these officers. the criminal standard is the highest of standards beyond a reasonable doubt, and in an administrative situation, it's just whether they violated any of the orders that the police

department had. >> sreenivasan: what about the process of transporting people from a crime scene to jail? is that changing? has that changed. >> reporterchanged?it seems bala history of settling lawsuits for this very practice. >> exactly. it's been difficult to prove in a criminal court of law what is a rough ride, but there has been change already as a result of the freddie gray case. there will be videos put in the police vans so they will be operating and we can see exactly what happens inside the van. there was a general order that has already been presented by the baltimore city police chief toe all of his evtire force that, from this point forward, the detainees, prisoners, they must be seat-belted, they cannot be lying face down when the

floor of the van -- on the floor of the van, handcuffed and shackled. last thing, a definitely change is if a prisoner asks for a medic, the officers must at least get a medic, a paralegal or have the person sent to the hospital. >> sreenivasan: any impact on ms. mosby's career? >> she's a political public servant. she's elected. she just started in january of 2015 before these cases, and, so, it's too early to say what will happen with her career. i mean, she definitely has a very promising career, and i would hope that the citizens of baltimore would not judge her by the actions of what happened in these cases because just bringing the cases, hari, is going to bring about some change in baltimore city policing. >> sreenivasan: all right, debby hines, thank you so much for joining us today. >> thank you, hari.

>> sreenivasan: nasa is trying to fight fire with fire, in space. researchers are conducting new experiments that would limit fire danger for future space travel. science correspondent miles o'brien has our encore look at this story, part of our weekly series on the "leading edge" of science and technology. >> reporter: we are crossing an international boundary. we are on the u.s. side now, and now we are on the russian mir space station. >> reporter: by 1997, the russian space station mir was 11 years old and showing its age. during the fifth shuttle mission to the station, astronaut john grunsfeld documented the warren of modules brimming with a disorienting maze of cables, hoses and trash. >> i feel like i am exploring a cave. >> reporter: can you imagine being in a fire here? u.s. astronaut jerry linenger lived that nightmare on february

23, 1997. >> the fire was basically in this region here, with the flames shooting across. >> reporter: the source was a canister filled with chemicals designed to generate oxygen. >> it's got built in fuel. you've got a two or three foot flame, blowtorch-like in intensity, sparks flying off the end of it, it looks like a hundred sparklers all at once. >> reporter: linenger and his russian crewmates donned masks and frantically fought the fire. >> the fire took about 14 minutes total, and 14 minutes is a long time with a roaring fire and a blackout from the smoke, and no place to go. and if it were any bigger, i'm pretty darn sure we would have lost that spacecraft. >> reporter: for nasa scientists and engineers it was a big wake- up call. >> one of the things that you learn is, we really didn't have a way to put that fire out. >> reporter: gary ruff is a scientist at nasa's glenn research center in cleveland ohio. this is where the agency does most of its research on fires in the weightless environment of

space called microgravity. >> they used water foam fire extinguishers that they had, but that probably at most just kind of cooled everything else around it and kept it from spreading. >> reporter: ruff leads a team that is trying to learn more about big fires in space. so the plan is to deliberately set one, and watch what happens. really! >> this is the saffire iii module. >> reporter: david urban is the principal investigator for the spacecraft fire experiment or saffire. we spoke beside saffire iii, slated for launch at the end of 2016. the one currently in space, saffire i, is an identical box strapped inside a cargo ship. once the craft makes its delivery, departs and is a safe distance from the international space station, it will be time to light the fire inside saffire. fire and a spacecraft is a pretty scary thing, isn't it? >> yeah. it's a very small space. what you would normally tolerate

in your house, are completely nontolerable in a spacecraft. >> reporter: nasa's most painful fire lesson came in 1967, when three astronauts were killed during a countdown test on the launchpad in florida. it prompted a lot of changes in spacecraft designs. the agency took great pains to eliminate flammable materials wherever possible. but fires in microgravity are harder to predict. a lot of unanswered questions about fires in microgravity, right? >> a huge number. basically, we don't really know how fast they'll grow or how large they'll get, nor do we really understand, given the way the spacecraft are built, how quickly that temperature and pressure rise will be a problem for the crew. >> reporter: on the ground, when you light a candle, the heat of the flame melts the wax near the wick. this wax is drawn up the wick and vaporizes, fueling the flame. so if gravity is pulling everything down, why does a flame go upwards?

the air surrounding a flame puts pressure on it. but because gravity pulls colder, denser air down, there is more pressure exerted on the bottom of the flame. that's what pushes the flame up-- its buoyancy, the same thing that keeps a boat afloat. in space, when the gravity meter reads zero, the cool dense air no longer flows downward. instead, the air puts equal pressure on the flame from all directions. the end result-- candle flames in space are spherical. over the years, nasa has conducted several combustion experiments on small samples of paper, cloth, plastics and hydrocarbons in special chambers on skylab, the space shuttle and station. >> but they've all been really small. and so, one of the open questions that we've got is, how large that flame can get, how

but their main instrument will be two cameras and some controlled lighting. the images and the data will be beamed back to earth. when the experiment is done, the cargo ship will be guided to its own fiery end over the south pacific. the saffire team is planning three more experiments, for a total of six. the fires will be larger, eventually simulating a full-fledged spacecraft fire scenario. >> since we're going to release the gases into the cabin, we want to have some material there that the crew would have, to help clean up after a fire. >> reporter: jerry linenger certainly would not disagree with that. >> packing up, time to head home. >> reporter: linenger made it home safe and sound after all, but by the skin of his teeth. >> people say how brave you were-- i don't know. bravery, you've got to have an option.

you've got to have an option to run. >> reporter: as nasa sets its sights on long duration human missions to mars, it really isn't a question of "if" there will be a fire, just when-- and how will the crew be equipped to respond? miles o'brien, the pbs newshour, cleveland. >> sreenivasan: online right now, back to judy and gwen in philadelphia. >> ifill: here now for a lighter take on the conventions: samantha bee is host of "full frontal," a late night talk show that debuted on tbs in february. the comedian made her name as a correspondent on "the daily show" with jon stewart. >> i don't know what it means. i'm just doing the work and keeping my head down and my eyes forward, as i'm sure you do every day. >> ifill: most of it is politics, though, isn't it?

>> well, yes, but isn't all of life? >> ifill: you told rolling stone that having trump as the nominee of the republican party had been a god send for you. what did you mean? >> well, i mean, when you're trying to launch a s satirical show politically, what better gift than someone who turns out offensive ideas and statements on a daily basis, sometimes multiple times a day. we have been lucky. >> ifill: would you say you're a democrat, republican or knighter? >> definitely my leanings are very clear from the show but i prefer to think of myself in a more independent way. >> ifill: why? why not just embrace it? >> i do. i'm excited for hillary. i don't think there is any question about it. i like to be able to make jokes about both sides of the aisle. i like to give myself a little freedom. >> woodruff: what kind of

material was hillary clinton provide? if donald trump is the gift that keeps on giving wharkt about her? >> well, it is a little more challenges. definitely last week we found ourself with such an abundance of material from, monday to thursday it was incredible, an overflowing basket of goodies for us to choose from. in fact, we do a show that's three acts long and 21 minutes and we ended up writing six acts of comedy and doing all of the extras as webex trass and putting them up on the web. this week we're finding it, but, you know, we're having to find a sliver to get if. it's more nuanced. it's not just a banquet to select from. we have to dig a little deeper for sure. >> ifill: your show is tough. you use tough language. >> yes. >> ifill: we could not really air it here. >> ifill: i know. it's a salty show. >> ifill: we people are not used the hearing from a woman. >> no, they're not that used to

it. >> ifill: what kind of feedback do you get? >> i don't -- you know, i stay out of the feedback loop to be honest. i don't engage wit too much because i know i'm doing a show that comes from my heart. we're doing a show that comes from a place of passion and interest, and we use salty language because that's the language we feel like use together express our thoughts and concerns and it's really cathartic for us, and i tend to not drop into the criticism of that. i prefer to steer my own ship and not -- you know, i think anytime you try to create comedy or a piece of art by consensus, i mean, it's impossible to do a quality product, and i think -- so i don't listen to critics all that much. i don't read about myself. it's actually paradise, if i may. you can live in a bubble in which you think you're doing a good job all the time if you don't read what other people say. >> woodruff: samantha bee, you

expressed views on how few women are doing what you do, light-night comedy or any kind can of comedy, having their own show. why aren't there nor women doing that? >> i wish i had a great answer for that but the truth is i really don't know. i do think that will change and i certainly hope that it will change. i would love to have a sisterhood of late-night comedy hosts. >> woodruff: do you think it puts more pressure on you? >> well, as i said, i stay out of that feedback. so the pressure, i don't allow that pressure to really infiltrate. i with let that conversation be held by other people. >> ifill: diversity in news rooms is a big issue. what you see on the air is often reflective of the interests of the people who are deciding they're going to tell you what you need to know. in a comedy writer's room, do you have more women and people of clor than we normally see? >> i believe we do and we certainly made an absolute effort to -- we wanted to create a diverse workplace. that was one of our missions

from the very start. the show owner jill miller and myself are both women who we feel like we didn't fall into comedy writing if an obvious way. we didn't begin our lives thinking i'm going to be a comedy writer one day and host my own show. we both worked on the fringes, worked at other jobs and came to it rather late in life. so we identify with people who don't have access to comedy rooms and we wanted to definitely create a space in which we could bring people in from the outside, people who would not expect to naturally work in comedy, and we make efforts to do that, i mean, every day and in every way. >> we will keep looking for you here in philadelphia. >> thank you. >> ifill: samantha bee, "full frontal," thanks for dropping by. >> woodruff: thanks for making us laugh. >> we could all use a laugh.

>> woodruff: finally tonight, we mark the end of the primary season and look back at some of the iconic photographs from the 2016 campaign ths far, and we hear from the talented men and women who capture those images. covering politicians is fascinating because they're almost like another breed. as a political photojournalist, my job isn't only to document their message but it's also to document the human being. my name is molina mara, national political photographer for "the washington post" and i have been on the campaign trail with hillary clinton for about a year and a half. i think she's very comfortable with who she is as a person. i have a great time photographing her because she's full of expression and physical. >> i think just photographing trump is fascinating. he is such a character. h he's very conscious of the camera, he loves the camera and it comes across in his pictures. >> my name is chip and i have been a staff photographer for gedy images in washington, d.c. for 11 years.

this campaign cycle blended in immediately from the last, so we have been covering this campaign the last four years more or less. >> in my experience in over 30 years of doing this, there has never been a campaign cycle like this. >> my name is jim borg, editor and writer. in presidential campaign photography, you used to show up for the events, have a lot more interaction with the candidates, yourself personally, this campaign has been dramatically different in this regard. now the two nominees have staffs and campaigns that are much more aggressive about keeping the press at a distance than we've ever experienced before. >> all these events are orchestrated, andism like it's the photographer's job to try and circumvent that. my name is is mark peterson, and for this campaign cycle, i have been doing pictures for msnbc

photography. i started the political theater project in 2013. with this, you know, i converted the stuff to black and white and really accented the flash, and i use that to try and make things have more of a dimension to it and also to high light the theatrical nature of it. >> something i discovered early on is the crowds were more interesting than the candidates because the crowds spoke to who the candidate was. my name is hillary swift and i'm a freelance photographer for the "new york times." this has been the first campaign and convention i've ever worked on. it's been really surprising to me in a lot of ways in getting to see people from all over the country coming together and showing up to support someone, and often also showing up to not support ideas that they don't agree with. >> in 2016, we are needed.

a political photojournalist brings something that words can't do, brings the humanity to the coverage, and it really is who this person is, and it really does educate the voter in a way that they can say, who are you? can i vote for you? >> woodruff: i don't know what we would do without these photographers. they're amazing. >> ifill: still shots sometimes capture more than moving pictures. >> woodruff: for sure, even though we love tv. here in philadelphia, the "newshour" for now. but stay with us. we'll be back right here at 8:00 p.m. eastern for live special coverage of the democratic national convention, where vice presidential nominee tim kaine will speak, followed by president obama. i'm judy woodruff. >> ifill: and i'm gwen ifill. for all of us at the pbs newshour, thank you and we'll see you back here soon. >> major funding for the pbs newshour has been provided by:

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